Trianionic NCN³⁻ pincer complex of chromium and tetraanionic OCO⁴⁻ pincer complex of tungsten

MISSING IMAGE

Material Information

Title:
Trianionic NCN³⁻ pincer complex of chromium and tetraanionic OCO⁴⁻ pincer complex of tungsten pre-catalysts/catalysts for alkene and alkyne polymerization
Physical Description:
1 online resource (307 p.)
Language:
english
Creator:
McGowan, Kevin Patrick
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Chemistry
Committee Chair:
Veige, Adam S
Committee Members:
Aponick, Aaron
Murray, Leslie Justin
Christou, George
Hagelin, Helena Ae

Subjects

Subjects / Keywords:
acetylene -- catalyst -- chromium -- ethylene -- phenylacetylene -- pincer -- polymerization -- tetraanionic -- trianionic -- tungsten
Chemistry -- Dissertations, Academic -- UF
Genre:
Chemistry thesis, Ph.D.
Electronic Thesis or Dissertation
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )

Notes

Abstract:
This dissertation details the synthesis of 1) a trianionic NCN pincer-supported CrIV-methyl complex and its application as an alkene polymerization pre-catalyst and 2) two tetraanionic OCO pincer-supported WVI metallocyclopropene complexes and their application as an alkyn polymerization catalysts. The synthesis of the NCN CrIV-methyl complex2,6-iPrNCNCrIVMe(THF)(6) occurs by treating CrMeCl2(THF)2 with the dilithio salt pincer ligand precursor {2,6-iPrNCHNLi2}2 (3). The main product of the reaction are CrIII 2,6-iPrNCNCrIII(THF)3 (5), CrIV-Me complex (6) and CrII 2,6-iPrNHCNCrII(THF)2 complexes (7). Complex 6 is a rare example of a CrIV-methyl complex that is stable at 25 ºC. However, at 85 ºC,the Cr-Me bond undergoes homolysis. The metal-containing product from the thermolysis is the same CrII (7)formed during the metallation, except the proton on one nitrogen is substituted for a deuterium atom (7-d). The CrII species actively catalyses the selective isomerization of 1-alkenes to 2-alkenes. The NCN CrIV-methyl complex 2,6-iPrNCNCrIVMe(THF) (6), upon activation by triisobutylaluminum (TIBA), catalyzes the polymerization of ethylene. 1 µmol of complex 6 polymerizes ethylene with an activity of 7.02 x 106 g PE(molCr)-1 h-1 (75ºC). Based on the large polydispersities of the polyethylene, multiple active sites are operable and complex 6 most likely only acts as a pre-catalyst. Two tetraanionic OCO pincer-supported WVI metallocyclopropene complexes form upon treating tBuOCOW=C(tBu)(THF)2 (15) with 2 equiv. of phenylacetylene in toluene-d8 at -35 ºC. These two products areO2C(tBuC=)W(n2-HC=CPh) (16-tBu)and {O2C(PhC=)W(n2-HC=CtBu) (16-Ph){where OC(tBuC=)O = 2,6-(tBuC6H3O)2C6H3(tBuC=)4-,  OC(PhC=)O = 2,6-(tBuC6H3O)2C6H3(PhC=)4. Complexes 16-tBu and 16-Ph are the active catalysts for the polymerization of acetylenes. They polymerize a wide variety of acetylenes. With a substrate to catalyst loading ratio of 25,000 to 1,complex 16-tBu polymerizes phenylacetylene and 1-decyne with catalytic activities up to 5.64 x 106 gPPA mol-1h-1 and 7.98 x106 gPA mol-1 h-1,respectively. Treating 16-tBu with 10 equiv. of MeC=CPh in toluene-d8 at 75 ºC selectively incorporates one additional acetylene unity. The MeC=CPh inserts into the metallocyclopropene to form a metallocyclopentadiene ring. The insertion yields two isomers, OC(tBuC=)OWk2-C(Ph)=C(Me)C(H)=C(Ph) (18A) and OC(tBuC=)OWk2-C(Me)=C(Ph)C(H)=C(Ph)(18B). Complexes 18A and 18B provide reasonable evidence for an insertion/ring expansionpolymerization mechanism for chain propagation.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (Ph.D.)--University of Florida, 2013.
Local:
Adviser: Veige, Adam S.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-11-30
Statement of Responsibility:
by Kevin Patrick McGowan.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2013
System ID:
UFE0045326:00001


This item is only available as the following downloads:


Full Text

PAGE 1

1 TRIANIONIC NCN 3 PINCER COMPLEX OF CHROMIUM AND TETRA A NIONIC OCO 4 PINCER COMPLEX OF TUNGSTEN: PRE CATAL YSTS/CATALYSTS FOR ALKENE AND ALKYNE POLYMERIZATIO N By KEVIN PATRICK MCGOWAN A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2013

PAGE 2

2 2013 K evin Patrick M cGowan

PAGE 3

3 To my mother and father

PAGE 4

4 ACKNOW LEDGEMENTS I would like to start by thanking my mother and my father for their loving suppo rt and unending encouragement. You put family and education above all else, and you allowed me t o pursue my own course in life. I am truly grateful for everything yo u have given to me through I am blessed to be your son. With respect to my PhD, I thank my advisor, Dr. Adam S. Veige. Over the past five years, you have given me the opportunity to grow both as a chemist and as a leader. You pushed me to be be tter in all aspects of my work. I appreciate our long talks on chemistry, business, and life, and I appreciate all the time and effort you have devoted to me. I am proud to call myself a Veige group member. I thank all of my Veige group members, but es Sarkar, you were my mentor. You spent countless hours training me and honing my skills. You are one of the most hardworking, dedicated individuals that I have ever met. I thank you for your friendship and your s upport dur ing my research. Without you, my journey would have been far more di fficult and far less fruitful. your friendship and help with chemistry, as we navigated through the PhD journey together. I wish you the best of luck on your continued pursuit in chemistry. I would also like to thank my committee members Dr. Christou, Dr. Aponick, Dr. Murray, and Dr. Weaver for your time and input. A special thanks goes to Dr. Ghiviriga for his contribution in collecting all 2D NMR data a nd Dr. Abboud for his contribution in collecting all the X ray crystal data. Lastly, I would like to thank my roommate, Ryan, and my fianc, Jenn. Ryan, you were the best roommate and friend during my graduate years You helped me get

PAGE 5

5 through this lo ng jou rney. Jenn, you gave my life focus and direction. I thank you for your love and for always being there for me. I look forward to our life together.

PAGE 6

6 TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ................................ ................................ ............................... 4 LIST OF TABLES ................................ ................................ ................................ ............ 9 LIST OF FIGURES ................................ ................................ ................................ ........ 12 LIST OF ABBREVIATIONS ................................ ................................ ........................... 23 ABSTRACT ................................ ................................ ................................ ............... 26 CHAPTER 1 BACKGROUND INFORMATION ................................ ................................ ............ 28 1.1 Isomerization of Alkenes ................................ ................................ ................... 29 1.2 Polymerization o f Alkenes ................................ ................................ ................. 31 1.3 Polymerization of Alkynes ................................ ................................ ................. 34 1.4 Trianionic Pincer Ligands ................................ ................................ .................. 36 2 TRIANIONIC NCN 3 PINCER COMPLEXES OF CHROMIUM IN FOUR OXIDATION STATES (CR II CR III CR IV CR V ): PROGRESS TOWARDS AN ETHYLENE POLYMERIZATION CATALYSTS AND DETERMINATION OF THE ACTIVE CATALYST IN SELECTIVE 1 ALKENE TO 2 ALKENE ISOMERIZATION ................................ ................................ ................................ .... 42 2.1 Introduction ................................ ................................ ................................ ....... 42 2.2 Results and Discussion ................................ ................................ ..................... 43 2.2.1 Synt hesis of {[2,6 i PrNCN]ZnH 2 } (4). ................................ ..................... 43 2.2.2 Synthesis and Characterization of [2,6 i PrNCN]Cr III (THF) 3 (5), [2,6 i PrNCN]Cr IV Me(THF) (6), and [2,6 i PrNHCN]Cr II (THF) 2 (7). ................... 44 2.2.3 Synthesis and Characterization of [2,6 i PrNCN]Cr V (O)(THF) (8). .......... 49 2.2.4 Synthesis of [2,6 i PrNCMeN]H 2 (9) and [2,6 i PrNCBrN]H 2 (10): Attempts to synthesize [2,6 i PrNCN]Cr IV Me(THF) (6) directly. ............... 50 Isomerization of 1 Hexene and 1 Octene Using [2,6 i PrNCN]Cr IV Me(THF) (6). ................................ ................................ ................................ ......... 51 2.2.5 Mechanistic Details for the Thermolysis of [2,6 i PrNCN]Cr IV Me(THF) (6) to [2,6 i PrNDCN]Cr II (THF) 2 (7 d ). ................................ ..................... 54 2.3 Conclusions ................................ ................................ ................................ ...... 55 2.4 Experimental Section ................................ ................................ ........................ 57 2.4.1 General Considerations ................................ ................................ ......... 57 2.4.2 Analytical Techniques ................................ ................................ ............ 57 2.4.2.1 NMR techniques: ................................ ................................ ...... 57 2.4.2.2 IR techniques: ................................ ................................ ........... 58 2.4.2.3 UV Vis techniques: ................................ ................................ ... 58

PAGE 7

7 2.4.2.4 GC techniques: ................................ ................................ ......... 58 2.4.2.5 MS techniques: ................................ ................................ ......... 58 2.4.2.6 EPR techniques: ................................ ................................ ....... 58 2.4.2.7 Elemental analysis: ................................ ................................ ... 59 2.4.3 Synthesis of {[2,6 i PrNCN]ZnH 2 } (4). ................................ ..................... 59 2.4.4 Synthesis of [2,6 i PrNCN]Cr III (THF) 3 (5). ................................ ............... 59 2.4.5 Synthesis of [2,6 i PrNCN]Cr IV Me(THF) (6). ................................ ........... 60 2.4.6 Syn thesis of [2,6 i PrNHCN]Cr II (THF) 2 (7). ................................ .............. 61 2.4.7 Synthesis of [2,6 i PrNCN]Cr V (O)(THF) (8). ................................ ............ 61 2.4.8 Synthesis of 1,3 Bis(2',6' di methylphenylaminomethyl)toluene (9). ....... 61 2.4.9 Synthesis of 1,3 Bis(2',6' dimethylphenylaminomethyl) 2 bromobenzene (10). ................................ ................................ .............. 62 2.4. 10 Isomerization of 1 Hexene and 1 Octene using [2,6 i PrNCN]Cr IV Me(THF) (6). ................................ ................................ ....... 63 2.4.11 TEMPO Procedures. ................................ ................................ .............. 64 3 A NEUTRAL TRIANION IC PINCER [NCN]CR IV ME COMPLEX AS A HIGHLY ACTIVE ETHYLENE POLYMERIZATION PRECATALYST ................................ .... 78 3.1 Introduction ................................ ................................ ................................ ....... 78 3.2 Results and Dis cussion ................................ ................................ ..................... 80 3.2.1 Determination of Optimal Cocatalyst ................................ ..................... 80 3.2.2 Determination of Optimal Reaction Temperature and TIBA:6 Molar Rat io ................................ ................................ ................................ ...... 82 3.2.3 Polyethylene Characterization ................................ ............................... 83 3.3 Conclusions ................................ ................................ ................................ ...... 84 3.4 Experimental Section ................................ ................................ ........................ 86 3.4.1 General Considerations ................................ ................................ ......... 86 3.4.2 Polymerization of Ethylene using [2,6 i PrNCN]Cr IV Me(THF) (6). ........... 87 4 COMPELLING MECHANISTIC DATA AND IDENTIFICATION OF THE ACTIVE SPECIES IN TUNGSTEN CATALYZED ALKYNE POLYMERIZATIONS: CONVERSION OF A TRIANIONIC PINCER INTO A NEW TETRAANIONIC PINCER TYPE LI GAND ................................ ................................ ......................... 94 4.1 Introduction ................................ ................................ ................................ ....... 94 4.2 Results and Discussion ................................ ................................ ..................... 97 4.2.1 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). ................................ ................... 97 4.2.2 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (17 Ph). ................................ ............... 101 4.2.3 Kinetic Results of Phenylacetylene Polymerization by 15, 16 Ph, and 16 t Bu: Determination of the Active Catalyst. ................................ ....... 103 4.2.4 Polym erization Results: Monosubstituted and Disubstituted Acetylenes ................................ ................................ ........................... 104 4.2.5 Synthesis of [OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] (18A) and [OC( t BuC=)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] (18B). .......................... 108

PAGE 8

8 4.3 Conclusions ................................ ................................ ................................ .... 110 4.3.1 Formal Reductiv e Alkylidyne Migratory Insertion into a M arene Bond 110 4.3.2 Active Catalyst and Activity ................................ ................................ .. 111 4.3.3 Polymerization Mechanism ................................ ................................ .. 113 4.3.4 Effect of Substrate Choice on Polymerization ................................ ...... 114 4.4 Experimental Section ................................ ................................ ...................... 116 4.4.1 General Considerations ................................ ................................ ....... 116 4.4.2 Analytical Techniques ................................ ................................ .......... 117 4.4.2.1 NMR techniques: ................................ ................................ .... 117 4.4.2.2 IR techniques: ................................ ................................ ......... 117 4.4.2.3 GPC techniques: ................................ ................................ ..... 117 4.4.2.4 Elemental ana lysis: ................................ ................................ 118 4.4.3 Synthesis of [O 2 C( t BuC=)W( 2 t Bu). ............................ 118 4.4.4 Synthesis of [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). ............................. 119 4.4.5 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) .......................... 119 4.4.6 Synthesis of [O 2 C(PhC=)W( 2 t Bu)] (17 Ph) ........................... 120 4.4.7 Synthesis of [OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] (18A) and [OC( t BuC=)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] (18B). .......................... 121 4.4.8 Synthesis of [O 2 C(PhC=)W( 2 2 CH 3 )] (19) ........................ 122 4.4.9 Polymerization of Alkynes using [ t t Bu)(THF) 2 (15), [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). ................................ ................................ .............. 123 APPENDIX NMR, IR, UV VIS, EPR, MS, GPC, X RAY DATA ................................ .... 138 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 307

PAGE 9

9 LIST OF TABLES Table Page 1 1 Table of substrate catalyst matching for polymerization of substituted acetylenes. ................................ ................................ ................................ ......... 40 2 1 Isomerization of 1 hexene using 6 as the precatalyst ................................ ......... 71 3 1 Results of ethylene polymerization using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) ............. 90 3 2 Activity comparis on of homogeneous chromium monoalkyl based polyethylene polymerization systems. ................................ ................................ 92 3 3 Activity comparison of homogeneous chromium dialkyl based polyethylene polymerization systems. ................................ ................................ ..................... 92 3 4 Activity comparison of homogeneous chromium monochloride and dichloride based polyethylene polymerization systems. ................................ ...................... 93 3 5 Activity comparison of homogeneous chromium dinuclear and pincer type based polyethylene polymerization systems. ................................ ...................... 93 4 1 X ray crystallographic structure parameters and refinement data. ................... 127 4 2 Acetylene polymerization results using 15 ................................ ........................ 131 4 3 Acetylene polymerization results using 16 t Bu ................................ ................. 132 4 4 Optimized polymerization results using 16 t Bu ................................ ................. 135 A 1 Assignment of 1 H and 13 C chemical shifts for 16 t Bu and 16 Ph in toluene d 8 at 25 C. ................................ ................................ ................................ ........... 154 A 2 Assignment of 1 H and 13 C chemical shifts for 17 t Bu and 17 Ph in toluene d 8 at 25 C. ................................ ................................ ................................ ........... 164 A 3 Assignment of 1 H and 13 C chemical shifts for 1 8A and 18B in toluene d 8 at 25 C. ................................ ................................ ................................ ............... 173 A 4 Assignment of 1 H and 13 C chemical shifts for 19 in toluene d 8 at 25 C. .......... 180 A 5 RAD h igh temperature GPC results summary for ethylene polymerization runs using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ......................... 211 A 6 Crystal data, structure solution and refinement for 4 ................................ ....... 236 A 7 Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 4 ................................ ................................ ................................ .. 237

PAGE 10

10 A 8 Bond lengths (in ) for 4 ................................ ................................ .................. 239 A 9 Bond angles (in deg) for 4 ................................ ................................ ............... 240 A 10 Anisotropic displacement parameters (2x 103) for 4. ................................ ..... 242 A 11 Crystal data, structure solution and refinement for 6 ................................ ....... 246 A 12 Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 6 ................................ ................................ ............. 247 A 13 Bond lengths (in ) for 6 ................................ ................................ .................. 248 A 14 Bond angles (in deg) for 6 ................................ ................................ ............... 249 A 15 Crystal data and structure refinement for 16 Ph ................................ .............. 252 A 16 Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 16 Ph .. ................................ ................................ .... 253 A 17 Bond lengths () for 16 Ph ................................ ................................ .............. 255 A 18 Bond angles (in deg) for 16 Ph ................................ ................................ ........ 256 A 1 9 Anisotropic displacement parameters ( 2 x 10 3 ) for 16 Ph .. ........................... 258 A 20 Crystal data and structure refinement for 17 Ph ................................ .............. 262 A 21 Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 17 Ph ................................ ................................ ....... 263 A 22 Bond lengths (in ) for 17 Ph ................................ ................................ .......... 265 A 23 Bond angles (in deg) for 17 Ph ................................ ................................ ........ 266 A 24 Anisotropic displacement parameters ( x 10 3 ) for 17 Ph ............................... 268 A 25 C rystal data and structure refinement for 18A ................................ ................. 272 A 26 Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 18A .. ................................ ................................ ........ 273 A 27 Bond lengths (in ) for 18A ................................ ................................ ............. 275 A 28 Bond angles (in deg) for 18A ................................ ................................ ........... 276 A 29 Anis otropic displa cement parameters ( 2 x 10 3 ) for 18A ................................ 278

PAGE 11

11 A 30 Crystal data and structure refinement for 19 ................................ .................... 282 A 31 Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 19 .. ................................ ................................ ........... 283 A 32 Bond lengths (in ) for 19 ................................ ................................ ................ 285 A 33 Bond angles ( in deg) for 19 ................................ ................................ ............. 286 A 34 Aniso tropic displacement parameters ( 2 x 10 3 ) for 19 .. ................................ ... 288

PAGE 12

12 LIST OF FIGURES Figure Page 1 1 Selective isomerization of 6 methyl 6 hepten 2 one. ................................ .......... 38 1 2 Transition metal catalyzed isomerization pathways. ................................ ........... 38 1 3 Examples of classes of homogeneous Cr III based precatalysts/catalysts for ethylene polymerization. ................................ ................................ ..................... 38 1 4 Half sandwich chromium polymerization catalysts. ................................ ............. 39 1 5 Two known homogeneous Cr IV alkyl complexes that polymerize ethylene. ........ 39 1 6 Polymerization of acetylene and its analogues. ................................ .................. 39 1 7 The NCN trianionic pincer ligand with amide arylide amide donors ( 1 ), and the OCO trianionic pincer ligand exists with phenoxide arylide phenoxide donors ( 2 ). ................................ ................................ ................................ .......... 40 1 8 Traditional pincer ligands ................................ ................................ .................... 40 1 9 Pincer ligand architectures. ................................ ................................ ................ 41 2 1 Formation of {[2,6 i PrNCHN] Zn} 2 ( 4 ). ................................ ................................ .. 64 2 2 Ortep drawings of the molecular structure of {[2,6 i PrNCHN]Zn} 2 ( 4 ) with ellipsoids drawn at the 50% probability level and hydrogen removed for clarity.. ................................ ................................ ................................ ................ 65 2 3 Truncated view of 4 highlighting the two coordinate Zn ions and the 16 membered Z shaped metallocycle. ................................ ................................ ..... 66 2 4 Space filling drawing of the structure of {[2,6 i PrNCHN]Zn} 2 ( 4 ). ........................ 66 2 5 Three trianionic NCN 3 pincer ligand chromium complexes ( 5 6 and 7 ) form by treating CrMeCl 2 (THF) 3 with {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in diethyl ether at 80 C. ................................ ................................ ................................ ...................... 67 2 6 Exclusive formation of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) using THF as the solvent. ..... 67 2 7 Molecular structure of [2,6 i PrNCN]Cr IV Me(THF) ( 5 ) with ellipsoids presented at the 50% probability level and hydrogen atoms removed for clarity. ................ 68 2 8 Treating anhydrous CrCl 2 with {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in THF at 80 C provides [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ). ................................ ................................ 68

PAGE 13

13 2 9 Treating 5 with styrene oxide in THF at 35 C provides the Cr V (O) complex [2,6 i PrNCN]Cr V (O)( THF) ( 8 ). ................................ ................................ ............. 69 2 10 EPR spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) (2.5 mM solution, toluene) at T = 20 K. ................................ ................................ ................................ ............. 69 2 11 Synthesis of [2,6 i PrNCMeN]H 2 ( 9 ). ................................ ................................ .... 70 2 12 Synthesis of [2,6 i PrNCBrN]H 2 ( 10 ). ................................ ................................ ... 70 2 13 Transient 1 H NMR spectra obtained in benzene d 6 of [ 2,6 i Pr NCN]Cr IV Me(THF) ( 6 ) in solution with 1 hexene; progress of the isomerization. ................................ ................................ ................................ ..... 71 2 14 Catalytic % conversion of 1 hexene and 1 octene versus time with 6 as the precatalyst in C 6 D 6 at 85 C. ................................ ................................ ............... 72 2 15 Catalytic % conversion of 1 hexene upon preheating 6 to 85 C for 24 h, followed by substrate addition. ................................ ................................ ........... 73 2 16 Proposed c onversion of precatalyst Cr IV ( 6 ) to the active catalyst Cr II ( 7 d ). ...... 73 2 17 Catalytic % conversion of 1 hexene by 7 in C 6 D 6 at 85 C. ................................ 74 2 18 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with D 2 O. ................................ ................................ ............... 74 2 19 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with H 2 O. ................................ ................................ ............... 75 2 20 heating [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) for 48 h at 85C. ................................ ...... 75 2 21 Proposed mechanism for thermolysis of 6 to form CH 4 and (C 6 D 5 ) 2 .................. 76 2 22 Proposed mechanism for thermolysis of 6 in the presence of TEMPO. .............. 76 2 23 Formation of 7 ( 7 d ) via salt metathesis or thermolysis of 6 featuring a common intermediate. ................................ ................................ ........................ 77 3 1 Examples of classes o f homogeneous Cr III based precatalysts/catalysts for ethylene polymerization. ................................ ................................ ..................... 88 3 2 Two known homogeneous Cr IV alkyl complexes that polymerize ethylene. ........ 88 3 3 [Cp*Cr(THF) 2 Me]BPh 4 catalyst compared to the neutral 14 e [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (1; Ar = 2,6 bis(1 methylethyl)phenyl). ................................ ................................ ........................... 88

PAGE 14

14 3 4 Reactions between B(C 6 F 5 ) 3 and zirconocene dimethyl complex to provide cationic alkylzirconocene methyltriarylborate complex via methide abstraction. ................................ ................................ ................................ ......... 89 3 5 Methyl abstraction by B(C 6 F 5 ) 3 ................................ ................................ .......... 89 3 6 Relative acidity ordering of common cocatalyst activators. 222 ............................. 89 3 7 Activity (kg PE (molCr) 1 h 1 ) for complex 6 versus TIB 6 6 ................................ ................................ ............................. 91 3 8 13 C NMR of polyethylene sample in 1,3,5 trichlorobenzene d 3 at 130 C. .......... 91 4 1 Precatalyst [ t 3 ) 3 )(THF) 2 ( 15 ). ................................ ............... 124 4 2 Full synthetic scheme for the synthesis of [ t t Bu)(THF) 2 ( 15 ). ...... 124 4 3 Proposed ring expansion polymerization of alkynes. ................................ ........ 124 4 4 Illustration of how trianionic pincer ligands can facilitate coordination of a second alkyne. ................................ ................................ ................................ .. 125 4 5 New tretranionic pincer type ligand [O 2 C(R)C=] 4 R = Ph, t Bu. ........................ 125 4 6 Synthesis of 16 t Bu and 16 Ph supported by the tetraanionic pincer type ligand [O 2 C(RC=)W( 2 t Bu)] (R = t Bu, Ph). ................................ ............. 125 4 7 Molecular structure of 16 Ph with ellipsoids present at 50% probability. .......... 126 4 8 Ca nonical forms of 2 H .. 127 4 9 Equilibrium reaction between 16 t Bu (kinetic product) and 16 Ph (thermodynamic product) at 85 C, toluene d 8 ................................ ................. 128 4 10 Concentration of conversion of 16 t Bu into 16 Ph vs. time. ............................. 128 4 11 Integrated rate law for a reversible first order react ion for the conversion of 16 t Bu into 16 Ph vs time (h).. ................................ ................................ .......... 129 4 12 Plots of the ln[ 16 t Bu ] (red) and ln[ 16 Ph ] (blue) vs time. ................................ 129 4 13 Synthesis of 17 t Bu and 17 Ph supported by the tetraanionic pincer type ligand [O 2 C(RC=)W( 2 t Bu)] (R = t Bu, Ph). ................................ ............ 130 4 14 Molecular structure of 17 Ph with ellipsoids presented a t 50% probability and hydrogen atoms removed for clarity.. ................................ ............................... 130 4 15 Catalytic TON determined by quantitative yield (mg) of PPA vs. time (min) for 15 16 t Bu and 16 Ph .. ................................ ................................ .................... 131

PAGE 15

15 4 16 18A and 18B ................................ ................................ ................................ .................. 132 4 17 Molecular structure of 18A with ellipsoids presented at 50% probability and hyd rogen atoms removed for clar ity ................................ ................................ 133 4 18 Two possible routes to the overall formal reductive alkylidyne migratory insertion.. ................................ ................................ ................................ .......... 134 4 19 Truncated X ray stru ctural data ( 18A ) highlighting the meridional coordination of the tetraanionic pincer type ligand [O 2 C( t BuC=)] 4 ................................ ....... 134 4 20 Proposed mechanism for polymer chain growth. ................................ .............. 135 4 21 Molecular structure of 19 with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. ................................ ................................ 136 4 22 Addition of HCCPh( p NO 2 ) to 15 to form a tungsten alkylidene ( 20 ). This structure is not fully elucidated. ................................ ................................ ........ 137 4 23 Catalytic activation of 15 by HCCPh( p NO 2 ) and heating of 15 to form 20 ...... 137 A 1 1 H NMR spectrum of {[2,6 i PrNCHN]Zn} 2 ( 4 ) in benzene d 6 ............................ 138 A 2 13 C{ 1 H} NMR spectrum of {[2,6 i PrNCHN]Zn} 2 ( 4 ) in benzene d 6 ..................... 139 A 3 1 H NMR spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) obtained in benzene d 6 ....... 140 A 4 1 H NMR spectrum of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) obtained in b enzene d 6 ... 141 A 5 1 H NMR spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ) obtained in benzene d 6 ..... 142 A 6 1 H NMR spectrum of [2,6 i PrNCN ]Cr V (O)(THF) ( 8 ) obtained in benzene d 6 .... 143 A 7 1 H NMR spectrum of [2,6 i PrNCMeN]H 2 ( 9 ) obtained in benzene d 6 ............... 144 A 8 13 C NMR spectrum of [2,6 i PrNCMeN]H 2 ( 9 ) obtained in benzene d 6 .............. 145 A 9 1 H NMR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ) obtained in benzene d 6 .............. 146 A 10 13 C NMR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ) obtained in benzene d 6 ............. 147 A 11 1 H NMR spectrum of 16 t Bu in C 6 D 6 at 25 C. ................................ .................. 148 A 12 13 C NMR spectrum of 16 t Bu in C 6 D 6 at 25 C, expansion of the aliphatic region. ................................ ................................ ................................ .............. 149 A 13 13 C NMR spectrum of 16 t Bu in C 6 D 6 at 25 C, expansion of the aromatic region. ................................ ................................ ................................ .............. 150

PAGE 16

16 A 14 1 H NMR spectrum of 16 Ph in C 6 D 6 at 25 C. ................................ ................... 151 A 15 13 C NMR spectrum of 16 Ph in C 6 D 6 at 25 C, expansion of the aliphatic region. ................................ ................................ ................................ .............. 152 A 16 13 C NMR spectrum of 16 Ph in C 6 D 6 at 25 C, expansion of the aromatic region. ................................ ................................ ................................ .............. 153 A 17 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 ........................... 155 A 18 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion of the aliphatic region. ................................ ................................ ................................ 155 A 19 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion of the aromatic region. ................................ ................................ ................................ 156 A 20 1 H 13 C gHSQC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 ....... 156 A 21 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 157 A 22 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 157 A 23 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 158 A 24 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 158 A 25 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 159 A 26 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 159 A 27 1 H NMR spectrum of 17 t Bu in C 6 D 6 at 25 C. ................................ .................. 160 A 28 1 H NMR spectrum of 17 Ph in C 6 D 6 at 25 C. ................................ ................... 161 A 29 13 C NMR spectrum of 17 Ph in C 6 D 6 at 25 C, expansion of the aliphatic region. ................................ ................................ ................................ .............. 162 A 30 13 C NMR spectrum of 17 Ph in C 6 D 6 at 25 C, expansion of the aromatic region. ................................ ................................ ................................ .............. 163 A 31 1 H spectr um of mixture of 17 t Bu and 17 Ph in toluene d 8 ............................... 165

PAGE 17

17 A 32 1 H spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion of the aliphatic region. ................................ ................................ ................................ 165 A 33 1 H spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion of the aromatic region. ................................ ................................ ................................ 166 A 34 1 H 13 C gHSQC spectrum of mixture of 17 t Bu and 17 Ph in tol uene d 8 expansion of the aliphatic region. ................................ ................................ ..... 166 A 35 1 H 13 C gHSQC spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 167 A 36 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 ....... 167 A 37 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 168 A 38 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 168 A 39 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 169 A 40 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 169 A 41 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 170 A 42 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ................................ ........ 170 A 43 1 H 13 C gHMBC spectrum (optimized for 4 Hz) of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. ................................ ................................ ............. 171 A 44 ROESY spectrum of a mixtu re of 17 t Bu and 17 Ph in toluene d 8 expansion. 171 A 45 ROESY spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. 172 A 46 ROESY spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. 172 A 47 1 H 1 H gDQF COSY spectrum of mixture of 18A and 18B in toluene d 8 .......... 174 A 48 1 H 13 C gHSQCAD spectrum of mixture of 18A and 18B in toluene d 8 ............. 174 A 49 1 H 13 C gHSQCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 175

PAGE 18

18 A 50 1 H 13 C gHSQCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 175 A 51 1 H 13 C gHMBCAD spectrum of mixtur e of 18A and 18B in toluene d 8 ............ 176 A 52 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 176 A 53 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 177 A 54 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 177 A 55 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. ................................ ................................ ................................ ........ 178 A 56 1 H NMR spectrum of 19 in toluene d 8 ................................ .............................. 179 A 57 1 H NMR spectrum of 19 in benzene d 6 ................................ ............................ 181 A 58 1 H NMR spectrum of 19 in benzene d 6 expansion of the aliphatic region. ....... 181 A 59 1 H NMR spectrum of 19 in benzene d 6 expansion of the aromatic region. ...... 182 A 60 1 H 13 C gHSQC spectrum of compound 19 in benzene d 6 ................................ 182 A 61 1 H 13 C gHMBC spectrum of 19 in benzene d 6 ................................ ................. 1 83 A 62 1 H 13 C gHMBC spectrum of 19 in benzene d 6 expansion. ............................... 183 A 63 1 H 1 H ROESY spectrum of 19 in benzene d 6 ................................ .................. 184 A 64 1 H 1 H ROESY spectrum of 19 in benzene d 6 expansion. ................................ 184 A 65 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 ...................... 185 A 66 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of the aromatic region ................................ ................................ .......................... 185 A 67 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 ........... 186 A 68 1 H 13 C gHMBC spectrum of 15 + 4 nitrophe nylacetylene in toluene d 8 expansion of aliphatic region. ................................ ................................ ........... 186 A 69 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of aliphatic region. ................................ ................................ ........... 187

PAGE 19

19 A 70 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of aliphatic region. ................................ ................................ ........... 187 A 71 1 H NMR spectrum of 15 + 4 nitropheny lacetylene in cyclohexane d 12 ............ 188 A 72 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion of aromatic region. ................................ ................................ ........... 188 A 73 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion of aliphatic region. ................................ ................................ ........... 189 A 74 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 .. 189 A 75 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. ................................ ................................ ................................ ........ 190 A 76 1 H 13 C gHMBC spectru m of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. ................................ ................................ ................................ ........ 190 A 77 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. ................................ ................................ ................................ ........ 191 A 78 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. ................................ ................................ ................................ ........ 191 A 79 1 H spectrum of 15 in pentafluoropyridine. ................................ ......................... 192 A 80 1 H spectrum of 15 in pentafluoropyridine, expansion of aromatic region. ......... 192 A 81 1 H 13 C gHMBC spectrum of 15 in pentafluoropyridine. ................................ ..... 193 A 82 1 H 13 C gHMBC spectrum of 15 in pentafluoropyridine, expansion of aromatic region. ................................ ................................ ................................ .............. 193 A 83 1 H spectrum of 15 + 4 nitrophenyl acetylene in pentafluoropyridine. ................. 194 A 84 1 H spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine, expansion of aromatic region. ................................ ................................ ............................ 194 A 85 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine. ................................ ................................ .......................... 195 A 86 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine, expansio n of aromatic region. ................................ .......... 195 A 87 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine, expansion of aromatic region. ................................ .......... 196 A 88 1 H NMR of PPA derived from the phenylacetylene monomer. .......................... 197

PAGE 20

20 A 89 1 H NMR of PPA derived from the 1 ethynyl 4 fluorobenzene monomer. .......... 197 A 90 1 H NMR of PPA derived from the 1 ethynyl 4 methoxybenzene monomer. ..... 198 A 91 IR spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ). ................................ ...................... 199 A 92 IR spectrum of [2,6 i PrNCN]CrMe IV (THF) ( 6 ). ................................ ................... 199 A 93 IR spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ). ................................ ..................... 200 A 94 IR spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ). ................................ ................... 200 A 95 IR spectrum of [2,6 i PrNCMeN]H 2 ( 9 ). ................................ .............................. 201 A 96 IR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ). ................................ ............................. 201 A 97 IR spectrum of poly(phenylacetylene). ................................ ............................. 202 A 98 IR spectrum of poly(fluorophenylacetylene). ................................ ..................... 202 A 99 IR spectrum of poly( methoxyphenylacetylene ). ................................ ................ 203 A 100 UV vis spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) in benzene. ............................. 204 A 101 UV vis spectrum of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) in pentane. .......................... 205 A 102 UV vis spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ) in pentane. ............................ 206 A 103 UV Vis spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) in benzene. ......................... 207 A 104 EPR spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) ( 2.5 mM solution, toluene) at T = 20 K. ................................ ................................ ................................ ........... 208 A 105 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with D 2 O. ................................ ................................ ............. 209 A 106 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with H 2 O. ................................ ................................ ............. 210 A 107 GPC chromatogram for ethylene polymerization runs using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 212 A 108 DSC curve for ethylene polymerization run 7 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ ................................ .................... 213 A 109 DSC curve for ethylene polymerization run 8 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ ................................ .................... 214

PAGE 21

21 A 110 DSC curve for ethylene polymerization run 9 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ ................................ .................... 215 A 111 DSC curve for ethylene polymerization run 10 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 216 A 112 DSC curve for ethylene polymerization run 13 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 217 A 113 DSC curve for ethylene polymerization run 14 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 218 A 114 DSC curve for ethylene polymerization run 15 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 219 A 115 DSC curve for ethylene polymerization run 16 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 220 A 116 DSC curve for ethylene polymerization run 18 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 221 A 117 DSC curve for ethylene polymerization run 19 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 222 A 118 DSC curve for ethylene polymerization run 20 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 223 A 11 9 DSC curve for ethylene polymerization run 21 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 224 A 120 DSC curve for ethylene polymerization run 22 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 225 A 121 DSC curve for ethylene polymerization run 23 using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ .................. 226 A 122 DSC curve for ethylene polymerization run 24 usi ng 2,6 i PrNCN]Cr IV Me(THF) ( 6 ). ................................ ................................ ................................ .................... 227 A 123 GPC chromatogram for polymer of phenylacetylene using 15 ......................... 228 A 124 GPC chromatogram fo r polymer of 1 ethynyl 4 methoxybenzene using 15 .... 228 A 125 GPC chromatogram for polymer of 1 ethynyl 4 fluorobenzene using 15 ......... 229 A 126 GPC chromatogram for polymer of 1 ethynyl 3,5 bis(trifluoromethyl)benzene using 15 ................................ ................................ ................................ ........... 229 A 127 GPC chromatogram for polymer of 1 decyne using 15 ................................ .... 230

PAGE 22

22 A 128 GPC chromatogram for polymer of 3,3 dimethyl 1 butyne using 15 ................ 230 A 129 GPC chromatogram for polymer of phenylacetylene using 16 t Bu .................. 231 A 130 GPC chromatogram for polymer of 1 ethynyl 4 methoxybenzene using 16 t Bu ................................ ................................ ................................ ................... 231 A 131 GPC chromatogram for polymer of 1 ethynyl 4 fluorobenz ene using 16 t Bu .. 232 A 132 GPC chromatogram for polymer of 1 ethynyl 3,5 bis(trifluoromethyl)benzene using 16 t Bu ................................ ................................ ................................ .... 232 A 133 GP C chromatogram for polymer of 1 decyne using 16 t Bu ............................. 233 A 134 GPC chromatogram for polymer of 3,3 dimethyl 1 butyne using 16 t Bu ......... 233 A 135 Molecular structure of 4 with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. ................................ ................................ 234 A 136 Molecular structure of 6 with ellipsoids presented at 50% p robability and hydrogen atoms removed for clarity. ................................ ................................ 244 A 137 Molecular structure of 16 Ph with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. ................................ ................................ 250 A 138 Molecular structure of 17 Ph with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. ................................ ................................ 260 A 139 Molecular s tructure of 18A with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. ................................ ................................ 270 A 140 Molecular structure of 19 with ellipsoids presented at 50% probability and hydrog en atoms removed for clarity. ................................ ................................ 280

PAGE 23

23 L IST O F ABBREVIATIONS DPPH 2,2 diphenyl 1 picrylhydrazyl TEMPO 2,2,6,6 tetra methylpiperidin 1 yl)oxyl OCO di tert butyl terphenyl] diol C 6 H 6 benzene C 6 D 6 benzene d6 n BuLi n butylithium CO carbon monoxide Da Daltons (C 6 D 5 ) 2 deuterated biphenyl Et 2 AlCl diethylaluminum chloride Et 2 O diethyl ether DSC differential scanning calorimetry EPR electron paramagnetic resonance ESI TOF electron spray ionization time of flight FT IR fourier transform infrared GC gas chromatography GPC gel permeation chromatography gDQF COSY gradient double quantum filtered COSY gHMBC gradient heteronuclear multiple bond coherence gHMBCAD gradient heteronuclear multiple bond correlation with adiaba tic pulse gHSQC gradient heteronuclear single quantum coherence gHSQCAD gradient heteronuclear single quantum correlation with adiabatic pulse g gram HDPE high density polyethylene

PAGE 24

24 h hours IR infrared i Pr isopropyl kg kilogram MS mass spectrometry CH 4 meth ane Me methyl MAO methylaluminoxane Ph 3 P=CH 2 methylene(triphenyl)phosphorane microliter micromol mg milligram mmol millimol min minute MMAO modified methylaluminoxane mol mol NCN (1,3 phenylenebis(methylene))diarylamine NMR nuclear magnetic re sonance OA oxidative addition Ph phenyl P 4 O 10 phosphorus pentoxide PA polyacetylene PE polyethylene PPA poly(phenylacetylene) ppm parts per million

PAGE 25

25 ROESY rotating frame nuclear Overhauser effect spectroscopy tBu tert butyl THF tetrahydrofuran AlR 3 trialkyl aluminum TIBA triisobutylaluminum PPh 3 triphenylphosphine PPh 3 O triphenylphosphine oxide B(C 6 F 5 ) 3 tris(pentafluorophenyl)borane FAB tris(pentafluorophenyl)borane TEM tunneling electron microscope TOF t urnover frequency TON turnover number

PAGE 26

26 Abstract of Dis sertation Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy TRIANIONIC NCN 3 PINCER COMPLEX OF CHROMIUM AND TETRA A NIONIC OCO 4 PINCER COMPLEX OF TUNGSTEN: PRE CATAL YSTS/CATALYSTS FOR ALKENE AND ALKYNE POLYMERIZATIO N By Kevin McGowan May 2013 Chair: Adam S. Veige Major: Chemistry This dissertation details the synthesis of 1) a trianionic NCN pincer supported Cr IV methyl complex and its applicatio n as an alkene polymerization pre catalyst and 2) two tetraanionic OCO pincer supported W VI metallocyclopropene compl exes and their application as alkyne polymerization catalysts. The synthesis of the NCN Cr IV methyl complex [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) occ urs by treating CrMeCl 2 (THF) 2 with the dilithio salt pincer ligand precursor {[2,6 i PrNCHN]Li 2 } 2 ( 3 ). The main product s of the reaction are Cr III [2,6 i PrNCN]Cr III (THF) 3 ( 5 ), Cr IV ( 6 ) and Cr II [2,6 i PrNHCN ] Cr II (THF) 2 complex es ( 7 ). Complex 6 is a rare exam ple of a Cr IV methyl complex that is stable at 25 C. However, at 85 C, the Cr Me bond undergoes homolysis. The metal containing product from the thermolysis is the same Cr II ( 7 ) formed during the metallation, except the proton on one nitrogen is substitu ted for a deuterium atom ( 7 d ). The Cr II species actively catalyz es the selective isomerization of 1 alkenes to 2 alkenes. The NCN Cr IV methyl complex [2,6 i PrNCN]Cr IV Me(THF) ( 6 ), upon activation by triisobutylaluminum (TIBA), catalyzes the polymerization 6 polymerizes ethylene with an activity of 7.02 x 10 6 g PE(molCr) 1 h 1 (75 C). Based on

PAGE 27

27 the large polydispersities of the polyethylene, multiple active sites are operable and complex 6 most likely only acts as a pre catalys t. Two tetraanionic OCO pincer supported W VI metallocyclopropene complexes form upon treating [ t BuOCO]W C( t Bu)(THF) 2 ( 15 ) with 2 equiv. of phenylacetylene in toluene d 8 at 35 C. These two products are [O 2 C( t BuC=)W( 2 HC CPh)] ( 16 t Bu ) and {[O 2 C(PhC=)W( 2 HC C t Bu)] ( 16 Ph ) {where OC( t BuC=)O = [2,6 ( t BuC 6 H 3 O) 2 C 6 H 3 ( t BuC )] 4 OC(PhC=)O = [2,6 ( t BuC 6 H 3 O) 2 C 6 H 3 (PhC )] 4 Complexes 16 t Bu and 16 Ph are the active catalysts for the polymerization of acetylenes. They polymerize a wide variet y of acetylenes. With a substrate to catalyst loading ratio of 25,000 to 1, complex 16 t Bu polymerizes phenylacetylene and 1 decyne with catalytic activities up to 5.64 x 10 6 g PPA mol 1 h 1 and 7.98 x10 6 g PA mol 1 h 1 respectively. Treating 16 t Bu with 10 equiv. of MeC CPh in toluene d 8 at 75 C selectively incorporate s one additional acetylene unit The MeC CPh inserts into the metallocyclopropene to form a metallocyclopentadiene ring. The insertion yields two isomers, [ OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] ( 18A ) and [OC( t BuC =)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] ( 18B ) Complexes 18A and 18B provide reasonable evidence for an insertion/ring expansion polymerization mechanism for chain propagation.

PAGE 28

28 CHAPTER 1 BACKGROUND INFORMATION The synthesis of polymers is of great academic value a nd industrial implication. Commercially available synthetic plastics, such as polyethylene, polypropylene, and polystyrene, play an indispensable and ubiquitous role in everyday modern life. These materials are components in everything from bags to packagi ng, wire coatings, and textiles. 1 Overall, approximatel y 100 million tons of polyethylene and its derivatives are currently manufactured on an annual basis. 2 In comparison to above refer enced polymers formed using olefins (monomers with double bonds), polymers formed using acetylene and its derivatives (monomers with triple bonds) are not industrially produced. Nevertheless, polymers of acetylene and its derivatives are of great interest because polyacetylenes (PA) and its derivatives possess a backbone with conjugated carbon carbon double bonds. 2 This unique electron ic structure endows these polymers with distinctive properties that are extremely difficult, if not impossible, to access with electronically saturated polymers. This dissertation focuses on the development and exploration of homogenous Group VI catalysts capable of polymerizing alkenes or alkynes. Homogeneous metal catalysis is an increasingly important area of organometallic and industrial chemistry. By promoting chemical transformations that produce chemically higher value molecules, homogeneous catalysi s achieves a major goal of modern chemistry. Despite the growth of homogeneous catalysis in the latter half of the 20th century, the term catalysis prior to the 1950s was linked to heterogeneously catalyzed large volume industrial chemical processes (amm onia synthesis, coal hydrogenation, fat hardening, Fischer Tropsch synthesis, mineral oil processing). 3 Heterogeneous catalys ts were and still are more

PAGE 29

29 widely employed in indust ry especially in the production of polyethylene, because of their wider scope, ease of separation from products, higher thermal stability and ability to be recycled. In fact, roughly 85% of all catalytic processes are currently based on heterogeneous cat alysts. 4 While heterogeneous catalysts offer certain industrial advantages, homogen eous catalysis offer s distinct advantages, which explains its increasing importance and use both f rom an academic and industrial perspective. The discrete nature of homogeneous catalysts typically allows for a far better mechanistic understanding of the chemical transformatio ns that occur during a catalytic process. Additionally, by controlling the arc hitecture created by the geometry of the ligands as well as the steric and electronic properties, it is possible to tailor optimized homogenous catalysts to th e particular problem involved. These catalysts thus possess the potential to be more reactive and more regio and stereoselective than heterogeneous catalysts. 1 One main area of interest of homogeneous metal catalysis is the interaction between alkenes and transition metal catalysts and between alkynes and transition metal catalysts. This includes polymerization and double bond isomerization of alkenes an d polymerization of alkynes. The novelty of this work is the development of coordinatively and electronically unsaturated homogenous Group VI metal complexes supported by a trianionic or tetraanionic pincer ligand and exploration of their ability to polyme rize either alkenes or alkynes. 1.1 Isomerization of Alkenes One important role of organometallic complexes is their use as homogenous catalysts for isomerization of functionalized substrates in organic reactions. Among these the isomerization of alkenes cons titutes one of the mo st important types of

PAGE 30

30 transformations Specifically, 1 alkene isomerization is a key step in many industrial processes, particula rly in petrochemical refining. For example, d ouble bond isomerization catalysis is utilized in the Shell h igher olefin process (SHOP) as well as to adiponitrile synthesis. 3 In the BASF synthesis of vitamin A the olefin is obtained from the isomeriza tion of 6 methyl 6 hepten 2 one ( Figure 1 1 ). 5 Therefore selective olefin isomerization under mild conditions is an important goal. Transition metal catalyzed isomerization of terminal olefins has been extensively studied, and two major mechanisms exist depending on the specific nature of the metal complex. Metal hydrides (Ni, Ir, Ru, Rh) or complexes capable of accessing a metal hydride via a proton source 6 11 operate via a metal hydride addition elimination pathway with a 1,2 hydrogen migration ( Figure 1 2 A). On the other hand, metal complexes withou t a metal hydride or complexes incapable of accessing a metal hydride via a proton source, such as Fe and Ru carbonyl and phosphine substituted carbonyl derivatives, 12 16 isomerize 1 allyl intermediate. metal hydride intermediate mechanism involves a 1,3 hydrogen shift ( Figure 1 2 B ). The isomerization of a terminal double bond to an internal double bond is thermodynamically favored because intern al alkenes are more stable than terminal alkenes. Furthermore, thermodynamics favors alkenes with the double bond farther from the end of the carbon chain. For example, the equilibrium isomerization of 1 octene yields a mixture containing 2% 1 octene, 36% 2 octene, 36% 3 octene, and 26% 4 octene ( cis / trans mixtures). 17 As thermodynamically expected, a majority of the catalysts that isomerize terminal double bonds provide the near ther modynamically

PAGE 31

31 predicted equilibrium mixture of isomeric alkenes. Therefore, these catalysts offer little in the way of selectivity. Enhanced selectivity for the isomerization of 1 alkenes to 2 alkenes has been achieved by forming conjugated diene products 18 However, only a few examples of highly selective alkene isomerization catalysts exist that do not depend on the formation of a conjugated product. Specifically, organotitanium 19 or titanocene and zirconocene 20 alkyne derivatives have been shown to selectively iso merize 1 alkenes to 2 alkenes. Examples include the titanocene complexes [Cp 2 Ti(Me 3 3 )], [Cp 2 Ti(Me 3 t Bu)], and [Cp 2 Ti(Me 3 plex es [Cp 2 Zr(thf)(Me 3 3 )] and [Cp 2 Zr(py)(Me 3 3 )] as precatalysts which generate titanocene and zirconocene as the active catalytic species. These highly selective 1 alkene isomerization active catalysts are coordinatively unsaturated and sterically unhindered ear ly transition metal complexes. Early transition metal pincer complexes offer the possibility to provide coordinatively uns aturated and sterically unhindered metal centers capable of selective 1 alkene isomerization. 1.2 Polymerization of Alkenes Polymers produced by the polymerization of small olefins such as ethylene are among the most widely used organic materials. The growing application of polyolefins can be attributed to the fact that they only contain hyd rogen and carbon, are ine rt, stable to water, and can be recycled. With the exception of low density polyethylene (LDPE), which is produced via radical processes, a majority of polyethylene especially high density polyethylene (HDPE), is the product of metal catalyzed reactions. Two classes of early transition metal (Group III VI) catalysts are commonly used. The first class utilizes group 4 metals (Ti, Zr) and is derived from the discoveries of Zeigler and

PAGE 32

32 Natta. 21 23 These catalysts are solid supported titanium catalysts, which are typically prepared by combining titanium or zirconium chlorides with an aluminum alkyl co catalyst. 24 The second class utilizes chromium and is based upon silica supported chromium oxide (CrO 3 /SiO 2 ) deve loped by Phillips Petroleum Co. 25,26 or silica supported chromacene (Cp 2 Cr/SiO 2 ) developed by Union Carbide. 27,28 These systems are notable f or not requiring a co catalyst. Phillips catalyst is among the most widely used catalysts for the worldwide production of high density polyethylene (HDPE), accounting for one third of global production. Since heterogeneous catalysts are difficult to study, ongoing debate exist s about the oxidation state and identity of the active chromium species in the Phillips catalyst. In fact, the identity of the active form of the Phillips catalyst has been the center of debate for more than fifty years. 29 Oxidation states ranging from Cr(II) to Cr(IV) have been claimed to be the oxidation state of the a ctive catalyst. However, no one oxidation state has been accepted by the community. In pursuit of informative models of the Phillips catalyst, a multitude of homogenous chromium catalysts, a majority of which are half sandwich systems have been developed to better understand the active form in the Phillips catalyst. An overwhelming majority of these homogenous chromium based precatalysts/catalysts exist in the 3+ oxidation state. 30 These homogeneous chromium based precatalysts/catalysts include cati onic Cr III monoalkyls 31 35 or neutral Cr III monoalkyl complexes, 36 39 Cr III dialkyls, 32,40 43 and Cr III mono 37,44 48 or dichloride species. 32,40,49 58 ( Figure 1 3 ).

PAGE 33

33 The common structural feature of the reported models is an alkyl group bonded to chromium or chromium complex capable of accessing suc h a st ructure upon activation. For example, the cationic chromium complex [Cp*Cr(THF) 2 Me]BPh 4 59,60 shown in Figure 1 4 ( A ) catalyzes the polymerization of ethylene at ambient temperature and press ure, without added cocatalyst. The amino substituted cyclopentadienyl chromium derivative 61 in Figure 1 4 ( B ) must be activated with methylaluminumoxane prior to polymerizing ethylene. An active species with chromiu m alkyl is considered a requirement because the generally accepted mechanism of polymer chain growth involves the coordination of ethylene to a metal with alkyl group, followed by migratory insertion of the olef in into the metal carbon bond. This increases the length of t he alkyl chain by two carbons. Additional common properties for these homogeneous chromium catalysts include coordinately and electronically unsaturated chromium metal centers able to coordinate ethylene with ligand architectures resistant to dimerization. In comparison to the multitude of homogenous Cr III precatalysts/catalysts for ethylene polymerization, there are only a few Cr IV models that possess a chromium alkyl bond and polymerize ethylene. In fact, only two homoleptic Cr IV R 4 (R=CH 2 C(CH 3 ) 3 and CH 2 Si(CH 3 ) 3 ) complexes 62 ( Figure 1 5 ) along with a few silica supported Cr IV alkyls 63 67 are known. Trianionic pincer ligands allow for the synthesis of a coordi natively and electronically unsaturated chromium alkyl complex in its monomeric form. Because single component catalysts present possibilities for control of rates, stereochemistry, molecular weights, and molecular weight distributions that can be achieved by the

PAGE 34

34 single catalytic species in pure form, the development of such single component catalysts presents the potential for improved polymers and polymerization processes of ethylene. 1.3 Polymerization of Alkynes Like the polymerization of alkenes, the polym erization of alkynes (acetylene and its analogues ( Figure 1 6 )), which provides polymers having conjugated carbon carbon double bonds, has been studied at length. 2,68 70 However, unlike the polymerization of alkenes the polymerization of alkynes does not take place on an industrial scale because few alkyne polymerization catalysts exist, and those that do fall short of their alkene polymerization counterparts, both in terms of activity and turnover number (TON). Ne vertheless, polymers of acetylene and its derivatives are of great interest both from a basic research and practical application because polyacetylenes (PA) and conjugating polymers. The carbon carbon alter nating double bond in the main chain of these polymers can provide the polymer with unique properties including electrical conductivity, nonlinear optical properties, magnetic properties, gas permeability, and photo and electroluminescent properties. 68 None of these properties are accessible with corresponding vinyl polymers. In the early study of polyacetylene and substit uted polyacetylenes, early transition metal catalysts were found to be most effective, in particular metal halides such as MoCl 5 WCl 6 TaCl 5, and NbCl 5 that are activated by alkylating agents. 71 74 However, in the past decade more late transition metal catalysts have been developed. Now, various transition metals from multiple groups, including Nb Ta, Mo, W, Fe, Ru, Rh, Ir, Pd, are effective to an extent, in the polymerization of substituted acetylene.

PAGE 35

35 One major p roblem with the currently known alkyne polymerization catalysts is the inability of individual catalysts to polymer ize a wide variety of alkyne monomers. Therefore, substrate catalyst matching is necessary because each catalyst possesses limited substrate scope. 70 Table 1 1 adapted from Tang et al. shows a substrate catalyst matching map. As shown, typically, functionalized 1 phenylacetylenes are polymerized only by Rh based catalysts, although non functionalized phenylacetylen e can be polymerized by a wide variety of catalysts. However, Rh based catalysts are typically ineffective at polymerizing disubstituted acetylenes because disubstituted acetylenes are sterically more crowded than their monosubstituted counterparts. As a r esult, a vast majority of the effective disubstituted acetylene polymerization catalysts are group 5 and 6 transition metal catalysts. Thus, the development of catalysts capable of polymerizing a wide variety of acetylenes wi th high activity is important. Despite the wide variety of transition metal catalysts for substituted acetylene polymerization, only two main types of mechanisms for chain growth have been identified: metathesis and insertion. The active species in the metathesis mechanism are typicall y metal alkylidenes 2,75 83 or alkylidynes 84 86 in which an alkyne adds via [2+2] cycloaddition to provide metallocyclobutenes or metallocyclobutadienes, respectively. The ac tive species for the insertion mechanism are typically metal alkyls 2,68 70 or alkylidynes 87 90 in which the alkyne inserts into a metal carbon bond to promote chain growth. In either mechanism, the transition metal catalysts must provide an open coordination site for the coordination and insertion of subsequent monomer units.

PAGE 36

36 Therefore, ligands capable of forcing open or labile metal coordination sites are prerequisites for a lkyne polymerization catalysts. 1.4 Trianionic Pincer Ligands Trianionic pincer ligands are relatively new pincer architecture s capable of supporting reactive metal species. 91 110 They constrain t hree anionic metal ligand bonds to the meridonal plane (Figure 1 7 ). Although they occupy three coordination sites, they can only contribute a maximum of 10 12 electrons, enabling access to coordinatively and electronically unsaturated metal species. Addit ionally, both the NCN 3 and OCO 3 ligands possess a strong M C pincer bond that promotes an open or labile coordination site. 96,99,103 The history of pincer ligated metal complexes began with the synthesis of the fir st pincer PCP ligand, 1,3 bis[(di tert butylphosphino)methyl]benzene, by Shaw in the late 1970s and its subsequent coordination to Rh(III), Ir(III), and group X(II) ions. 111 115 Figure 1 8 depicts the general archit ecture of traditional pincer ligands. These ligands consist of a central anionic aryl ring with ortho, ortho disubstituted heteroatom substituents. The central aryl ring covalently bonds to a metal through a metal bond, rendering stability to the metal complexes. The result is a tridentate and meridonal coordination mode consisting of two metallocycles, which share the M C bond. Pincer complexes act as catalysts for a wide range of important reactions. 116 118 Their utility comes from their modul ar architecture which can modified to supply a variety of useful electronic and steric environments. To date, this ligand framework has been altered in a variety of ways to impart different properties to the metal complexes. Due to their wide usage with va rious transition metals, the pincer ligand has earned the

PAGE 37

37 area. 119 124 Typically, traditional pincer ligands are monoanionic and accommodate late transition metals 125 132 because the soft hard soft donor atoms are better suited for the softer late transition metals (Figure 1 9 A ). Compared to late transition metals, early transition metals have distinct structural and electronic properties. Unlike late transition metals, e arly transition metals favor high oxidation states and high coordination number. T hey are also typically electrophilic and intoler ant to many functional groups. In contras t to traditional pincer ligands, the pincer ligands used herein are trianionic, and they feature three hard donors. Thus, t he hard hard hard trianionic pincer architecture better suits harder early transition metals (Figure 1 9 B and C ). Figure 1 9 displa ys the NCN trianionic pincer ligand ( B ) which can chelate v ia amide arylide amide donors. The analogous OCO trianionic pincer ligand possesses phenoxide arylide phenoxide donors ( C ). The i ntent of my work is to design reactive group VI metal complexes supp orted by the NCN ( 1 ) and OCO ( 2 ) trianionic pincer ligand s capable of catalyzing polymerization reactions. This dissertation details the synthesis of 1) a trianionic NCN pincer supported Cr IV methyl complex and its application as an alkene polymerization p re catalyst and 2) two tetraanionic OCO pincer supported W VI metallocyclopropene comple xes and their application as alkyne polymerization catalysts.

PAGE 38

38 Figure 1 1 Selective isomerization of 6 methyl 6 hepten 2 one Figure 1 2 Transition metal catalyzed isomerization pathways. A Metal hydride addition elimination pathway with a 1,2 hydrogen migration. B 1,3 hydrogen allyl hydride intermediate by a metal complex without a metal hydride bond. Figure 1 3 Examples of classes of homogeneous Cr III based precatalysts/catalysts for ethylene polymerizati on

PAGE 39

39 Figure 1 4 Half sandwich chromium polymerization catalysts Figure 1 5 Two known homogeneous Cr IV alkyl complexes 62 that polymerize ethylen e. Figure 1 6 Polymerization of acetylene and its analogues.

PAGE 40

40 Table 1 1 Table of substrate catalyst matching for polymerization of substituted acetylenes. Substrate Catalyst Mo W Rh Bad Bad Excellent Bad Excellent Good Excellent Good Excellent Excellent Bad Bad Excellent Bad Bad Bad Excellent Bad Bad Excellent Bad Bad Excellent Bad Figure 1 7 The NCN trianionic pincer ligand with amide arylide amide do nors ( 1 ) and the OCO trianionic pincer ligand exists with phenoxide arylide phenoxide donors ( 2 ) Figure 1 8 Traditional pincer l igands

PAGE 41

41 Figure 1 9 Pincer ligand architectures. A. Cla ssic monoanionic pincer ligands (SHS) B C. New trianionic and pincer ligands ( HHH ).

PAGE 42

42 CHAPTER 2 TRIANIONIC NCN 3 PINCER COMPLEXES OF CHROMIUM IN FOUR OXIDATION STATES (CR II CR III CR IV CR V ): PROGRESS TOWARDS AN ETHYLENE POLYMERIZATION CATALYSTS AND DETERMINATION OF THE ACTIVE CATALYST IN SELECTIVE 1 ALKENE TO 2 ALKENE ISOMERIZATION 2.1 Introduction Cr IV alkyls, 62,133 145 including silica supported species, 64 67 are uncommon, as compare d to Cr II and Cr III alkyl complexes, 146 148 due to their greater oxidizing potential of chromium in the 4+ oxidation state and their tendency to decompose via bond homolysis, valence disproportionation, and reductiv e elimination. 149 154 In fact, only one homogenous Cr IV monomethyl and one Cr IV monobutyl complex have been structurally characterized. 133 Despite their instability, silica supported Cr IV complexes have been shown to polymeriz olefins, 63 67 and a theoretical study by Zeigler et al. predicts that the Cr IV alkyl model compounds should be the most highly efficient ethylene polymerization catalysts. 155 Therefore, the development of comparatively difficult to access Cr IV alkyls may be important for promoting ethylene polymerization. Additionally, while a multitude of homogenous Cr II and Cr III complexes, 31 33,36 38,40,56,156 162 which are employed in the polymerizati olefins, 34,35,163,164 exist and serve as informative models of the heterogeneous Phillips 25,26,165 catalyst, few homogenous Cr IV alkyl models exist. Therefore, Cr IV a olefin polymerization, as Cr IV alkyls could act as an informative model of the heterogeneous Phillips 25,26,165 catalyst. One path to develop such a high oxidation state Cr I V alkyl is to stabilize the chromium complex in the 4+ oxidation state with a trianionic pincer ligand. 91 108 This chapter explore s the use of a NCN 3 trianionic ligand 93,96,1 09,110 to stabilize a Cr IV alkyl. Our belief is that the NCN 3 ligand is capable of supporting a reactive 4+ Cr species

PAGE 43

43 because it occupies three coordination sites but only contributes a maximum of 10 12 electrons. Additionally, the NCN 3 ligand possesse s a strong M C pincer bond that olefins. 96 Accomplishing this goal, this chapter details the synthesis, properties, and structural characterization of the Cr IV methyl complex [2,6 i PrNCN]Cr IV Me(THF) ( 6 ; 2,6 i PrNCN = 2,6 bis({[2,6 bis(1 methylethyl)phenyl]azanidyl}methyl)phenyl). 110 This work also exemplifies the versatility of the NCN 3 ligand to support Cr ions in 2+, 3+, 4+, and 5+ oxidation states. 2.2 Results and Discussion 2.2.1 Synthesis of {[2,6 i PrNCN]ZnH 2 } (4). Treating {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) with anhydrous ZnCl 2 pr ovides {[2,6 i PrNCHN]Zn} 2 ( 4 ) in 68% yield (Figure 2 1). Single crystals amenable for X ray diffraction deposit from a concentrated solution of 4 in Et 2 O at 35 C. Figure 2 2 depicts the molecular structure of 4 the caption provides selected bond lengths and angles, and Table A 6 lists X ray refinement data. The single crystal confirms that complex 4 is bimetallic and reveals each Zn ion is two coordinate. Figure 2 3 depicts a truncate d picture highlighting the 16 member metallocycle and the Z shape confo rmation. The Zn(II) ions are two coordinate with nearly a linear geometry between the two ligand molecules (N Zn N avg = 164.86(7) ). Complex 4 is a unique example of a complex with a two coordinate Zn amid o because of their preference t o dimerize. In this case, there are two, two coordinate Zn(II) ions within the same compound. The average bond distance is 1.8116(5) which is much shorter than the sum of the covalent radii (2.13 ) but consistent with other short Zn N bonds which involve considerable Znp to Np bonding in Zn[N(SiMePh 2 ) 2 ] 2 (1.824(14) ), 166 Zn[ N(SiMe 3 )(SiPh 2 t Bu)] 2 (1.853(2) and 1.858(2)

PAGE 44

44 ), 167 Zn[N(SiMe 3 )(Ad)] (1.827(2) and 1.828(14) ), 167 Zn[N(SiMe 3 )( t Bu)] 2 (1.82 ), 168 and Zn[N(SiMe 3 ) 2 ] 2 (1.82 by gas phase electron diffraction). 169 The short Zn N bond distance is unmistakenly due to Znp to Np bonding. A space filling representation of 4 indicates that the Zn ions are well protected by the arene rings and the isopropyl groups (Figure 2 4). Despite this steric protection, 4 reacts instantaneously with H 2 O to form [2,6 i PrNCN]H 3 ( 1 ) and Zn(OH) 2 ; therefore, the Zn ions are easily accessible. A 1 H NMR spectrum of 4 in C 6 D 6 exh ibits broad singlets at 1.24 and 4.23 ppm corresponding to the isopropyl methyl and methylene protons, respectively. A septet at 3.91 ppm corresponds to the methine protons. Overall, the 1 H NMR spectrum is consistent with the formula [2,6 i PrNCHN]Zn but no t with the solid state structural formula. The solid state structure indicates that the methylene protons should be diastereotopic. 2.2.2 Synthesis and Characterization of [2,6 i PrNCN]Cr III (THF) 3 (5), [2,6 i PrNCN]Cr IV Me(THF) (6), and [2,6 i PrNHCN]Cr II (THF) 2 (7 ). Our primary approach to forming Cr based complexes, specifically a Cr Me complex, supported by the NCN 3 ligand was to treat CrMeCl 2 (THF) 3 with {[2,6 i PrNCHN]Zn} 2 ( 4 ). The Zn 2+ salt of the NCN 3 ligand, as opposed to dilithio NCN 3 salt derivative, sho uld better accommodate group VI metals since the Zn 2+ salt is milder and less pr one to reduce a metal substrate. Unfortunately, trea ting 4 with CrMeCl 2 (THF) 3 provides a complex intractable mixture of paramagnetic species and significant quantities of the parent ligand [2,6 i PrNCN]H 3 Following this failed reaction, CrMeCl 2 (THF) 3 was treated directly with the {[2,6 i PrNCHN]Li 2 } 2 ( 3 ). Opportunely, the reaction between CrMeCl 2 (THF) 3 and 3 in Et 2 O at 80 C proceeds smoothly and produces a dark red solution o f three chromium NCN pincer complexes ( Figure 2 5).

PAGE 45

45 The major product of the reaction is the Cr III complex [2,6 i PrNCN]Cr III (THF) 3 ( 5 ). During the reaction disproportionation also provides Cr IV [2,6 i PrNCN] CrMe(THF) ( 6 ) and Cr II [2,6 i PrNCN]Cr(THF) 2 ( 7 ) co mplexes All three complexes 5 6 and 7 can be separated. Pentane insoluble Cr III and LiCl is separated from pentane soluble Cr IV /Cr II by filtration. Pur ification of analytically pure [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) requires titration with pentane and the di ssolving in benzene and filtration to remove the LiCl. Cooling a pentane solution of the Cr IV /Cr II ( 6 / 7 ) mixture to 35 C results in the precipitation of Cr IV complex 6 in 10% yield, which can be dissolved in minimal diethyl ether and cooled to 35C to f orm dark purple single crystals. Repeated (3x) precipitation of 6 from the Cr IV /Cr II ( 6 / 7 ) mixture results in a supernatant containing mostly the Cr II complex 7 in 12% yield, though some 6 and free ligand always remain. Interestingly, the reaction solvent strongly influences the outcome of the reaction between CrMeCl 2 (THF) 3 and 3 For example, conducting the reaction in THF completely suppresses disproportionation and provides the Cr III complex 5 exclusively (Figure 2 6). The Cr III complexes produced eith er in Et 2 O or THF exhibit identical paramagnetic 1 H NMR spectral signatures in C 6 D 6. Broad resonances appear at 5.84 ( 1/2 = 270 Hz), 1.95 ( 1/2 = 420 Hz), and 5.01 ( 1/2 = 390 Hz) ppm although interpretation of the spectrum does not permit structural assignment due to paramagnetic broadening. No resonances are detectable in the 13 C{ 1 H} NMR. The Evans method 170 was used to determine the magnetic moment of the Cr ion. The Evans method provides an experimentally determined magnetic moment of 3.99 B which is consistent with the theoretical value of 3.87 B for a d 3 Cr III ion. This establishe s 5 as a

PAGE 46

46 Cr III complex. Although no crystal structure of 5 was attained despite repeated attempts, combustion analysis of a sample of 5 matches an empirical fo rmula in which three THF ligands are coordinated to the metal center. The analogous OCO 3 trianionic pincer complex [ t BuOCO]Cr III (THF) 3 similarly contains three coordinated THF ligands. 103 This OCO 3 complex possesses a distorted octahedral Cr III metal center; therefore, based on this structural template, complex 5 is assigned an octahedral Cr III metal center. To confirm that that pincer ligand is bound in the tridentate trianionic form, a solution of 5 in C 6 D 6 was quenched with D 2 O. This provides the deuterated free ligand [2,6 i PrNCN]D 3 If the aryl pincer backbone had not been activated the product of this t est would have been [2,6 i PrNCHN]D 2 However, no C ipso H proton of the parent protio ligand [2,6 i PrNCN]H 3 appears at its conspicuous location of 7.57 ppm in the 1 H NMR. Therefore, the aryl backbone is in fact activated and the ligand is bound in the trid entate trianionic form. As mentioned, during the reaction between CrMeCl 2 (THF) 3 and 3 disproportionation also provides a Cr IV ( 6 ) and Cr II ( 7 ). Characterization of the Cr IV complex 6 includes a 1 H NMR spectrum, combustion analysis, and X ray diffraction data. The 1 H NMR spectrum exhibits paramagnetically broadened spectral signatures not suitable for structural assignment. Specifically, broad resonances appear at 25.53 ( 1/2 = 360 Hz), 10.33 ( 1/2 = 90 Hz), 4.23 ( 1/2 = 300 Hz), 0.75 ( 1/ 2 = 300 Hz), and 7.23 ( 1/2 = 165 Hz) ppm. The Evans method 170 provides a magnetic moment of 2.68 B which is consistent with the theoretical value of 2.83 B for a d 2 Cr IV ion. Combustion analysis and X ray diffraction support an empirical formula that include s one THF ligand. Single crystals amenable for X ray diffraction deposit from a concentrated

PAGE 47

47 solution of 6 in Et 2 O at 35 C. Figure 2 7 depicts the molecular structure of 6 the caption provides selected bond lengths and angles, and Table A 11 lists X ray refinement data. The crystal structure shows that complex 6 is C s symmetric and contains a Cr IV ion in a distorted square pyramidal geometry. The NCN ligand exists in its trianionic form with the aryl backbone attached to the Cr IV metal center. The ligand occupies three of the basal sites with a THF molecule residing in the fourth. The methyl gr oup resides in the apical position. Much of the distortion arises from the NCN 3 pincer arms, which cannot span the trans position; instead, the N1 Cr1 N2 angle is 152 The Cr O THF bond length [2.1878(15) ] is elongated due to the strong trans influence of the Cr C pincer bond of the pincer ligand. The related Cr O THF bond lengths in the OCO 3 trianionic Cr III complex [ t BuOCO]Cr III (THF) 3 and Cr V complex [ t BuOCO]Cr V (O)(THF) are 2.1938(18) and 2.1781(17) respectively. Aside from possible steric influence of the different ligands, the Cr O bond lengths vary according to the ionic radius of the Cr ion (Cr III > Cr IV > Cr V ). In both the aforementioned OCO 3 trianionic Cr pincer complexes, the THF is labile. Therefore, complex 6 should exhibit similar substitu tion chemistry. Consistent with the few crystallographically characterized Cr IV complexes that possess a Cr C(sp 3 ) bond, the Cr1 Cr33 bond distance is equal to 2.057(2) In [Cr IV (N 3 N)Me] and [Cr IV (N 3 N)( n Bu)] where N 3 N 3 = ((SiMe 3 NCH 2 CH 2 ) 3 N) 3 the Cr Csp 3 bond lengths are 2.078(2) and 2.074(4) respectively 133 Th e longer Cr C(sp 3 ) bond distance in the N 3 N 3 complexes [0.021(2) ] is likely due to the trans influence of the amine ligand, which is opposite the methyl group. In complex 6 t here are no ligands trans to the N amido bonds indicate

PAGE 48

48 that significant N amido [Cr IV (N 3 N)Me] and [Cr IV (N 3 N)( n Bu)] a Cr N amido average bond length of 1.879 171 In contras t, the Cr N bond lengths in a pincer diimine Cr(III) complex which contain s N imine longer than in 6 by 0.28 172 To balance redox equivalents of Cr IV 6 from the disproportionation during the reaction between CrMeCl 2 (THF) 3 and 3 in Et 2 O, an equal amount of Cr II must form. Indeed, Cr II 7 forms and comprises 12% of the total isolated product. This isolated yield closely parallels the isolated yield of Cr IV 6 (10%). Unfortunately, Cr II 7 could not be fully purified, so an alternate synthesis of 7 was sought. The alternative synthesis involved treating anhydrous CrCl 2 with {[2,6 i PrNCHN] Li 2 } 2 ( 3 ) in THF at 80 C to provide the Cr II complex 7 exclusively (Figure 2 8). The Cr II complexes isolated by the reaction of either the reaction of {[2, 6 i PrNCHN]Li 2 } 2 with CrMeCl 2 (THF) 3 or CrCl 2 exhibit identical paramagnetic ally broadened 1 H NMR spectral signatures in C 6 D 6 Specifically, broad resonances appear at 21.71 ( 1/2 = 330 Hz), 7.96 ( 1/2 = 150 Hz), 6.42 ( 1/2 = 330 Hz), 3.54 ( 1/2 = 685 Hz), a nd 6.88 ( 1/2 = 240 Hz) ppm. The Evans method 170 provides a magnetic moment of 4.42 B which is consistent with the theoretical value of 4.90 B for a d 4 Cr II ion. Although no crystal structure of 7 was attained despite repeated attempts, combustion analysis fits an empirical formula with one NCN ligand in the dianionic form, the Cr ion, and two coordinated THF ligands. Interestingly, a proton is attached to one N atom, as an aniline, not to the aryl backbone. Evidence for this attachment comes from quenching studies. Specifically, quenching a solution of 7 with D 2 O provides a 1 H NMR

PAGE 49

49 spec trum (C 6 D 6 ) in which the distinct resonance at 7.57 ppm for the C ipso H of the protio ligand [2,6 i PrNCN]H 3 is absent. Therefore, the aryl backbone must attach directly to the metal center, and the nitrogen attach as one amide and one aniline attachment. S ubsequent IR spectroscopy studies support this notion as the IR spectrum of 7 contains a weak stretch at 3274 cm 1 corresponding to an NH stretch. 2.2.3 Synthesis and Characterization of [2,6 i PrNCN]Cr V (O)(THF) (8). The Cr III species can be o xidized to a Cr V (O) species by treating 5 with styrene oxide in THF at 35 C. The resulting species is a pentane insoluble Cr V (O) complex [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) ( Figure 2 9 ). 103,135,173 181 Unfortunately, the resonances from complex 8 are paramagnetically broadened beyond interpretation. Nevertheless, the 1 H NMR of the reaction solutions displays spectral signatures consistent with the vinyl protons of styrene at 6.57, 5.63, and 5.09 ppm. Evans method 170 provides a n experimental magnetic moment 1.67 B, consistent with the theoretical magnetic moment for a d 1 Cr V ion of 1.73 B. To further confirm the oxidation state of the Cr, EPR analysis was performed. An EPR spectrum of 2.5 mmol solution of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) displays a strong resonance a t g iso =1.9876 with a 19G line width ( Figure 2 10). The central line corresponds to the allowed ( M s = 1) electron spin transition from the 52 Cr isotope (S = 1/2 I = 0), consistent with a Cr V ion. Lastly, combustion analysis supports the empirical formu la with one THF molecule coordinated to the metal center. Using IR spectroscopy, the Cr V O stretch appears as a strong absorption at 975 cm 1 in the solid state. For comparison, the Cr V O stretch for the analogous OCO 3 complex appears at 988 cm 1 103 Based on the IR stretching frequency, the Cr V O bond in 8 is weaker than Cr V O bond in the analogous OCO 3 complex. However, although

PAGE 50

50 the analogous OCO 3 complex catalytically oxidizes PPh 3 to O=PPh 3 complex 8 does not oxidize PPh 3 at 25 C. 102,103 One plausi ble explanation for this lack of reactivity is due to the difference in stabilities of the Cr V oxidation state. The amido nitrogen on the donors than the oxygen on the OCO ligand. Therefore, the amido nitrogen better stabilize the Cr V oxidation state and reduce its reactivity. 2.2.4 Synthesis of [2,6 i PrNCMeN]H 2 (9) and [2,6 i PrNCBrN]H 2 (10): Attempts to synthesize [2,6 i PrNCN]Cr IV Me(THF) (6) directly. Due to the relative low yield of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) from the reaction be tween CrMeCl 2 (THF) 3 and {[2,6 i PrNCHN]Li 2 } 2 ( 3 ), alternative routes to exclusively synthesize 6 were sought. Two new NCN 3 pincer ligands were synthesized: [2,6 i PrNCMeN]H 2 ( 9 ) (Figure 2 11) and [2,6 i PrNCBrN]H 2 ( 10 ) (Figure 2 12). The thought was to form the dilithio salt derivative of these two ligands than metallate the ligand with CrCl 2 via a salt metathesis to form Cr II species with two anilide attachments and a pincer aryl Me or pincer aryl Br bond. Since complex 6 is a stable Cr IV Me trianionic pince r complex, the Cr II with pincer aryl Me perhaps could undergo oxidative addition to provide 6 exclusively. In the case of the Cr II with the pincer aryl Br, following oxidative addition to provide a Cr IV Br trianionic pincer complex, the bromine could be re placed with a methyl group to yield 6 Unfortunately, a dilithio salt derivative could not be isolated for either ligand ( 9 or 10 ). Attempts to form the dilithio salt derivatives in situ by adding n BuLi then metallating with CrCl 2 were also unsuccessful. T he only route to producing 6 remained via the disproportion reaction between CrMeCl 2 (THF) 3 and {[2,6 i PrNCHN]Li 2 } 2 ( 3 ).

PAGE 51

51 Isomerization of 1 Hexene and 1 Octene Using [2,6 i PrNCN]Cr IV Me(THF) (6). As previously mentioned, the goal of the reaction between CrMeCl 2 (THF) 3 and 3 was to produce a Cr IV Me complex supported by the NCN 3 olefin polymerization. Initially, [2,6 i PrNCN]CrMe(THF) ( 6 ) was screened as a potential olefins (ethylene, 1 hexen e, and 1 octene). However, the discovery that catalytic amounts of 6 selectively isomerized 1 alkenes to internal olefins shifted the focus of the current study, and this selective isomerization was studied with respect to activity and selectivity. Figure 2 13 shows the isomerization of 1 hexene to 2 and 3 hexene. Further investigation into the ability of 6 to polymerize olefin follows in Chapter 3. Homogenous transition metal catalysts for the isomerization of alkenes are synthetically important. 3,182 Specifically, they can be used for selective isomerization applications in organic synthesis. 183 However, catalysts featuring chrom ium are rarely employed as catalysts for this selective isomerization. 184 188 One example of chromium based catalysts for selective isomerization is the in situ generated precatalysts R 3 Cr III (THF) 3 (R = methyl, ethy l, n butyl, decyl), which degrade to form C H containing species. These precatalysts isomerize 1 alkene mainly to cis and trans 2 alkenes within 5 h at 20 C. Isomerization trials were conducted by adding a mixture of [2,6 i PrNCN]Cr IV Me(THF ) ( 6 ) (10 mg, 0 .017 mmol), 1 benzene d 6 (0.5 mL) to a sealable NMR tub e under a nitrogen atmosphere. The reaction mixture was heated in an oil bath thermosta ted at 80 C (1 C) for 72 h. The reaction progress was monitored by 1 H NMR s pectros copy at 48, 60, and 72 h, and t he reaction mixture was analyzed by 1 H NMR spectroscopy to identify and quantify the

PAGE 52

52 organic products. Table 2 1 and 2 2 give the percent conversion and product distribution for 1 hexene and 1 octene isomerization reactions, respectively. All data points were completed in triplicate (average values shown). The catalytic isomerization of 1 hexene and 1 octene using complex 6 to internal olefins occurs nearly quantitatively with 95(1) and 95(2)% conversion, respectively, wit hin 60 h. Interestingly, the isomerization is highly selective for the transformation of 1 alkenes to 2 alkenes. For example, after 48 h, 95% of 1 hexene is converted exclusively to cis / trans 2 hexene, and 88% of 1 octene is converted to cis / trans 2 octe ne. Notably, no cis 4 octene or trans 4 octene is detectable by 1 H NMR spectroscopy even after 72 h. This particular selectivity is unique. While alkene isomerization from terminal to internal olefin is thermodynamically favorable, equilibrium of alkenes t ypically favors structures with the double bond farther from the end of the carbon chain. 10 Following the study of percent conversion and product distribution for the isomerization of 1 hexene and 1 octene by 6 the percent conversion vs. time for both substrates was studied. Figure 2 14 reveals that percent conve rsion vs. time for both 1 hexene and 1 octene follows a sigmoidal curve. The plot shows that an induction period clearly exists at the beginning of the isomerization process. Following this induction period, the reaction accelerates and achieves maximum tu rnover at approximately 16 h. The induction period indicates that 6 does not actively catalyze the isomerization reaction. Instead, 6 is a precatalyst which converts into the active catalyst upon heating. To support this claim, a solution of 6 in C 6 D 6 w as heated at 80 C for 24 h in the absence of any 1 alkene. Then, 1 hexene was added and percent conversion vs. time was monitored ( Figure 2 15). In this case, the plot of percent conversion vs. time shows

PAGE 53

53 no induction period, and the reaction achieves maximu m turnover at the outset. Therefore, the active catalyst must be formed over time by heating 6 The next fitting question to answer therefore, is what is the nature of the active catalyst. Studying the thermolysis of Cr IV 6 in C 6 D 6 by 1 H NMR in the abs ence of substrate elucidates the identity of the active catalyst. Heating a solution of 6 at 85 C in C 6 D 6 produces a complex that exhibits paramagnetically broadened resonances at 21.62, 7.94, 6.45, and 7.01 ppm. At the same time, the paramagnetically br oadened resonances at 25.77, 10 .40, 4.25, and 7.30 ppm of the Cr IV precatalyst 6 disappear. The former resonances are identical to the paramagnetically broadened resonances of the Cr II complex 7 Therefore, the product from the thermolysis of Cr IV is the same Cr II complex 7 that forms from the metallation of {[2,6 i PrNCHN]Li 2 } with either CrMeCl 2 (THF) 3 or CrCl 2 The only difference is that the aniline proton is substituted for a deuterium atom in the thermolysis of Cr IV due to the thermolysis studies being conducted in C 6 D 6 Thus, the active catalyst takes the molecular formula of [2,6 i PrNDCN]Cr II ( THF) 2 ( 7 d ). Figure 2 16 provides the proposed conversion of precatalyst Cr IV 6 to the active catalysts Cr II 7 d Based on this conclusion, the Cr II complex 7 fo rmed exclusively during the metallation of {[2,6 i PrNCHN]Li 2 } with CrCl 2 should catalyze the isomerization of 1 alkenes with no induction period. Indeed, Figure 2 17 shows that no induction period occurs for the isomerization reaction of 1 hexene with 7 A ddition al support for the formation of 7 d specifically that the Cr C pincer bond must be intact, upon heating 6 in benzene comes from quenching studies. Quenching a solution of 7 d with D 2 O provides the deuterated free ligand [2,6 i PrNCN]D 3 as established by 1 H NMR. ESI TOF mass

PAGE 54

54 spectrometry supports the formula [2,6 i PrNCN]DH 2 in which the N D deuterium atoms are exchanged with the protons from methanol, the solvent for the ESI TOF mass spectrometry ( Figure 2 18 ). However, ESI TOF mass spectrometry of a methanol solution of the quenched solution of 7 d with H 2 O supports the formula [2,6 i PrNCN]H 3 in which the N D deuterium atom is exchanged with the protons from methanol (Figure 2 19 ). Based on these results, the Cr C pincer bond must be intact. 2.2.5 Mechanist ic Details for the Thermolysis of [2,6 i PrNCN]Cr IV Me(THF) (6) to [2,6 i PrNDCN]Cr II (THF) 2 (7 d ). A 1 H NMR spectrum of the reaction mixture during the thermolysis of 6 shows the formation of a singlet at 0.16 ppm attributable to CH 4 Additionally, samplin g the headspace of the reaction vessel by GC reveals that CH 4 is present. GC also shows that the reaction solution contains deuterated biphenyl (C 6 D 5 ) 2 ( Figure 2 20 ). Since Cr R complexes are known to decompose via bond homolysis; one plausible mechanism m ay involve the homolytic cleavage of the Cr IV Me bond to form radical intermediates. To test this hypothesis, 2,2,6,6 tetra methylpiperidin 1 yl)oxyl (TEMPO) was added as a radical during the thermolysis of 6 1 H NMR shows the formation of TEMPO Me, indica ting that a CH 3 radical is in fact an intermediate. Therefore, the thermolysis reaction likely occurs through a radical mechanism ( Figure 2 21 and 2 22 ). Based on the available evidence, the Cr IV Me bond homolytically cleaves to produce a Cr III intermedia te and a methyl radical. The methyl radical abstracts a hydrogen atom to from CH 4 The Cr III abstracts a deuterium atom from C 6 D 6 to form Cr IV D intermediate and a deuterated phenyl radical. To test the capacity of the Cr III intermediate to abstract a deut erium atom from C 6 D 6 authentic Cr III ( 5 ) was heated in C 6 D 6 at 85 C. As determined by GC, the product mixture does contain (C 6 D 5 ) 2

PAGE 55

55 Therefore, Cr III can abstract a deuterium atom. The Cr IV D species reductively eliminates to provide 7 d and the deuterat ed phenyl radical adds to C 6 D 6 with concomitant loss of a deuterium atom to from (C 6 D 5 ) 2. 189 2.3 Conclusions The NCN pincer ligand is capable of supporting electronically deficient chromium ions in high oxidation states and low d electron counts. For example, treating CrMeCl 2 (THF) 3 with {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in Et 2 O results in chromium complexes in the Cr II ( 7 ), Cr III ( 5 ), and Cr IV ( 6 ) oxidation states. Subsequent oxidation of the Cr III ( 5 ) complex with styrene oxide yields the Cr V trianionic pincer oxo complex ( 8 ). This ability to stabilize electronic ally deficient chromium ions stems from the combination of strong donation from the two anilides. For the Cr V oxo species ( 8 ), the NCN trianionic pincer ligand stabilizes the Cr V oxidation state to such an extent th at 8 does not perform an O atom transfer even to PPh 3. This lack of reactivity is in contrast with the reactivity of the analogous OCO 3 trianionic pincer complex [ t BuOCO]Cr V (O)(THF), which readily oxidizes PPh 3. As long as no insurmountable kinetic barrie r exists for the O atom transfer with 8 the NCN 3 pincer ligand must be more strongly donating than the OCO 3 pincer ligands. This stronger donating ability comes from the donors than the oxygen on the OCO ligand. Therefore, the amido nitrogen better stabilize the Cr V oxidation state and reduce its reactivity. The major product of the reaction between CrMeCl 2 (THF) 3 an d {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in Et 2 O is the Cr III complex 5 which can also be synthesized exclusively by running the reaction in THF rather than Et 2 O. The mino r disproportionation products are a Cr IV ( 6 ) and Cr II ( 7 ) complex. The Cr IV complex 6 is a

PAGE 56

56 rare exa mple of a stable chromium(IV) monoalkyl. The short Cr N amido bond lengths 3 pincer ligand to stabilize the Cr IV oxidation states. The Cr II complex contains the pincer ligand as a dianion, in which the backbone attaches directly to the metal center and one arm of the ligand binds as an aniline. Insight into why the observed Cr II species exhibits that unexpected conformation comes from thermolysis of the Cr IV complex in C 6 D 6. The products (CH 4 and (C 6 D 5 ) 2 ) from the thermolysis of 6 indicate that the unstabl e Cr IV deuteride [2,6 i PrNCN]Cr IV (D)(THF) 2 forms as an intermediate following homolytic cleavage of the Cr IV Me bond and deuterium abstraction. Subsequent N D reductive elimination provides Cr II ( 7 d ). Since both complexes 7 and 7 d form from salt metathes is between CrCl 2 and {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) and thermolysis, respectively, both reactions share a common intermediate. Figure 2 23 depicts the proposed pathway for the formation of 7 from salt metallation and 7 d from thermolysis of 6 Upon metallation of {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) with CrCl 2 the amido linkages likely attach first to eliminate LiCl, forming intermediate A Then the pincer aryl C H bond oxidatively adds (OA) provide a Cr IV hydride ( B ). The Cr IV oxidation states in B must be unstable relative to Cr II but rather than reductively eliminating to form an aryl C H bond, N H reductive elimination provides 7 The transformation of 6 to 7 plays a significant role during the selective isomerization of 1 alkenes to 2 alkenes. Using complex 6 for the i somerization reactions at 85 C produces an induction period. During this induction period, 6 thermally converts to 7 Preheating complex 6 to form 7 in situ followed by addition of 1 alkene substrates, results in the immediate onset of isomerization. Addi tionally, employing authentic 7

PAGE 57

57 provides a percent conversion profile identical with that of the in situ catalysis. The high selectively of isomerization reactions (95:5, 48 h, 1 hexene; 88:12, 48 h, 1 octene) is kinetically controlled, as prolonged heatin g (2 weeks) results in the thermodynamically expected ratios. Overall, this work shows that the NCN 3 pincer ligand can support chromium in high oxidation states, including Cr IV While the Cr IV Me complex exhibits stability below 85 C the trianionic Cr IV hydride complexes are not stable. Thus, any catalytic application of the Cr IV Me that results in the formation of a Cr IV hydride will result in rapid reductive elimination. 2.4 Experimental Section 2.4.1 General Considerations Unless specified otherwise, all manipulations were performed under an inert atmosphe re using glove box techniques. Tetrahydrofuran (THF), pentane, diethyl ether (Et 2 O), toluene and benzene (C 6 H 6 ) were dried using a GlassContour drying column. C 6 D 6 (Cambridge Isotopes) was dried over sodium benzophenone ketyl, distilled or vacuum transferred and sto red over 4 molecular sieves. Anhydrous ZnCl 2 CrCl 2 1 hexene, 1 octene, styrene oxide and 2,2,6,6 tetramethylpiperidine (TEMPO) were purchased from Sigm a Aldrich and used as receive d. C rMeCl 2 (THF) 3 190 [2,6 i PrNCN]H 3 191 and {[2,6 i PrNCHN]Li 2 } 2 191 were prepared according to literature procedures. 2.4.2 Analytical Techniques 2.4.2.1 NMR t echniques: NMR spectra were obtained on Varian Gemini 300 MHz, Varian VXR 300 MHz, Varian Mercury 300 MHz, Varian Mercury Broad Band 300 MHz, Varian INOVA 500

PAGE 58

58 MHz, or Varia n INOVA2 500 MHz spectrometers. (ppm). For 1 H and 13 C NMR spectra, the residual solvent peak was referenced as an internal reference. 2.4.2.2 IR techniques : Infrared spectra were obtained on a Thermo scientific Nicolet 6700 FT IR. Spectra of solids were measur ed as KBr discs. 2.4.2.3 UV Vis techniques : UV visible spectra were recorded on a Cary 50 with scan software version 3.00(182). 2.4.2.4 GC techniques : Gas chromatography was performed on a Varian CP 3800 gas chromatograph using an intermediate polarity column. 2.4.2.5 MS tech niques : Mass spectrometry was performed at the in house facility of the Department of Chemistry at the University of Florida. Accurate mass was determined by the electrospray ionization time of flight mass spectrometric (ESI TOF) method in methanol. 2.4.2.6 EPR techniques : EPR measurements were conducted using a Bruker Elexsys 500 Spectrometer at the X band microwa ve frequency ~9.4 GHz at 20 K. The microwave frequency was measured with a built in digital counter and the magnetic field was calibrated using 2,2 dip henyl 1 pic rylhydrazyl (DPPH; g = 2.0037). The temperature was controlled using an Oxford Instruments cryosta t, to accuracy within 0.1 K. Modulation amplitude and microwave power were optimized for high signal to noise ratio and narrow peaks

PAGE 59

59 2.4.2.7 Elemental analysis: Combustion analyses were performed at Complete Analysis Laboratory Inc., Parsippany, New Jersey. 2.4.3 Synthesis of {[2,6 i PrNCN]ZnH 2 } (4). A solution of {2,6 i PrNCN]Li 2 H} 2 ( 3 ) (3.015g, 6.434 mmol) in diethyl ether was added to a solution of anhydrous ZnCl 2 (0.877g, 6.434 mmol) in diethy l ether at 35C with stirring. The reaction was warmed to room te mperature and stirred for 1 h. The suspension was filtered to collect a white precipitate which was dried in vacuo to remove all volatiles. The precipita te was redissolved in chloroform. The resulting solution was filtered, reduced under vacuum, and added to pentane with stirring to precipitate out the product. The final product was obtained by decanting off the remaining solution and drying in vacuo. Yi e ld 2.276 g (2.188 mmol, 68%). X ray quality crystals were obtained by slow evaporation from hot benzene solution. 1 H NMR (300 MHz, C 6 D 6 H ), 7.46 (t, 1H, J= 7.5Hz, Ar H ), 7.28 (s, 1H, Ar H ), 7.20 (d, 4H, J=1.5 Hz, Ar H ), 7.15 (t, 2H, J=7.5 Hz, Ar H), 4.23 (s, 4H, Ar C H 2 N), 3.91 (sept, J = 6Hz, 4H, C H (CH 3 ) 2 ), 1.25 (d, J = 6Hz, 24H, CH(C H 3 ) 2 ). 13 C { 1 H} NMR ( 75.36 Hz, C 6 D 6 (s, C aromatic), 131.18 (s, C aromatic), 129.04 (s, C aromatic), 125.90 (s, C aromatic), 125.30 (s, C aromatic), 124.36 (s, C aromatic), 61.37 (s, (s, Ar C H 2 N), 28.33 (s, C H(CH 3 ) 2 ), 25.21 (s, CH( C H 3 ) 2 ). Anal. Calcd for C 64 H 84 N 4 Zn 2 : C, 73.90; H, 8.14; N, 5.39. Found: C, 73.65; H, 8.14; N, 5.39. 2.4.4 Synthesis of [2,6 i PrNCN]Cr III (THF) 3 (5). CrMeCl 2 (THF) 3 (1.000 g, 2.84 mmol) was added to a solution of {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) (1.333 g, 1.42 mmol) in tetrahydrofuran (50 mL) with stirring at 80 C.

PAGE 60

60 The reaction was warmed to room temperature and stirred for 1 h and then all vo latiles were removed in vacuo. Nonvolatile products were dissolved in pentane (50 mL) and filtered to collect an orange solid which was evaporated in vacuo to remove all volatiles. The solid was redissolved in benzene (25mL) and the solution was filtered, reduced under vacuum, and added to a stirring solution of pentane (50 mL) to precipitate 5 as a black crystal line solid. Yield (1.291 g, 63.0%). 1 H NMR (300 MHz, C 6 D 6 (bs, 1/2 = 270 Hz), 1.95 (br s, 1/2 = 420 Hz), 5.01 (bs, 1/2 = 390 Hz). eff B Anal. Calcd. for C 44 H 62 CrN 2 O 3 : C, 73.50; H, 8. 69; N, 3.90. Found: C, 73.39; H, 8.51; N, 4.02 2.4.5 Synthesis of [2,6 i PrNCN]Cr IV Me(THF) (6). CrMeCl 2 (THF) 3 (1.000 g, 2.84 mmol) was added to a solution of {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) (1.333 g, 1.42 mmol) in diethyl ether (50 mL) with stirring at 80 C. The rea ction was warmed to ambient temperature and stirred for 1 h and then the solution was filtered and the filtrate was evaporated in vacuo to produce a dark solid. Pentane was added (50 mL) and the resulting slurry was filtered and the filtrate again was evap orated in vacuo to remove volatiles. The resulting purple red oil was dissolved in minimal pentane and cooled to 35 C to yield a purple precipitate. The product was isolated and purified by filtering the solution a nd washing with cold pentanes. X ray qua lity single crystals were obtained by dissolving 6 in minimal diethyl ether and cooling to 35 C. Yield (185 mg, 10%). 1 H NMR (300 MHz, C 6 D 6 1/2 = 360 Hz), 10.33 (bs, 1/2 = 90 Hz), 4.23 (bs, 1/2 = 300 Hz), 0.75 (bs, 1/2 = 300 Hz), 7.23 (bs, 1/2 = 165 Hz). eff B Anal. Calcd. for C 37 H 52 CrN 2 O: C, 74.96; H, 8.84; N, 4.73. Found: C, 74.92; H, 8.96; N, 4.72.

PAGE 61

61 2.4.6 Syn thesis of [2,6 i PrNHCN]Cr II (THF) 2 (7). Anhydrous CrCl 2 (524 mg, 4.268 mmol) was added to a solution of {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) (2.00 g, 2.13 mmol) in THF (50 mL) with stirring at 80 C. The reaction was warmed to ambient temperature and stirred for 1 h and then all volatiles were remove d in vacuo to provide a solid. The solid was dissolved in pentane (50 mL) and the solution was filtered and the fil trate was evaporated in vacuo. The resulting purple red oil was dissolved in minimal ether and cooled to 3 5 C to yield 7 as a purple precipitate. Yield (287 mg, 10%). 1 H NMR (300 MHz, C 6 D 6 1/2 = 330 Hz), 7.96 (bs, 1/2 = 150 Hz), 6.42 (bs, 1/2 = 330 Hz), 3.54 (bs, 1/2 = 685 Hz), 6.88 (bs, 1/2 = 240 Hz). eff B Anal. Calcd. f or C 40 H 58 CrN 2 O 2 : C, 73.81; H, 8.98; N, 4.30. Found: C, 73.72; H, 8.85; N, 4.27. 2.4.7 Synthesis of [2,6 i PrNCN]Cr V (O)(THF) (8). The complex [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) (500 mg, 0.693 mmol) was treated with styrene oxide with stirring at 35 C. The reaction was warmed to ambient temperature and stirred for 30 min and then all vo latiles were removed in vacuo. Nonvolatile products were dissolved in pentane (10 mL) and filtered to collect the product as a black solid. Yield (407 mg, 99%). eff B Anal. Calcd. for C 36 H 49 CrN 2 O 2 : C, 72.82; H, 8.32; N, 4.72. Found: C, 72.76; H, 8.41; N, 4.58. 2.4.8 Synthesis of 1,3 Bis(2',6' dimethylphenylaminomethyl)toluene (9). n Butyl lithium (2.5 M solution in hexane, 4.35 mmol) was added to 2,6 diisopro pyl aniline (0.814 mL, 4.32 mmol ) in THF at 0C with stirring. To this mixture, a solution of 1,3 bis(bromomethyl)toluene 191 194 (600 mg, 2.16 mmol) in THF was added dropwise. The reaction was warmed to room tem pera ture and stirred for 48 h. Water (50 mL) was added and the mixture was extracted w ith diethyl ether (2 x 50 mL). The

PAGE 62

62 ethereal layer was dried with magnesium sulfate and volatiles were removed in vacuo yielding an orange oil. Crystalline product was attaine d by dissolving in minimal hot hexane and cooling to 0C. Yield (567 mg, 55.9%). 1 H NMR (500 MHz, C 6 D 6 7.51 (d, 2H, Ar H ), 7.07 (t, 1H, Ar H ), 4.09 (s, 4H, Ar C H 2 N), 3.38 (sept, 4H, C H (CH 3 ) 2 ), 3.09 (s, 2H, Ar C H 2 N H ), 2.35 (s, 3H, Ar C H 3 ), 1.22 (d 24H, CH(C H 3 ) 2 ). 13 C { 1 H} NMR (125.6 Hz, C 6 D 6 aromatic), 135.08 (s, C aromatic), 128.31(s, C aromatic), 126.95 (s, C aromatic), 125.07 (s, C aromatic), 124.38 (s, C aromatic), 55.18 ( s, Ar C H 2 N), 28.55 (s, C H(CH 3 ) 2 ), 24.82 (s, CH( C H 3 ) 2 ), 14.67 (s, Ar C H 3 ). Anal. Calcd for C 33 H 46 N 2 : C, 84.20; H, 9.85; N, 5.95. Found: C, 84.564 ; H, 10.233 ; N, 5.89. 2.4.9 Synthesis of 1,3 Bis(2',6' dimethylphenylaminomethyl) 2 bromobenzene (10). n Butyl lithi um (2.5 M solution in hexane, 29.11 mmol) was added to 2,6 diisopropyl aniline (5.46 mL, 28.96 mmo l) in THF at 0C with stirring. To this mixture, a solution of 1,3 bis(bromomethyl) 2 bromobenzene (4.965 g, 14.48 mmol) in THF was added dropwise The reacti on was warmed to room temperature and stirred for 48 h. Water (50 mL) was added and the mixture was extracted w ith diethyl ether (2 x 50 mL). The ethereal layer was dried with magnesium sulfate and volatiles were removed in vacuo yielding an orange oil. C rystalline product was attained by dissolving in minimal hot hexane and cooling to 0C. Yield (5.83 g, 75.1%). 1 H NMR (500 MHz, C 6 D 6 (ppm): 7.42 (d, 2H, Ar H ), 7.20 (s, 2H, Ar H ), 7.02 (t, 1H, Ar H 2 ), 4.28 (s, 4H, Ar CH 2 N), 3.46 (s, 2H, Ar C H 2 N H ), 3.39 (sept, 4H, C H (CH 3 ) 2 ), 1.22 (d, 24H, CH(C H 3 ) 2 ). 13 C { 1 H} NMR (125.6 Hz, C 6 D 6 140.91 (s, C aromatic), 129.20 (s, C aromatic), 128.09 (s, C aromatic), 125.69 (s, C aromatic),

PAGE 63

63 125.18 (s, C aromatic), 124.40 (s, C aromatic), 56.96 (s, Ar C H 2 N), 28.45(s, C H(CH 3 ) 2 ), 24.81 (s, CH( C H 3 ) 2 ). Anal. Calcd for C 32 H 43 N 2 Br: C, 71.76; H, 8.09; N, 5.23. Found: C, 72.083; H, 8.286; N, 5.136. 2.4.10 Isomerization of 1 Hexene and 1 Octene using [2,6 i PrNCN]Cr IV Me(THF) (6). A mixture of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (10 mg, 0.017 mmol), 1 hexene (20.5 d 6 (0.5 mL) were added to a sealable NMR tub e under a nitrogen atmosphere. The reaction mixture was heated in an oil bath thermosta ted at 80 C (1 C) for 72 h. The reaction progress was monitored by 1 H NMR spe ctroscopy at 48, 60, and 72 h. The reaction mixture was analyzed by 1 H NMR spectroscopy to identify and quantify the organic products. Kinetic Measurements : For kinetic measurements the reaction was setup using the method above an d the reaction progress was monitored by 1 H NMR spectroscopy at 4, 8, 12, 16, 20, 24, 28, 32, and 36 h. Conversion % of 1 hexene to 2 hexene was determined by 1 H NMR spectroscopy. The above procedure was adopted for the isomerization of 1 octene. Preheatin g (24 h, 85 C): The sample setup was the same as above with the exception that alkene subs trate was not added initially. The sealable reaction mixture was heated in an oil bath thermosta ted at 85 C (1 C) for 24 h. After heating, 1 2 mmol) was added to the NMR tube under a nitrogen atmosphere and returned to the oil bath. The reaction progress was monitored by 1 H NMR spectroscopy at 2, 4, 8, 12, 16, 20, 24, 28, 32, 36 h. The above procedures were adopted for the isomerization of 1 oc tene.

PAGE 64

64 2.4.11 TEMPO Procedures. A mixture of 2,2,6,6 tetramethylpiperidine (TEMPO) (0.017 mmol), [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (10 mg, 0.017 mmol), and benzene d 6 (0.5 mL) were added to a sealable NMR tub e under a nitrogen atmosphere. The reaction mixture was heat ed in an oil bath thermosta ted at 85 C (1 C) for 24 h. The reaction progress was monitored by 1 H NMR sp ectroscopy at 4, 12, and 24 h. The reaction mixture was analyzed by gas chromatography to identify and quantify the organic products using an internal st andard (hexamethyldisiloxane). The above procedure was adopted for reaction involving 10 equiv of TEMPO. Figure 2 1. Formation of {[2,6 i PrNCHN]Zn} 2 ( 4 ).

PAGE 65

65 Figure 2 2. Ortep drawings of the molecular structure of { [2,6 i PrNCHN]Zn} 2 ( 4 ) with ellipsoids drawn at the 50% probability level and hydrogen removed for clarity. Selected bond lengths () and angles (): Zn1a N1a, 1.8100(15); Zn1a N3a, 1.8119(15); Zn2a N2a, 1.8161(15); Zn2a N4a, 1.8141(15); N1a Zn1a N3a, 164.6 5(7); N4a Zn2a N2a, 166.64(7).

PAGE 66

66 Figure 2 3. Truncated view of 4 highlighting the two coordinate Zn ions and the 16 membered Z shaped metallocy c le. Figure 2 4. Space filling drawing of the structure of {[2,6 i PrNCHN]Zn} 2 ( 4 ).

PAGE 67

67 Figure 2 5. Three trianionic NCN 3 pi ncer ligand chromium complexes ( 5 6 and 7 ) form by treating CrMeCl 2 (THF) 3 with {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in diethyl ether at 80 C Figure 2 6. Exclusive formation of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) using THF as the solvent

PAGE 68

68 Figure 2 7. Molecular structure of [2,6 i PrNCN]Cr IV Me( THF) ( 5 ) with ellipsoids presented at the 50% probability level and hydro gen atoms removed for clarity. The selected bond lengths () and angles (deg): Cr(1) N(1) 1.9048(19), Cr(1) N(2) 1.8870(19), Cr(1) C(13) 1.953(2), Cr(1) O(1) 2.1878(15), N(2) Cr(1) N(1) 152.00(8), C(13) Cr(1) O(1) 165.78(7), C(13) Cr(1) C(33) 96.34(9), C(33) Cr(1) O(1) 97.85(8). Figure 2 8. Treating anhydrous CrCl 2 with {[2,6 i PrNCHN]Li 2 } 2 ( 3 ) in THF at 80 C provides [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ).

PAGE 69

69 Figure 2 9. Treating 5 with styrene oxide in THF at 35 C provides the Cr V (O) complex [2,6 i PrNCN]Cr V (O)(THF) ( 8 ). Figure 2 10. EPR spectrum of [2,6 i PrNCN]C r V (O)(THF) ( 8 ) (2.5 mM solution, toluene) at T = 20 K.

PAGE 70

70 Figure 2 11. Synthesis of [2,6 i PrNCMeN]H 2 ( 9 ). Figure 2 12. Synthesis of [2,6 i PrNC Br N]H 2 ( 10 ).

PAGE 71

71 Figure 2 13. Transient 1 H NMR spectra obtained in benzene d 6 of [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ) in solution with 1 hexene; progress of the isomerization Table 2 1. Isomerization of 1 hexene using 6 as the precatalyst. [a] Reaction Time (h) Conversion (%) [b] trans 2 hexene/ cis 2 hexene (%) [b] trans 3 hexene/ cis 3 hexene (%) [b] 48 90 (5) 95 (2) 5 (2) 60 95 (1) 92 (2) 8 (2) 72 96 (0) 87 (3) 13 (3) [a] Isomerization was carried out with [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (10 mg, 0.017 mmol), C 6 D 6 (0.5 mL), and 1 C. [b] Percent conversion and product composition measured by 1 H NMR (500 MHz).

PAGE 72

72 Table 2 2. Isomerization of 1 octene using 6 as the precatalyst. [a] Reaction Time (h) Conversion (%) [b] trans 2 octene/ cis 2 octene (%) [b] trans 3 octene/ cis 3 octene (%) [b] 48 90 (3) 88 (2) 12 (2) 60 95 (2) 86 (3) 14 (3) 72 97 (0) 82 (3) 18 (3) [a] Isomerization was carried out with [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (10 mg, 0.017 mmol ), C 6 D 6 (0 .5 mL), and 1 C. [b] Percent conversion and product composition measured by 1 H NMR (500 MHz). Figure 2 14. Catalytic % conversion of 1 hexene and 1 octene versus time with 6 as the precatalyst in C 6 D 6 at 85 C.

PAGE 73

73 Figure 2 15. Catalytic % conversion of 1 hexene upon preheatin g 6 to 85 C for 24 h, followed by substrate addition. Figure 2 16. Proposed conversion of precatalyst Cr IV ( 6 ) to the active catalyst C r II ( 7 d ).

PAGE 74

74 Figure 2 17. Catalytic % conversion of 1 hexene by 7 in C 6 D 6 at 85 C. Figure 2 18. ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with D 2 O.

PAGE 75

75 Figure 2 19 ESI TOF mass spectra of [2,6 i PrNCN]C r IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with H 2 O. Figure 2 20 Gas chromatographic spectrum of the reaction products in solution ( ) after heating [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) for 48 h at 85C.

PAGE 76

76 Figure 2 2 1 Proposed mechanism for thermolysis of 6 to form CH 4 and (C 6 D 5 ) 2 Figure 2 22 Proposed mechanism for thermolysis of 6 in the presence of TEMPO.

PAGE 77

77 Figure 2 23 Formation of 7 ( 7 d ) via salt metathesis or thermolysis of 6 featuring a common intermediate.

PAGE 78

78 CHAPTER 3 A NEUTRAL TRIANIONIC PINCER [NCN]CR IV ME COMPLEX AS A HIGHLY ACTIVE ETHYLENE POLYMERIZATION PRECATALYST 3.1 Introduction The aforementioned synthesized, characterized, and isolated [NCN]Cr IV Me complex ( 6 ) is of particular interest with regards to olefin polymerization, as numerous homogenous chromium complexes featuring an alkyl group bonded to the chromium or a chromium complex capable of accessing such a structure upon activation polymer ize ethylene. Furthermore, these well defined homogenous chromium based catalysts can potentially be used as informative models of the heterogeneous Phillips catalyst, 25,26,165 which is responsible for nearly one th ird of all high density polyethylene currently produced. 163 What is unique about the [NCN]Cr IV Me complex 6 as compared to the majority of homogenous chromium based precatalys ts/catalysts for ethylene polymerization is its 4+ oxidation state. For an overwhelming majority of reports, homogenous chromium based precatalysts/catalysts exist in the 3+ oxidation state. 30 These homogeneous chromium based precatalysts/catalysts include cationic Cr III monoalkyls 31 35 or neutral Cr III monoalkyl complexes, 36 39 Cr III dialkyls, 32,40 43 and Cr III mono 37,44 48 or dichloride species. 32,40,49 58 (Figure 3 1 ) What is similar about the [NCN]Cr IV Me complex 6 to these Cr III based precatalysts/catalysts is its alkyl group bonded to the chr omium metal center. Though the homogeneous chromium systems often require different activators (i.e, methylaluminoxane (MAO), tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 and trialkylaluminum (AlR 3 )), they all share the common structural feature of an alkyl gr oup bonded to chromium or a chromium complex capable of accessing such a structure upon activation. An active species with a chromium alkyl bond is considered a

PAGE 79

79 requirement for ethylene polymerization because the generally accepted mechanism of polymer cha in growth involves the coordination of ethylene to a metal with an alkyl group, followed by migratory insertion of the olefin into the metal carbon bond. In comparison to the multitude of homogenous Cr III precatalysts/catalysts for ethylene polymerizatio n, there are only a few Cr IV models that possess a chromium alkyl bond and polymerize ethylene. In fact, only two homoleptic Cr IV R 4 (R=CH 2 C(CH 3 ) 3 and CH 2 Si(CH 3 ) 3 ) complexes 62 (Figure 3 2 ) and a few silica supported Cr IV alkyls 63 67 are known. The scarcity of applicable Cr IV catalysts is largely due to the greater oxidizing potential of chromium in the 4+ oxidation state. Additionally, Cr IV complexes exhibit a tendency to decom pose via bond homolysis, valence disproportionation, and reductive elimination. 149 154 Nevertheless, theoretical studies predict that cationic Cr IV alkyl model complexes with a d 2 electron count should demonstrate t he highest catalytic activity of various d electron counts. Therefore, the [NCN]Cr IV Me complex 6 may potentially be a highly active e thylene polymerization catalyst and may represent a potential Cr IV alkyl model, which is comparatively difficult to acces s. Along with the required chromium alkyl bond, the [NCN]Cr IV Me complex 6 also possesses a ligand that creates a coordinatively and electronically unsaturated metal center that can easily coordinate ethylene but resists dimerization. The trianionic pince r ligand 91,93 100,102 105,107,108,110,195 constrains three anionic donors in a meridonal plane permitting substrate attack at unhindered vacant coordination sites. While occupying three coordination sites, the ligan d only contributes a maximum of 10 12 electrons leading to an electronically unsaturated complex. With respect to d electron count, the [NCN]Cr IV Me complex 6

PAGE 80

80 electron CpCr III alkyl complex, [Cp*C r(THF) 2 Me]BPh 4 ], 34,35 which polymerizes ethylene. Complex 6 is a 14 electron species, including the bound tetrahydrofuran (THF) (Figure 3 3 ). Additionally, since the [NCN] 3 ligand features a strong M C pincer bond t hat promotes an open or labile trans coordination site, 96,99,103 complex 6 can potentially access an even more electronically unsaturated 12 electron state. Therefore, the Cr IV metal center is highly electrophilic a nd should rapidly bind ethylene. As such, a detailed investigation of the ability of [NCN]Cr IV Me complex 6 to polymerize ethylene with and without activators was pursued. 3.2 Results and Discussion 3.2.1 Determination of Optimal Cocatalyst The Cr IV Me complex 6 wa s tested as a catalyst/precatalyst for ethylene polymerization under various conditions. Table 3 1 summarizes the experimental results of the ethylene polymerization. Initially, ethylene gas (Matheson purity) was introduced into a solution of complex 6 in toluene without cocatalyst in hopes of polymerizing ethylene without cocatalyst. Unfortunately, despite its coordinative and electronic unsaturation, complex 6 shows no activity in the absence of cocatalyst. Therefore, all future attempts made use of a coc atalyst. The first two cocatalysts screened were modified methylaluminoxane (MMAO) and tris(pentafluorophenyl)borane (B(C 6 F 5 ) 3 ). Unfortunately, addition of either cocatalyst did not help yield significant polyethylene. Using MMAO produces polyethylene, but the activity is low (1.8 x 10 4 g PE(molCr) 1 h 1 ). Addition of B(C 6 F 5 ) 3 as a cocatalyst only results in trace amount of polyethylene. The likely reason for the poor polyethylene production when employing these two cocatalysts is due to their high Lewis ac idity and the ability of B(C 6 F 5 ) 3 specifically, to abstract methide ions. 196,197 Ample precedent indicates that the reactions between

PAGE 81

81 B(C 6 F 5 ) 3 and zirconocene dimethyl complexes proceed rapidly to provide cationic alkylzirconocene methyltriarylborate complexes via methide abstraction. 198 201 (Figure 3 4 ) Additionally, methide abstraction occurs upon treatment of Cr III dimethyl complexes with B(C 6 F 5 ) 3 forming cationic chromiu m monomethyl complexes. 32,41,42 Therefore, treatment of complex 6 with B(C 6 F 5 ) 3 likely abstracts the sole methyl group producing a cationi c chromium methyltriarylborate complex {[2,6 i PrNCN]Cr IV }{MeB(C 6 F 5 ) 3 } ( 11 ) (F igure 3 5) To determine whether the methyl group is indeed abstracted, the reaction between complex 6 and 1 equiv. of B( C 6 F 5 ) 3 was monitored by 19 F NMR. Upon treating complex 6 with B(C 6 F 5 ) 3 in C 6 D 6 19 F NMR spectroscopy shows in accordance with literatu re date, the immediate formation of the anion [MeB(C 6 F 5 ) 3 ] by three sets of upfield shifted resonances ( 139.6 ( o F), 154.50 ( p F), 162.76 ( m F)) for the ortho meta and para positions of the aryl rings with respect to the precursor B(C 6 F 5 ) 3 201 205 Attempts were made to isolate the product but were unsuccessful due to decomposition of the product. Since 11 lacks the necessary chromium alkyl bond needed to polymerize ethylene, it is no surprise that only trace qu antities of polyethylene form upon addition of ethylene to a mixture of complex 6 and B(C 6 F 5 ) 3 This too can explain the low activity when MMAO is the activator, as MMAO is highly Lewis acidic. In order to activate complex 6 yet maintain the chromium alk yl moiety, a less Lewis acidic activator was chosen, specifically triisobutylaluminum (TIBA). (Figure 3 6) Opportunely, in the presence of 10 equiv. of TIBA as an activator, complex 6 ( polymerizes ethylene with catalytic activities up to 4.0 x 10 6 g PE(molCr) 1 h 1 Clearly, the nature of the activator has an important influence on activity, and literature precedent supports the observed preference for alkylaluminum activators over

PAGE 82

82 methylaluminoxanes and boranes for neutral Cr III monoalkyl polymeriz ation precatalysts. 37,38 The superior reactivity of 6 while using TIBA as an activator is presumably due to th e lower Lewis acidity of TIBA. Compared to the proficient methyl abstractors, MMAO and B(C 6 F 5 ) 3 TIBA i s unlikely to abstract methide. 197 Thus, TIBA effectively activates complex 6 yet lik ely maintains the integrity of the chromium alkyl bond allowing for polymerization to occur. 3.2.2 Determination of Optimal Reaction Temperature and TIBA:6 Molar Ratio After determination of the optimal cocatalyst, optimal polymerization conditions were obtaine d by varying the reaction temperature and Al:Cr molar ratio. With respect to reaction temperature, reactions were specifically conducted at 25 C, 50 C, 75 C, and 100 C. Catalytic activity increases significantly with an increase in reaction temperature from 25 C to 75 C, but decreases from 75 C to 100 C, indicating that the system becomes unstable at some temperature above 75 C (Table 3 1 entries 7, 8, 9, 10). These findings are not surprising considering that complex 6 was previously shown to exh ibit thermal instability above 85 C. 110 All further polymeriza tion trial runs were conducted at 75 C. Next, the Al:Cr molar ratio was studied by specifically varying the TIBA: 6 6 ). An optimal ratio occurs at 10 equiv. of TIBA: 6 yielding an optimal activity of 4.00 x 10 6 g PE(molCr) 1 h 1 When the TIBA:Cr ratio is less than 5, only small quantities of polyethylene form. Moreover, no pol ymerization occurs when equimolar or 2 equiv. of TIBA are used. Interestingly, further increases in the TIBA:Cr ratio beyond 10 equiv. has a negative effect on catalytic activity (Table 3 1 entries 14, 15 16). Nevertheless, these findings are not overly surprising considering half sandwich chromium(III) chloride complexes exhibit a similar cocatalyst:catalyst relationship. 45,47

PAGE 83

83 The effect of the ratio of TIBA: 6 was probed further by investigating the optimal TIBA 6 ). Figure 3 7 displays the results for polymerization activity (kg PE(molCr) 1 h 1 35 equiv. of TIBA: 6 yielding an optimal activity of 7.02 x 10 6 g PE(molCr) 1 h 1 Polyethylene production increases from a TIBA:Cr ratio of 10 to the optimal TIBA:Cr ratio of 35. (Table 3 1 entries 17, 18, 19, 20). Similar to the aforementioned results u catalyst loading, a further increase in the TIBA:Cr ratio beyond 35 equiv. negatively effects catalytic activity (Table 3 1 entries 21, 22, 23). activity increas es up to an optimal TIBA:Cr ratio; then, catalytic activity decreases above this optimal ratio. However, the optimal ratio is not the same. In fact, the TIBA:Cr ratio of this disparity is likely due to trace amounts of catalyst incompatible water in the system. Since TIB A can act both as a scavenger of water 163,197 and as an activator of complex 6 a certain quantity of TIBA is needed to remove the trace quantities of catalyst incompatible water. Considering the total amount of TIBA rather than the TIBA:Cr ratio, yst loading polymeriz ation studies, a minimum of 20 in minimal polyethylene production. T he remaining TIBA serves to activate complex 6 3.2.3 Polyethylene Characterizat ion All polyethylene samples were characterized by differential scanning calorimetry (DSC), 13 C{ 1 H} NMR, and gel permeation chromatography (GPC). DSC provides the

PAGE 84

84 melting transition temperature and crystallinity (Table 3 1 ). The DSC diagrams show a sharp e ndothermic melting peak in the range of 133 140 C with crystallinity values in the range of 56 75%. These crystallinity values are typical for high density of polyethylene (HDPE). 44,206,207 Spectroscopic analysis v ia 13 C{ 1 H} NMR of the polymer samples in 1,3,5 trichlorobenzene d 3 at 130 C also indicates that the polyethylene is linear with no detectable branching (Figure 3 8) 208 210 GPC in 1,2,4 trichlorobenzene at 150 C p rovides the average molecular weights as well as the polydispersities of the polyethylene samples. Similar to metallocene Cr III catalysts 211,212 as well as half sandwich Cr III catalysts, 44,206,213 the molecular weights of the polyethylene decrease with an increase in polymerization reaction temperature and TIBA: Cr molar ratio. Unfortunately, t he large polydispersities are quite large, indicating that multiple active sites are operable. This precludes an informed evaluation of the catalyst/ligand properties, active catalysts identity, and oxidation state. 3.3 Conclusions Relatively few homogeneous non cyclopentadienyl chromium ethylene polymerization precatalysts/catalysts exist. T he trianionic NCN 3 pincer ligand Cr IV Me complex [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) is a notable addition to this limited list. Even more distinctively, complex 6 is only the third well characterized homogeneous Cr IV complex known to polymerize ethylene. While C r IV precatalysts/catalysts are scarce due to the greater oxidizing potential of chromium in the 4+ oxidation state, the trianionic pincer ligand stabilizes the high oxidation of the chromium metal center and provides for the electronically deficient Cr IV d 2 donation from the pincer donating anilides. The high catalytic activity indicates that complex 6 coordinates ethylene rapidly. This reactivity is presumably due to the lability of the THF

PAGE 85

85 as evidenced by th e long Cr THF bond length of 2.1878(15) 110 Furthermore, the high 162 : 351 g PE(mmolC r) 1 h 1 barr 1 ) is consistent with theoretical studies by Ziegler et al. that indicate Cr IV model complexes should demonstrate the highest catalytic activity of various d electron counts because fewer d electrons open a lower metal based LUMO acceptor orb ital. 52 The choice of activator clearly affects the act ivity of the catalytic system. Using MMAO as an activator only produces marginal quantities of polyethylene, and using B(C 6 F 5 ) 3 as an activator yields no polyethylene. On the other hand, using TIBA results in high polyethylene yield. Based on the relative Lewis acidities of these activators, a less Lewis acidic activator is preferred, as the stronger Lewis acidic activators, MMAO and B(C 6 F 5 ) 3 likely irreversibly deactivate the catalyst via methide abstraction. Since the chromium alkyl moiety is generally n ecessary for olefin polymerization, the appropriate activator for neutral monomethyl metal complexes is essential. Unfortunately, the mechanism by which TIBA activates complex 6 the active catalyst identity, and oxidation state were not possible to attain Attempts to assess the role of TIBA with 6 by adding a stoichiometric quantity did not yield an isolable or identifiable species. Based on the large polydispersities, it is likely that multiple active sites are operable. Three plausible possibilities exi st for how TIBA activates 6 One possibility is that TIBA can simply activate the Cr Me bond towards insertions, while another possibility is that TIBA can replace Me via transmetallation of an isobutyl group. This would enhance the rate of ethylene inser tion as that rate of ethylene insertion into a M Me bond. 214 218 Alternatively, Mu et al., employing the half sandwich precatalysts Cp*Cr[2,4

PAGE 86

86 t Bu 2 6 (CH=NR) C 6 H 2 O]Cl, 44,47 suggest that trialkylaluminum cocatalysts create heterobimetallic bridged Cr Al species that are sensitive to the concentration of AlR 3. Perhaps coincidentally, but rather striking, both 6 and Cp*Cr[2,4 t Bu 2 6 (CH=NR) C 6 H 2 O]Cl require approximately 25 equiv. of AlR 3 to optimize activity. With respect to catalytic performance, complex 6 exhibits superior performance in comparison to previously reported neutral Cr III monoalkyl complexes with no activator or diethylalu minum chloride (Et 2 AlCl) as activator. 36 39 (Table 3 2) Additionally, the catalytic activity of 6 compares closely to previously reported half metallocene type Cr III monochloride complexes activated by trialkylalumi num and approaches the catalytic activities reached by cationic metallocene catalysts of zirconium and titanium. 219,220 (Table 3 4 act ive constrained geometry Cr III dichloride complexes, 32,40,51,54,56 these chromium dichloride catalysts require large excesses of methylaluminoxanes (MAO:Cr = 100 2,000). Therefore, the present system offers the ad vantage of high catalytic activity without need for larges excesses of expensive cocatalysts. 3.4 Experimental Section 3.4.1 General Considerations Unless specified otherwise, all manipulations were performed under an inert atmosphe re using glove box tec hnique s. Tetrahydrofuran (THF), pentane, diethyl ether (Et 2 O), toluene and benzene (C 6 H 6 ) were dried using a GlassContour drying column. C 6 D 6 (Cambridge Isotopes) was dried over sodium benzophenone ketyl, distilled or vacuum transferred and stored over 4 molec ular sieves. CrMeCl 2 (THF) 3 190 [2,6 i PrNCN]H 3 191 {[2,6 i PrNCHN]Li 2 } 2 191 and [2,6 i PrNCN]Cr IV Me(THF) 110 were prepared according to literature procedures. Ethylene (Matheson Purity 99.995%) was purchased

PAGE 87

87 from Matheso n Tri Gas and used as received. Triisobutylaluminum (TIBA) (25 wt. % in toluene) was purchased from Sigma Aldrich and used as received. B(C 6 F 5 ) 3 was purchased from Strem Chemicals and used as received. 3.4.2 Polymerization of Ethylene using [2,6 i PrNCN]Cr IV Me(THF) (6). A 300 mL pressure reactor (Parr Instruments 4560 Series) was charged with 50 mL of toluene and triisobutylalu minum under nitrogen. Mechanical stirring was started, and the reactor was purged with ethylene. The reactor was heated to an internal pre catalyst ( 6 ) in 1 mL of toluene was injected via syringe into the reactor. The reactor was quickly pressurized with 20 bar of ethylene. Ethylene pressure was kept constant during the reaction by replenishing the flow. The reaction was carried out for 15 min after which the reactor was vented and cooled. A known amount of cyclohex ane was injected, and a sample of the liquids was taken and filtered for GC analysis. The polymeric material was collected by filtration, washed with acidified methanol (0.1 M), and dried in vacuo at 80 C for 2 h prior to weighing. The above procedure was adopted for all other polymerization trials. Polyethylene analysis by GPC and DSC was performed at Dow Chemical Inc., Midland, Michigan

PAGE 88

88 Figure 3 1. Examples of classes of homogeneous Cr III based precatalysts/catalysts f or ethylene polymerization Figure 3 2 Two known homogeneous Cr IV alkyl complexes 62 that polymerize ethylene. Figure 3 3. 5 e [Cp*Cr(THF) 2 Me]BPh 4 catalyst 34,35 compared to the neutral 14 e [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) (1; Ar = 2,6 bis(1 methylethyl)phenyl).

PAGE 89

89 Figure 3 4. Reactions between B(C 6 F 5 ) 3 and zirconocene dimethyl complex to provide cationic alkylzirconocene methyltriarylborate complex via methide abstraction. 200,201,221 Figure 3 5. Methyl abstraction by B(C 6 F 5 ) 3 Figure 3 6 Relative acidity ordering of common cocatalyst activators. 222

PAGE 90

90 Table 3 1 Results of ethylene polym erization using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) [a] Cocat. 1 Cocat.: 1 Temp (C) (gPE) Activity (kg/molCr/h) M w [b] x 10 5 M w /M n [b] T m [c] (C) c [d] (%) 1 [e] none 10 N/A 50 0 0 2 [e] none 10 N/A 75 0 0 3 [e] MMAO 10 10 50 0.090 18 4 [e] MMAO 10 500 50 0.088 18 5 [e] FAB 10 1 50 trace 0 6 [e] FAB 10 10 50 trace 0 7 TIBA 5 10 25 0.473 378 5.88 26.6 138.7 58.3 8 TIBA 5 10 50 1.017 814 4.21 32.5 138.3 61.4 9 TIBA 5 10 75 5.003 4,002 3.03 25.3 134.0 64.8 10 TIBA 5 10 100 3.688 2,950 2.74 23.7 135.0 60.6 11 TIBA 5 1 75 trace 0 12 TIBA 5 2 75 trace 0 13 TIBA 5 5 75 0.126 101 4.14 40.6 136.4 66.7 14 TIBA 5 20 75 1.206 965 2.85 42.6 132.5 74.5 15 TIBA 5 50 75 0.632 506 2.11 59.6 132.6 74.5 16 TIBA 5 100 75 0.608 486 1.61 51.9 135.5 72.2 17 TIBA 1 10 75 0 0 18 TIBA 1 20 75 0.188 472 5.14 23.9 138.3 61.9 19 TIBA 1 30 75 1.002 4,008 3.80 24.4 136.6 67.2 20 TIBA 1 35 75 1.755 7,020 3.03 18.1 139.0 68.1 21 TIBA 1 40 75 1.592 6,368 3.54 16.8 136.3 55.5 22 TIBA 1 45 75 0.791 3,164 3.41 17.4 139.8 61.6 23 TIBA 1 50 75 0.615 2,460 2.81 17.0 138.5 67.6 24 [f] TIBA 5 10 75 0.981 785 2.78 24.4 135.2 65.8 [a] Unless otherwise stated, reactions were performed in a 300 mL pressure reactor using toluene (50 mL) as solvent for 15 min at 20 bar of eth ylene. [b] Determined by GPC analysis. [c] Determined by DSC. [d] Crystallinity c f f f = 293 Jg 1 for completely crystalline PE. [e] t = 30 min. [f] Pressure = 5 bar of ethylene.

PAGE 91

91 Figure 3 7 Activity (kg PE (molCr) 1 h 1 ) for complex 6 6 ( 6 ( ) Figure 3 8 13 C NMR of polyethylene sample in 1,3,5 trichlorobenzene d 3 at 130 C.

PAGE 92

92 Table 3 2 Activity comparison of homogeneous chromium monoalkyl based polyethylene polymerization systems. Monoalkyls g (mmol ) 1 h 1 bar 1 Cationic Monoalkyls MacAdams (2005) 0 Dohring (2000) 0 Bhandari (1995) 5 MacAdams (2005 22 Thomas (1988) 25 Neutral Monoalkyls Liang (1996) 0.15 Vidyaratna (2009) 28 Gibson (2000) 50 Gibson (1998) 70 Table 3 3 Activity comparison of homogeneous chromium dialkyl based polyethylene polymerization systems. Dialkyls g (mmol ) 1 h 1 bar 1 Heintz (1998) 20 Rogers (2000) 4,000 Dohring (2000) 5,240 Dohring (2001) N/A

PAGE 93

93 Table 3 4 Activity comparison of homogeneous chromium monochloride and dichloride based polyethylene polymerization systems. Monochloride & Dichlorides g (mmol ) 1 h 1 bar 1 Monochlorides Heinemann (1998) 24 Gibson (2000) 96 Huang (2009) 153 Xu (2007) 574 Xu (2011) 808 Sun (2011) 1,200 Dich lorides Rozenel (2009) 21 Ogata (2002) 36 Theopold (2002) 105 Kotov (2001) 286 Zhang (2011) 608 Zhang (2004) 2,000 Dohring (2001) 2,570 Enders (2001) 3,640 Jones (2002) 6,970 Dohring (2000) 14,800 Table 3 5 Activity comparison of homogeneous chromium dinuclear and pincer type based polyethylene polymerization systems. Dinuclear g (mmol ) 1 h 1 bar 1 Sun (2011) 213 Theopold (2002) 390 Pincer Type Fryzuk (1999) Very Low Matsunaga (1999) 500

PAGE 94

94 CHAPTER 4 COMPELLING MECHANISTIC DATA AND IDENTIFI CATION OF THE ACTIVE SPECIES IN TUNGSTEN CATALYZED ALKYNE POLYMERIZATIONS: CONVERSION OF A TRIANIONIC PINCER INTO A NEW TETRAANIONIC PINCER TYPE LIGAND 4.1 Introduction Following my work with the [NCN]Cr IV Me complex ( 6 ), supported by an NCN 3 trianionic pince r ligand, as a precatalyst for ethylene polymerization, my focus shifted to alkyne polymerization with the [ t t Bu)(THF) 2 complex ( 15 ), supported by an OCO 3 trianionic pincer ligand, which was first synthesized by Soumya Sarkar of the Veige group. 91 (Figure 4 1 ) Complex ( 15 ) represents the first trianionic pincer alkylidyne complex. Synthesis of the complex is straightforward. (Figure 4 2 ). 91 First, al coholysis between 1 equiv. of ( t BuO) 3 W C t Bu and the OCO 3 ([ t BuOCO]H 3 ) ( 2 ) trianionic pincer ligand in THF affords [ t BuOCHO]W CC(CH 3 ) 3 (O t Bu)(THF) ( 12 ), a five coordinate W(VI) complex in which the ligand binds in the diphenolate form. Treating complex 12 with methylene(triphenyl) phosphorane ( Ph 3 P=CH 2 ), a mild base, activates the aryl backbone and precipitates the trianionic pincer alkylidyne salt {[ t BuOCO]W CC(CH 3 ) 3 (O t Bu)}{PPh 3 CH 3 } ( 13 ). The phosphonium counterion is then removed by treating 13 with methyl triflate in Et 2 O, which results in th e O alkylation of the alkoxide to provide the neutral trianionic pincer alkylidyne [ t BuOCO]W CC(CH 3 ) 3 (Et 2 O) ( 14 ). Adding a small quantity of THF to an ether suspension of 14 produces the [ t t Bu)(THF) 2 complex ( 15 ). The [ t t Bu)(THF) 2 c omplex ( 15 ) is of interest because isolable high oxidation state alkylidyne catalysts receive considerable attention for their applications in catalysis, 223 226 one of which is the polymerization of unsaturated alk yne substrates. Catalysts that polymerize alkynes, specifically acetylene an d its derivatives, are of great

PAGE 95

95 interest both from a basic research and practical application because polyacetylenes conjugating polymers. These polymers possess a unique set of properties and thus represent an important class of functional materials. In particular, these polymers possess a wide range of physical properties including electrical conductivity, 227 231 paramagnetic susceptibility, 232,233 optical nonlinearity, 234 236 photoconductivity, 237,238 gas permeability, 239 242 liquid crystallinity 243,244 and chain helicity. 245 248 Unfortunately, unlike the diverse multitude of highly active ethylene polymerization precatalysts/catalysts, few alkyne polymerization ca talysts exist, and those that do fall short of their alkene polymerization counterparts, both in terms of activity and turnover number (TON). Additionally, known alkyne polymerization catalysts are highly limited in their substrate scope. Thus, substrate c atalyst matching is necessary. 70 Therefore, the development of catalysts capable of polymerizing a wide variety of acetylenes with high activity is important. Since oxidation state alkylidyne catalysts are known to polymerize a cetylene and its derivatives, our goal was to employ the [ t t Bu)(THF) 2 complex ( 15 ) in alkyne polymerization studies. The rationale for our optimism in the ability of complex 15 to polymerize acetylene and its derivatives is based on the following rationale. S urveying the various transition metal based catalysts capable of acetylene poly merization and their mechanisms shows that all known mechanisms share a common feature: an open or labile metal coordination site, so that each additional incoming alkyne substrate can bind to the metal center.

PAGE 96

96 The two main types of mechanisms for chain growth that have been identified are metathesis and insertion. The active species in the metathesis mechanism are typically metal alkylidenes 2,75 83 or alkylidynes 84 86 in which an alkyne adds via [2+2] cycloaddition to provide metallocyclobutenes or metallocyclobutadienes, respectively. This addition is followed by retrocycloaddition ; then subsequent addition of additional alkynes monomers promote chain growth. The active species for the insertion mechanism are typically metal alkyls 2,68 70 or alkylidynes 8 7 90 in which the alkyne inserts into a metal carbon bond to promote chain growth. Specifically for the case of metal alkylidynes, one proposed pathway involves cycloaddition to provide a metallocyclobutadiene followed by coordination by a second monomer and insertion to expand the ring (Figure 4 3 ). Again, in either case a prerequisite for alkyne polymerization is the ability of the catalyst to provide an open coordination site for the coordination and insertion of subsequent monomer units. Thus, ligands capable of forcing open or labile metal coordination sites are prerequisites for alkyne polymerization catalysts. Like the NCN 3 ligand, the OCO 3 ligand of complex 15 which is capable of supporting high oxidation state metal complexes, 95,98,100 103,110 cons trains three anionic donors to the meridonal plane. 96,108,249,250 Therefore, it provides the necessary open coordination sites for incoming alkyne substrates to interact with the metal (Figure 4 4 ). As predicted, [ t t Bu)(THF) 2 ( 15 ) does polymerize phenylacetylene and 1 phenylacetylene derivatives with high activity. Therefore, our approach for creating a coordinatively unsaturated tungsten alkylidyne species capa ble of alkyne polymerization seemed correct. However, detailed examination of the polymerization

PAGE 97

97 mechanism shows that complex 15 acts only as a precatalyst. The active catalysts are two complexes formed in situ which feature a newly formed tetraanionic p incer alkylidene ligand [O 2 C(R)C=] 4 where R = Ph and t Bu (Figure 4 5). In addition to this new form of a pincer type ligand, the mechanistic data presented herein provides compelling evidence for a new alkyne polymerization mechanism in which initial ace tylene addition forms a metallocyclopropene and subsequent insertion form s a metallocyclopentadiene. Overall, the mechansim appears more similar to proposed mechanism for acetylene cyclotrimerization. 251 254 4.2 Res ults and Discussion 4.2.1 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). Upon treating complex 15 with 2 equiv. of phenylacetylene in toluene d 8 at 35 C, complexes [O 2 C( t BuC=)W( 2 16 t Bu ) and [O 2 C(PhC=)W( 2 t Bu)] ( 16 Ph ) form in a 2:1 ratio. Additional ly, a small quantity of polyphenylacetylene (PPA) is produced ( Figure 4 6). Fortunately, both complexes are Et 2 O soluble, but the PPA is Et 2 O insoluble. Adding Et 2 O and filtering results in the separation of the Et 2 O insoluble PPA. Even more fortuitously, 16 t Bu and 16 Ph are easily separated as 16 Ph is pentane insoluble whereas 16 t Bu is pentane soluble. Adding pentane and filtering results in the segregation of 16 Ph a orange solid in 33% yield. The pentane soluble solution of 16 t Bu was reduced under vacuum yielding a yellow solid in 40% yield. A combination of 1 H, 13 C{ 1 H}, and 2D NMR were performed to unambiguously assign 16 t Bu and 16 Ph Full assignments can be found in the Appendix (Table A 1 ). 1 H NMR of complex 16 t Bu in toluene d 8 exhibits two si nglets in a 2:1 ratio at 1.14 and 0.93 ppm. These singlets correspond to the pendant aryl t Bu protons on the ligand and the t Bu

PAGE 98

98 protons on the alkylidene, respectively. Since both pendant aryl t Bu groups are equivalent in the 1 H NMR, complex 16 t Bu is C s s ymmetric in solution. In the 13 C{ 1 H} NMR, a resonance at 126.4 ppm corresponds to the C ipso carbon indicating that the backbone of the ligand is not directly attached to the W(VI) metal center. If it were, the resonance for such a carbon would typically be observed around ~ 200 ppm. Rather than being directly attached to the W(VI) metal center, the aryl backbone attaches to the carbon of a W=C alkylidene. The resonance for the W=C carbon appears downfield at 270.0 ppm in the 13 C{ 1 H} NMR. This resonance is co nsistent with a previously reported trianionic pincer tungsten alkylidene. 98 A multinuclear 1 H 13 C HSQC spectrum of 16 t Bu confirms the connectivity of the C ipso carbon with the W=CC(CH 3 ) 3 protons. T he compl ex possesses an 2 bound phenylacetylene. The proton on the 2 HC CPh moiety appears downfield at 11.95 ppm in the proton NMR. The 1 H NMR spectrum for 16 Ph in toluene d 8 also shows two singlets (1.18 and 1.68 ppm), which correspond to the t Bu pro tons on the ligand and the t Bu protons on the bound phenylacetylene, respectively, The two singlets are consistent with a C s symmetric complex. The C ipso carbon resonates at 125.9 ppm in the 13 C{ 1 H} NMR, again indicating that the backbone of the ligand is not directly attached to the W(VI) metal center. The aryl backbone attaches to the W=C carbon, which resonates at 252.6 ppm in the 13 C{ 1 H} NMR Similar to 16 t Bu a multinuclear 1 H 13 C HSQC NMR spectrum of 16 Ph displays long range coupling between the C ip so carbon and W=CPh fragment. Lastly, the proton on the 2 HC C t Bu moiety correlates with a downfield singlet at 11.56 ppm in the 1 H NMR. Single crystals amenable for X ray diffraction deposit from a concentrated

PAGE 99

99 solution of 16 Ph in Et 2 O at 35 C. Figure 4 7 depicts the molecular structure of 16 Ph the caption provides selected bond lengths and angles, and Table 4 1 lists X ray refinement data. Complex 16 Ph which is pseudo C s symmetric in the solid state, contains a W(VI) metal center in a non standard polyhedral geometry. The ligand chelates the W(VI) metal center through two phenolate donors with an O1 W1 O2 bond angle of 150.25(9) and an alkylidene connection. Interestingly, 16 Ph and 16 t Bu are the first complexes to feature the unique tridentate t etraanionic pincer type ligand. The W=C bond length (C33 W1) of 1.905(3) is significantly longer than the W(VI) alkylidyne bond length in 15 of 1.759(4) 91 and is consistent with previously reported trian ionic pincer W(VI) alkylidenes. 98,101 The coordinated THF is trans to the tungsten alkylidene; it experiences a strong trans influence as evidenced by the long W1 O3 bond length of 2.323(2) Due to the trans influ ence and the elongated bond length, the coordinated THF is likely labile based on the fact that the THF ligands in 15 are labile and also have long W O bonds (2.473(2) and 2.177(2) ). The coordinated alkyne is better represented in the resonance form o f a metallocyclopropene. The C32 C27 bond length (1.312(4) ) is significantly elongated form the typical C C bond length of 1.21 255 Therefore, it is better represented as a double bond. 255 Additiona lly, the W1 C32 bond length of 2.009( 3) and W1 C27 bond length of 2.044(3) are consistent with W C single bonds. 255 Lastly, the coordinated alkyne is significantly bend with a C32 C27 C28 bond angle of 138.4(3) which is closer to an sp 2 hybridized carbon (120 ) than for an sp hybridized alkyne. Comparable examples of an 2 bound acetylene to tungst en include W( 2 3 256 W(NPh)( o (Me 3 SiN) 2 C 6 H 4 )( 2 257 and others 258 260 These structural details

PAGE 100

100 imply that although the tungsten ion is formally a d 2 4+ ion, the metal ligand ba ckbonding makes the ion effectively a d 0 6+ ion (Figure 4 8 ). As mentioned, 16 t Bu and 16 Ph form initially in a 2 to 1 ratio from the reaction between 15 and phenylacetylene. Since a chemical reaction in which more than one product is formed is g enerally governed by either laws of thermodynamics or kinetics, studies were conducted to determine the relationship between 16 t Bu and 16 Ph Heating a solution of only 16 t Bu in toluene d 8 at 85 C and monitoring by 1 H NMR shows that 16 t Bu converts to 1 6 Ph (Figure 4 10). The two complexes achieve an equilibrium after 2.5 weeks of heating at 85 C. At equilibrium, integration of the respective protons on the 2 and 2 t Bu moieties indicates that 16 t Bu and 16 Ph exist in a 17: 83 ratio (K eq = 5). This ratio corresponds to a free energy difference of 1.14 kcal mol 1 at 85 C. The kinetic profile of the conversion of 16 t Bu into its equilibrium produ cts as monitored by 1 H NMR is consistent with a reversible first order reaction. Figure 4 11 depicts a plot of the respective integrated rate law; the slope equals 4.06(1) x 10 6 s 1 and corresponds to ( k 1 + k 1 ). Using the slope and the experimentally de termined K eq = k 1 / k 1 provides the individual rate constants for k 1 (3.38(1) x 10 6 s 1 ) and k 1 (6.73(2) x 10 7 s 1 ). These values are further corroborated by plotting ln[ 16 t Bu ] vs. time to provide k 1 (3.36(6) x 10 6 s 1 ) and independently plotting ln[ 16 Ph ] vs. time to provide k 1 (7.0(3) x 10 7 s 1 ) (Figure 4 12 ). Overall, these conversion studies show that the reaction between 15 and phenylacetylene produces complex 16 t Bu as the kinetic product while complex 16 Ph is the thermodynamic product (Figure 4 9 ).

PAGE 101

101 4.2.2 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (17 Ph). Treating 15 [ t BuOCO] W C C ( CH 3 ) 3 (THF) 2 with 1 equiv. of 1 phenyl propyne at 35 C in toulene d 8 yields [O 2 C( t BuC=)W( 2 17 t Bu ) and [O 2 C(PhC=)W( 2 t Bu)] ( 17 Ph ) in a 1:2 ratio as deter mined by 1 H NMR spectroscopy (Figure 4 13 ). Unlike the reaction between 15 [ t BuOCO] W C C ( CH 3 ) 3 (THF) 2 and 1 equiv. of phenylacetylene, no polymer forms during this reaction. 17 t Bu and 17 Ph are easily separated as 17 Ph is pentane insoluble whereas 17 t Bu is pentane soluble. Both complexes are light yellow solids. Interestingly, in contrast to the formed ratio between products 1 6 t Bu and 1 6 Ph (2:1), products 17 t Bu and 17 Ph initially form in a 1:2 ratio as determined by 1 H NMR spectroscopy. Heating a solution of 17 Ph at 135 C for one week and integrating the respective methyl protons on the 2 moiety show that 17 t Bu and 17 Ph establi sh a dynamic equilibrium in a 1: 3.8 ratio. This ratio corresponds to a free energy difference ( G (135 ) = 1.05 kcal mol 1 ). Therefore, 17 Ph is both the major kinetic and thermodynamic product from the re action between 15 and 1 phenyl propyne. A combination of 1 H, 13 C{1H}, and 2D NMR were performed to unambiguously assign 17 t Bu and 17 Ph Full assignments can be found in the Appendix ( Table A 2 ). In the 1 H NMR spectrum of 17 t Bu in toluene d 8 two sing lets appear at 0.87 and 1.20 ppm attributable to the two pincer aryl t Bu protons and the t Bu protons on the alkylidene. Since the two pincer aryl t Bu protons only produce one singlet peak, 17 t Bu is C s symmetric in solution. A peak at 3.34 ppm corresponds to the methyl protons on the 2 moiety. In the 13 C{ 1 H} NMR spectrum, a downfield signal appears at 200.2 ppm, which corresponds to the W= C carbon. Lastly, the C ipso carbon resonates at

PAGE 102

102 126.7 ppm. If this carbon is bound to the tungsten metal center it typically resonates around 200 ppm. Therefore, the central pincer ring does not bond directly to the tungsten metal center. The 1 H NMR spectrum for 17 Ph in toluene d 8 also shows two singlets (1.26 and 1.65 ppm), which correspond to the t Bu pro tons on the ligand and the t Bu protons on the bound phenylacetylene, respectively. The methyl protons on the 2 t Bu moiety appear as a singlet at 2.82 ppm. The 13 C{ 1 H} NMR spectrum shows the downfield signal for the W= C carbon at 251.7 ppm. Additionally, a resonance corresponding to the C ipso carbon appears at 127.7 ppm. Similar to the case for complex 17 t B u this resonance indicates that the pincer aryl ring is not bound directly to the tungsten metal center, and therefore, the C ipso W bond was broken during the course of the reaction. Single crystals amenable for X ray diffraction deposit from a concent rated solution of 17 Ph in Et 2 O at 35 C. Figure 4 14 depicts the molecular structure of 17 Ph the caption provides selected bond lengths and angles, and Table 4 1 lists X ray refinement data. Like 16 Ph complex 17 Ph is pseudo C s symmetric in the solid state. Additionally, the W(VI) ion does not conform to a standard polyhedral geometry. As suggested by C ipso carbon shift in the 1 H NMR, the ligand backbone is not bound through the C ipso carbon but rather through a newly generated alkylidene. As such, th e ligand binds in a tridentate tetraanionic form through the alkylidene and the two phenolate donors. The phenolate donors span the trans position with an O1 W1 O2 bond angle of 151.66(11) The C33 W1 bond length of 1.905(3) is consistent with previously reported W(VI) alkylidene complexes. 98,101 The tungsten alkylidene imparts a relatively strong trans influence on the trans coordinated THF as evidenced by the

PAGE 103

103 elongated W1 O3 bond length of 2.288(3) The bond le ngths of bonds W1 C27, W1 C32, and C32 C27 support the metallocyclopropene structure. The bond length of W1 C27 is 2.026(4) ; the bond length of W1 C32 is 2.030(4) Both bonds are in the range of W C single bonds. 255 The bond length of C32 C27 is 1.321(6) which is in the range of a C=C double bond. 255 Additionally, the bond angle for C32 C27 C28 (139.0(4) ), further supports the representation of the alkyne bound as a metallocyclopropene with the tungsten in the formal +6 oxidation state. 4.2.3 Kinetic Results of Phenylacetylene Polymerization by 15, 16 Ph, and 16 t Bu: Determination of the Active Catalyst. Complexes 15 16 Ph and 16 t Bu all catalyze phenylacetylene. To determine what, if any, the relationship is between complex 15 and complexes 16 Ph and 16 t Bu during the polymerization reaction, the kinetics of phenylacetylene polymerization by each complex were monitored. If in fact complex 15 is only a precatalyst and complexes 16 Ph and 16 t Bu are the active catalysts, the initial turnover frequency for the polymerization by 15 should be the weighted average of the initial turnover frequencies of the active catalysts, 16 Ph and 16 t Bu Figure 4 15 provides the catalytic turnover numbers (TON s) determined by quantitative yield (mg) of PPA vs. time (min) for the polymerization by 15 16 Ph and 16 t Bu respectively All polymerization reactions were completed in triplicate (only average value shown) with a substrate to catalyst loading ratio of 10,000:1. For the first two minutes of the reaction, complex 15 yields an the initial turnover frequency (TON vs. time) of 881 units per min. For the first two minutes of the reaction, 16 t Bu yields a turnover frequency of 1126 units per min and 16 Ph yi elds a turnover frequency of 433 units per min. Since treating complex 15 with 2 equiv. of

PAGE 104

104 phenylacetylene yields 16 t Bu and 16 Ph in a 2:1 ratio, the weighted average turnover frequency for 16 t Bu and 16 Ph is 895 units per min. This value closely match es the initial turnover frequency of 15 of 881 units per min which suggests that complex 15 acts only as a precatalyst while 16 t Bu and 16 Ph act as the active catalysts. Therefore, upon addition of excess phenylacetylene to 15 complexes 16 t Bu and 16 P h form initially and these complexes are then responsible for the propagating polymer chain. 4.2.4 Polymerization Results: Monosubstituted and Disubstituted Acetylenes Before the isolation of the active catalysts, 16 t Bu and 16 Ph complex 15 the precatalyst was screened as an alkyne polyermizatio n catalysts with the substrates phenylacetylene, 1 ethynyl 4 fluorobenzene, and 1 ethynyl 4 fluorobenzene. Indeed, complex 15 poymerizes these acetylene derivati ve with high acitivties and turn over numbers. Once the active catalysts were identified and separated, a more thorough set of substrates including monosubstitued and disubstitued acetylene monomers were screened using both 15 and 16 t Bu The active catalysts, 16 t Bu and 16 Ph form in situ open the addition of excess phenylacetylene. As shown in the kinetic results section, the ability to separate these two active catalysts offers a significant advantage. Specifically, since 16 t Bu catalyzes the polymerization of phenylacetylen e more quickly and with higher T ON than 16 Ph using only 16 t Bu will yield better polymerization results than the precatalyst 15 Therefore, 15 and 16 t Bu were tested for the polymerization activity with a variety of monosubstitued and disubstitued acetylene monomers (Table 4 2 and 4 3) In a typical reaction, a toluene solution of the catalyst was added to the stirring solution of acetylene mo nomer and toluene in a nitrogen filled glove box. Standard

PAGE 105

105 ei either 15 or 16 t Bu Et 2 O and THF were screened as potential solvent s ; however, both prove problematic. THF suppresses the reaction, most likely due to competitive coordination at tungsten, and Et 2 O precipitates the polymer. Af ter addition, the reaction was vigorously stirred for 1 h, then quenched outside of the glove box with methanol. The resu lting monomer was dried in vacuo and then weighted to provide the quantitative yield and turnover number (TON). Polymer chracterization includes FTIR, 1 H NMR, and gel permeation chromatography (GPC) (for all samples soluble in THF) to determine M w M n and M w /M n Both complex 15 and 16 t Bu polymerize phenylacetylene, 1 ethynyl 4 methoxybenzene, 1 ethynyl 4 fluorobenzene and 1 decyne with remarkably high yield and TON at 25 C. However, neither 3,3 dimethyl 1 butyne nor trimethylsilylacetylene polymerizes at 25 C in the presence of 15 and 16 t Bu As both these substrates contain more sterically bulky groups, t Bu and trimethylsilyl, respecti vely, these bulky groups likely slow the rate of coordination and insertion of the monomer units. Therefore, the reaction temperature was raised to 75 C for these substrates. Upon heatin g the se polymerization reaction solution s at 75 C with a smaller sub strate to catalyst ratio (1,000:1), both 3,3 dimethyl 1 butyne and trimethylsilylacetylene polymerize in relatively good yield. Unfortunately, highly acidic substrates, 1 ethynyl 4 nitrobenzene and methyl propiolate do not polymerize even with elevated tem peratu res and smaller substrate to catalyst ratios. Lastly, 16 t Bu polymerizes the disubstituted acetylene, 1 phenyl 1 propyne, over a period of 24 h at 75 C and a substrate to catalyst ratio of 100 to 1.

PAGE 106

106 The monomers all absorb IR radiation near 3300 an d 2100 cm 1 corresponding to C H and C C stretching vibrations, respectively. IR spectra of the the corresponding polyacetylenes do not show these stretching vibrations but they do show a C=C stretching band at approximately 1595 cm 1 which is consisten t with literature precendence. 261 263 All the poly(phenylacetylene) polymers are dark red orange in color. The polymer of 3,3 dimethyl 1 butyne is a white stringy solid, and the polymer of 1 decyne is a white rubber y solid. The polymer of trimethylsilylacetylene is a yellow powder insoluble in most organic solvents and only partially soluble in methylene chloride. The poly m er of 1 phe nyl 1 propyne is a white string y solid. The microstructure of phenylacetylene, spec ifically, was determined by 1 H NMR The 1 H NMR spectrum of PPA reveals broad resonances at 6.7 and 5.8 ppm, corresponding to the trans vinyl protons and aromatic protons and the cis vinyl protons, respectively. Integrating the cis vinyl protons relative to the trans vinyl protons and the aromatic protons provides an approximate value for the cis/trans content of the double bonds within PPA. 262 The PPA sa mple con tains approximately 90:10 cis/trans content. The polymers of 1 ethynyl 4 fluorobenzene and 1 ethynyl 4 methoxybenzene possess 70 80% cis content. Based on the mechanistic details to follow, it is difficult to explain the trans conformation from a m echanistic perseptive. However, polyphenylacetylene will undergo the cis trans isomerization upon heating. 264 During the polymerization conducted with 15 16 t Bu and 16 Ph the temperature is not controlled and the highly exothermic insertion reaction results in a rapid rise in temperature. This temperature rise may explain the existence o f trans content within the polymer. Further microstructure analysis was attained by heating the PPA sample to 215

PAGE 107

107 C and then examining the ratio of cyclized products by 1 H NMR according to known methods. 261,265 As mentioned, heating PPA induces cis/trans isomerization. At 215 C, the polymer chain undergoes electrocyclization, chain scission, then finally aromatization to form 1,3,5 and 1,2,4 triphenylbenzene, corresponding to a head to tail or head to head mon omer arrangement, respectively. The 1 H NMR spectrum of the heated PPA reveals signals attributable to 1,3,5 and 1,2,4 triphenylbenzene in a 94:6 ratio, indicative of predominantly head to tail units. Unfortunately, the macrostructure of the PPA could not be determined despite taking tunneling electron microscope (TEM) images of the polymer. It is plausible that the polymers may be cyclic especially based on the mechanism detailed in the next section. Lastly, while it is plausible that metathesis products could form during the course of the reaction, periodic GC analysis of the polymerization solution shows no metathesis products (diphenylacetylene or ethyne). The polymers possess a wide range of M w M n and M w /M n values. The monomer, 1 de cyne, produces the highest M n with a M n of 130.7 x 10 3 Da for the polymer using 15 and 119.4 x 10 3 Da for the polymer using 16 t Bu The lowest M n occurs for poly(3,3 dimethyl 1 butyne) with a M n of 2.1 x 10 3 Da for the polymer using 15 and 2.1 x 10 3 for th e polymer using 16 t Bu Most of the polydispersities (M w /M n ) are modest compared to the large number of living phenylacetylene polymerization systems. 79,81,83,266 269 However, the polydispersities for poly(1 decyne) and poly(3,3 dimethyl 1 butyne) are low. For poly(1 decyne) M w /M n is equal to 1.27 and 1.37 for 15 and 16 t Bu respectively. For all polymers, the M n value is lower than the theoretical value would be based on one

PAGE 108

108 chain per metal. Therefore, on average ea ch metal is responsible for more than one chain. 4.2.5 Synthesis of [OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] (18A) and [OC( t BuC=)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] (18B). As previously mentioned, two types of mechanisms for the polymerization of substituted acetylenes have been identified: metathesis and insertion. As we were curious as to the mechanism of our catalyst, experiments were conducted to probe the mechanism of polymerization. Our first step was to identify the species that results from addition of one monomer u nit to either 16 t Bu and 16 Ph Unfortunately the addition of 1 equiv of phenylacetylene to either complex could not be controlled, as this addition lead s solely to the formation of polymer. Therefore, a more sterically bulky monomer (1 phenyl propyne) was chosen to slow down the rate of insertion. Fortunately, treating 16 t Bu with 10 equiv. of MeC CPh in toluene d 8 at 75 C selectively incorporates one additional acetylene unit into the metallocyclopropene moiety of 16 t Bu The MeC CPh inserts to form a metallocyclopentadien e ring according to Figure 4 16 The insertion yi elds two isomers via 1,2 versus 2,1 insertion [OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] ( 18A ) and [OC( t BuC=)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] ( 18B ) in a 2 to 1 ratio Unfortunately, both 18A and 18B are pentane soluble and thus inseparable. Nevertheless, a comb ination of 1 H, 13 C{ 1 H}, and 2D NMR were performed to unambiguously assign 18A and 18B Full assignments can be found in the Appendix (Table A 3 ). Three distinct singlets at 1.50, 0.93, and 1.42 ppm appear in the 1 H NMR of 18A ; these singlets correspond to the pincer aryl t Bu protons, alkylidene t Bu protons, and metallocyclopentadiene methyl protons, respectively, and correctly integrate in a

PAGE 109

109 18: 9: 3 ratio. The C ipso carbon resonates at 105.0 ppm in the 13 C{ 1 H} NMR, and the W=C carbon resonates at 310.0 ppm Therefore, the unique structural feature of the aryl backbone bound to the W=C alkylidene remains intact as the MeC CPh inserts into the metallocyclopropene moiety. Similar to 18A 18B exhibits three distinct singlets at 1.44, 0.96, and 1.94 ppm correspo nding to the pincer aryl t Bu protons, alkylidene t Bu protons, and metallocyclopentadiene methyl protons, respectively. These three resonance s also correctly integrate in a 18: 9: 3 ratio. Although 18A and 18B are both pentane insoluble and thus inseparabl e, single crystals of 18A amenable to X ray diffraction experiments deposit from a concentrated solution containing both 18A and 18B in Et 2 O at 35 C. Figure 4 17 depicts the molecular structure of 18A the caption provides selected bond lengths and angle s, and Table 4 1 lists X ray refinement data. Complex 18A is pseudo C s symmetric in the solid state, and it contains a W(VI) metal center in a distorted trigonal bipyramidal geometry with the oxygen atoms in the axial plane. The ligand remains unaltered as it binds in a tridentate tetraanionic form through two phenolate donors and an alkylidene. The newly inserted MeC CPh forms a metallocyclopentadiene with alternating single and double bonds. The W1 C27 bond length (2.062(4) ) and W1 C42 bond length (2.070(4) ) are in the range of W C single bonds. 255 The C27 C34 bond length (1.354(6) ) and C35 C42 bond length (1.342(5) ) are in the range of C=C double bonds, 255 and the C34 C35 (1.495(5) ) bond length is in the range of a C C single bond. Only a f ew examples of crystallographically characterized tungsten metall ocyclopentadienes exist, 270,271 and only one such example CpW[ 2 C(CF 3 )=C(CF 3 )C(CF 3 )=C(CF 3 )](S i Pr)(4 MeC 6 H 4 NC) 2 272 involves a mononuclear

PAGE 110

110 complex. Both complexes exhibit structural similarities. For example, both metallocyclopentadiene moieties are approximately planar with localized C=C double bonds. Similar to the observed head to tail arrangement in the cha racterization of PPA, 18A presents a ring system with the predominant head to tail arrangement as well. However, the ratio of 18A to 18B ( 2: 1) falls short of the experimentally determined >94:6 ratio of head to tail arrangement in PPA. The discrepancy betw een the ratios likely occurs because of the greater steric bulkiness of 1 phenyl propyne relative to phenylacetylene. This steric bulkiness slows the rate of coordination and insertion of the disubstituted 1 phenyl propyne as compared to the monosubstitute d phenylacetylene. 4.3 Conclusions 4.3.1 Formal Reductive Alkylidyne Migratory Insertion into a M arene Bond Complex 15 converts into 16 t Bu and 16 Ph via an apparent direct migration of an alkylidyne into the metal arene bond. However, this is not necessarily the case. Rather, a more circuitous route may occur, giving the overall appearance that an alkylidyne insertion occurs. Two possible routes could result in the overall formal reductive alkylidyne migratory insertion (Figure 4 18 ). In A the reaction proceeds d irectly from the alkylidyne functionality. In B the reaction proceeds through a metallocyclobutadiene. In either case, a metallocyclobutadiene must form as a necessary intermediate since addition of phenylacetylene to 15 produces both 16 t Bu and 16 Ph Evidence indicates that the direct insertion pathway likely does not occur. Rather, the reaction more likely proceeds through the metallocyclobutadiene intermediate. Since complex 15 donor ligands such as THF and Et 2 O, 91 acid character of the acetylene likely plays a role in inducing the

PAGE 111

111 acids, like carbon monoxide (CO), should be able to induce the transformation. This will tell which pathway the reaction proceeds through because 15 and CO cannot achieve the metallocyclobutadiene intermediate required for pathway B In a sealable NMR tube, no reaction occurs when exposing 15 to 1 atm of CO in toluene d 8 Therefore, the mechanism more than likely proceeds through the metallocyclobutadiene intermediate. 4.3.2 Active Catalyst and Activity Kinetic analysis of the initial turnover frequencies for the polymerizations by 16 t Bu and 16 Ph indicates that their weighted average is nearly equal to that of complex 15 which identifies 16 t Bu and 16 Ph as the active catalysts. Isolated complex 16 t Bu is highly active and long lived and will polymerize a comparatively wide variety of substrates. As mentioned previously, one major problem for the field of alkyne polymer ization is that currently known alkyne polymerization catalysts require specific substrate catalyst matching because each catalyst possesses limited substrate scope. For example, typically, functionalized 1 phenylacetylenes are poly merized only by Rh based catalysts, although non functionalized phenylacetylene can be polymerized by a wide variety of catalysts. However, Rh based catalysts are typically ineffective at polymerizing disubstituted acetylenes because disubstituted acetylen es are sterically more crowded than their monosubstituted counterparts. As a result, a vast majority of the effective disubstituted acetylene polymerization catalysts are group 5 and 6 transition metal catalysts. Remarkably, complex 16 t Bu polymerizes bot h phenylacetylene and 1 phenylacetylene derivatives. 70 Thus, 16 t Bu is a rare example of a tungsten catalyst

PAGE 112

112 capable of polymerizing phenylacetylene as well as its functionalized cousins. Additionally, not only does 16 t Bu polym erize monosubstituted monomers, but also polymerizes the disubstituted monomer, 1 phenyl 1 propyne. Therefore, 16 t Bu is a n even more rare example of an acetylene polymerization catalyst capable of polymerizing multiple substrate classes. In addition to it s wide substrate compatibility, 16 t Bu more remarkably, provides exceptionally high turnover numbers and activities as compared to known alkyne polymerization catalysts. Complexes 15 16 Ph and 16 t Bu were all screened to find the highest attainable turn over number and catalytic activity. In all cases, 16 t Bu supplies the best catalytic values. With a substrate to catalyst loading of 25,000 to 1, 16 t Bu turns over approximately 17,233 phenylacetylene monomer units. Furthermore, 16 t Bu polymerizes the m onomers, phenylacetylene and 1 decyne, with catalytic activities up to 5.64 x 10 6 g PPA mol 1 h 1 and 7.98 x 10 6 g PA mol 1 h 1 respectively. (Table 4 4). To the best of our knowledge, 16 t Bu is the most active phenylacetylene polymerization W based catalys t, 71,73,77,78,87 89,273 280 and more active than all known Mo 71,73,278 281 Rh 262,274,275,282 288 Ir 289 291 and Pd based catalysts. 292 296 Our explanation for the high activity is the coordinatively unsaturated metal center created by the tetraanionic pincer ligand. The three anionic ligands bearing a total 4 charge are constrained to a meridonal plane, thus allowing three available coordination sites (Figure 4 19 ). The structural evidence of a metallocyclopentadiene ( 18A ) provides compelling evidence for an insertion/ring expansion mechanism. Therefo re, an open coordination site is necessary for high activity, and the tetraanionic ligand provides this condition.

PAGE 113

113 4.3.3 Polymerization Mechanism Complexes 18A and 18B provide reasonable evidence for an insertion/ring expansion polymerization mechanism for chai n propagation as depicted in Figure 4 20 An acetylene first adds to 15 form a metallocyclopropene with an 2 bound acetylene; then, a second acetylene inserts to form a metallocyclopentadiene. Based on thermolysis studies, the majority of monomer units in sert with a head to tail orientation. 91 This stepwise addition represents a unique acetylene polymerization mechanism, as compared to the known metal alkyl bond insertion, 2,68 70 metal alkylidene metathesis, 75 78 and metal alkylidyne insertion 84 86 and metathesis mechanisms. 87 90 The sequential i nsertion of an acetylene into an expanding macrocycle parallels the proposed mechanism for the cyclotrimerization of alkynes. The cyclotrimerization of acetylene involves the oxidative coupling of two alkyne ligands to generate a metallocyclopentadiene. Th en, a third acetylene coordinates and inserts in the M bond to form a metallocycloheptatriene. The species finally undergoes reductive elimination to provide a cyclotrimerized product. 251 254 The mechanism prese nted herein represents a novel case of the proposed cyclotrimerization mechanism, whereby oxidative coupling occurs to form the metallocyclopentadiene, and then, a third acetylene coordinates and inserts in the M bond to form a metallocycloheptatriene. At this point, however, reductive elimination is slow, and insertion of additional monomer units occur s instead Evidence to support these claim comes from the molecular weights of the polymers obtained from the different monomers. For example, the polyme r formed from 3,3 dimethyl 1 butyne possesses a M n of 2.1 x 10 3 Da, whereas the polymer formed from 1 decyne possesses a M n of 119.4 x 10 3 Da. The more

PAGE 114

114 sterically bulky 3,3 dimethyl 1 butyne presumably leads to a higher rate of reductive elimination and a lower rate of propagation, thus providing lower molecular weight polymers. 4.3.4 Effect of Substrate Choice on Polymerization The polymerization results on a wide variety of monosubstituted substrates show that the most acidic acetylene monomers do not polym erize. Whether or not the acidity plays a significant role in determining how much poly(acetylene) forms, however, is not known. Among the phenylacetylene monomers, the least acidic monomers, 1 ethynyl 4 methoxybenzene and phenylacetylene, yield the highes t amount of polymer. As the acidity of the terminal proton increases to 1 ethnyl 3,5 bis(trifluoromethyl)benzene, the resulting amount of polymer rapidly decreases 297,298 T he most acidic monomer, 1 ethnyl 4 nitrob enzene, does not polymerize at all for either 1 5 or 16 t Bu T he results for the other alkynes are consistent with this observatio n. The monomers 1 decyne, 3,3 dimethyl 1 butyne and trimethylacetylene, which are less acidic than methyl propiolate, all polym erize b ut methyl propiolate does not. Adding methyl propiolate to 1 5 forms a metallocyclopropene with a 2 HC CCO 2 CH 3 (Figure 4 21 ); however, no further insertion and polymerization occurs. Upon addition of either 1 ethnyl 4 nit robenzene or methyl propiola te the reaction mixtures immediately turn dark brown, an observation not seen for all o ther polymerization reactions. As mentioned, an immediate and clearly discernible reaction occurs upon addition of 1 ethnyl 4 nitrobenzene to either 1 5 or 16 t Bu ; howev er, this reaction does no t lead to any polymer. So what reaction occurs between an acidic terminal alky ne and the tungsten complexes? To explore this reaction, the product of the reaction between 1 5 and 1 equiv HC p NO 2 ) at 25 C was probed in toluene d 8 by 1 H NMR, 13 C{ 1 H},

PAGE 115

115 and 2 D NMR techniques 1 H NMR of the product mixture clearly shows the presence of p NO 2 ) with the terminal proton intact. However, the two distinct TH F molecules for complex 1 5 are no longer present; rather, the two THFs are equivalent and unbound to the tungsten metal center w ith peaks at 3.55 and 1.34 ppm. Additionally, the tert butyl protons from the tungsten alkylidyne are shifted downfield from 0.5 5 to 0.84 ppm. Despite the fact that HC p NO 2 ) remains p NO 2 ) to 1 5 1 H NMR, 13 C{ 1 H}, and 2 D NMR techniques were used to determine the structure of the resulting complex, although the absolute structure could not be full y determined. ( Figure 4 22 ). Upon addition of HCCPh( p NO 2 ) to 1 5 a tungsten alkylidene ( 20 ) (with no hydrogen) forms with an attachment to the C ipso carbon The tungsten alkylide ne carbon appears at 280.7 ppm in the 13 C{ 1 H} NMR which is consistent with pr evi ously reported tungsten alkylide nes, while the C ipso carbon appears at 124.8 ppm. The 13 C{ 1 H} NMR shift for the C ipso carbon shows that it is not attached to the tungsten metal center. No proton signal couples to the C ipso carbon, as there is no cross p eak in the gHSQC spectrum, and quenching the complex with H 2 O yields the OCO 3 ligand without the C ipso H proton. Most confusingly, NMR spectroscopy techniques do not show any 2 HC CPh NO 2 or any solvent bound to the tungsten metal center in 20 It is unl ikely that 20 exists as the portrayed fragment (an 8 12 electron species) without any additional ligand bound to the tungsten metal center due to its extreme electronic and coordinative unsaturation. Unfortu nately, whether 20 exists as a dimer or whether the nitro group chelates to tungsten metal center could not be determined, and all attempts to isolate

PAGE 116

116 20 were unsuccessful. Upon trying to remove the solvent in vacuo this species decomposes into multiple unidentifiabl e species. Additional experiments show that addition of a catalytic quantity of HC CPh( p NO 2 ) (0.2 5 mol%) in toluene d 8 provides 20 as well. This suggests that HC CPh( p NO 2 ) acts catalytically. Furthermore, heating complex 1 5 for 1 day at 85 C in toluene d 8 also provides 20 (Figure 4 23 ). Attempts to isolate the tungsten alkylidene formed by the addition of HC CPh( p NO 2 ) to 1 were conducted in cyclohexane d 12 C omplex 1 5 undergoes a similar reaction in cyclohexane d 12 as it does in toluene d 8 as evidenced by 1 H NMR, 13 C{ 1 H} and 2 D NMR. 1 H NMR in cyclohexane d 12 of the product mixture clearly shows the presence of 1 equiv of HC CPh( p NO 2 ) with the terminal proton intact. The two THFs are equivalent and unbound to the tungsten metal center with peaks at 3.67 and 1.74 ppm. The tungsten alkyl ide ne carbon (with no hydrogen) appears at 297.6 ppm in the 13 C{ 1 H} NMR, while the C ipso carbon appears at 124.8 ppm. The 13 C { 1 H} NMR shift for the C ipso carbon again shows that it is not attached to the tungsten metal center, and n o proton signal couples to the C ipso carbon 4.4 Experimental Section 4.4.1 General Considerations Unless specified otherwise, all manipulations were performed under an inert atmosphe re using glove box techniques. Tetrahydrofuran (THF), pentane, hexane, diethyl ether (Et 2 O), toluene and be nzene (C 6 H 6 ) were dried using a GlassCont our drying column. C 6 D 6 (Cambridge Isotopes) was dried over sodium benzophenone ketyl, distilled or vacuum transferred and sto red over 4 molecular sieves. Toluene d 8 (Cambridge Isotopes) was dried over phosphorus pentoxide (P 4 O 10 ), distilled and stored

PAGE 117

117 over 4 molecular sieves. [ t BuOCO]H 3 94 and [ t t Bu)(THF) 2 91 were prepared according to literature procedure. Phenylacetylene, 1 phenyl 1 propyne, 1 ethynyl 4 methoxybenzene, 1 ethynyl 4 fluorobenzene, 1 ethnyl 4 nitrobenzene, 1 ethnyl 3,5 bis( trifluoromethyl)benzene, 1 decyne, 3,3 dimethyl 1 butyne, trimethylsilylacetylene, methyl propiolate and 1 phenyl 1 propyne were purchased from Sigma Aldrich, degassed, dried over activated 4 molecular sieves and filtered through a column of basic alumin a prior to use. 4.4.2 Analytical Techniques 4.4.2.1 NMR techniques : NMR spectra were obtained on Varian Gemini 300 MHz, Varian VXR 300 MHz, Varian Mercury 300 MHz, Varian Mercury Broad Band 300 MHz, Varian INOVA 500 MHz, or Varian INOVA2 500 MHz spectrometers. Chemical (ppm). For 1 H and 13 C NMR spectra, the residual solvent peak was referenced as an internal reference. 4.4.2.2 IR techniques : Infrared spectra were obtained on a Thermo scientific Nicolet 6700 FT IR. Spectra of solids were measured as KBr discs. 4.4.2.3 GPC techniques : Gel permeation chromatography (GPC) was performed with a Waters Associates GPCV2000 liquid chromatography system using an internal differential refractive index detector (DRI) and two Waters Styragel HR 5E columns with HPLC grade T HF as the mobile phase at a flow rate of 1.0 mL/min. Injections were made at 0.1 % w/v sample concentration usin Retention times were calibrated

PAGE 118

118 against narrow molecular weight polystyrene standards (Polymer Laboratories; Amherst, MA). 4.4.2.4 Elemental analysis : Combustion analyses were performed at Complete Analysis Laboratory Inc., Parsipp any, New Jersey. 4.4.3 Synthesis of [O 2 C( t BuC=)W( 2 t Bu). In a nitrogen filled glove box, a glass vial was charged with [ t BuOCO] W C( t Bu) (THF) 2 ( 1 5 ) (0.500 g, 0.650 mmol) in toluene (10 mL) and cooled to 35 C Phenylacetylene (146 L, 1.332 mmol) was added with stirring. The solvent was removed in vacuo. The resulting solid was dissolved in diethyl ether (10 mL) which precipita ted polyphenylacetylene (PPA). The mixture was filtered to remove the PPA, and the filtrate was removed in vacuo. Pentane (10 mL) was added, resulting in a yellow orange preci pitate and orange supernatant. The mixture was filtered to separate the yellow orange precipi tate from the orange solution. The orange solution was reduced under vacuum to yield light orange complex 16 t Bu Yield (205 mg, 40%). 1 H NMR (500 MHz, C 6 D 6 (ppm)): 12.01 (s, 1H, W C H ), 7.98 (d, 2H, Ar H ) 7.49 (d, 2H, Ar H ), 7.43 (t, 1H, Ar H ), 7.37 (d, 2H, Ar H ), 7.27 (t, 1H, Ar H ), 7.23 (d, 2H, Ar H ), 7.22 (t, 1H, Ar H ), 6.83 (t, 2H, Ar H ), 1.17 (s, 18H, C(C H 3 ) 3 ), 0.99 (s, 9H, C(C H 3 ) 3 ). 13 C{ 1 H} NMR (125.6 MHz, C 6 D 6 C Ph), 201.0 (s, W C C(CH 3 ) 3 ), 188.6 (s, W C H), 169.3 (s, C aromatic), 153.8 (s, C aromatic), 140.2 (s, C aromatic), 138.4 (s, C aromatic), 133.4 (s, C aromatic), 131.6 (s C, aromatic), 131.2 (s, C, aromatic), 129.8 (s, C, aromatic), 129.4 (s, C, aromatic), 129.2 (s, C, aromatic), 128.8 (s, C, aromatic), 127.2 (s, C, aromatic), 126.7 (s, C, aromatic), 119.7 (s, C, aromatic), 47.1 (s, W=C C (CH 3 ) 3 ), 36.8 (s, W=CC( C H 3 ) 3 ), 35.3 (s, C (CH 3 ) 3 ), 30.8 (s, C( C H 3 ) 3 ). Anal. Calcd

PAGE 119

119 for C 43 H 50 O 3 W: C, 64.66; H, 6.31. Found: C, 63.82; H, 6.26. 4.4.4 Synthesis of [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). In a nitrogen filled glove box, a glass vial was charged with [ t BuOCO] WC( t Bu) (THF) 2 ( 1 5 ) (0.500 g, 0.650 mmol) in toluene (10 mL) and cooled to 35 C Phenylacetylene (146 L, 1.332 mmol) was added with stirring. The solvent was re moved in vacuo. The resulting solid was dissolved in diethyl ether (10 mL) which precipita ted polyphenylacetylene (PPA). The mixture was filtered to remove the PPA, and the filtrate was removed in vacuo. Pentane (10 mL) was added, resulting in a yellow ora nge preci pitate and orange supernatant. The yellow orange solid was isolated via filtration and then was washed with additional cold pentane (5 mL) to yield complex 16 Ph Single crystals were obtained by cooling an ether solution of 16 Ph at 35 C for 12 h. Yield (169 mg, 33%). 1 H NMR (500 MHz, C 6 D 6 (ppm)): 11.63 (s, 1H, W C H ), 7.50 (d, 2H, Ar H ) 7.32 (d, 2H, Ar H ), 7.29 (t, 1H, Ar H ), 7.18 (d, 2H, Ar H ), 6.98 (d, 2H, Ar H ), 6.84 (d, 2H, Ar H ), 6.72 (t, 2H, Ar H ), 6.55 (t, 1H, Ar H ), 1.69 (s, 9H, C(C H 3 ) 3 ), 1.21 (s, 18H, C(C H 3 ) 3 ). 13 C{ 1 H}NMR (125.6 MHz, C 6 D 6 C Ph), 213.9 (s, W C C(CH 3 ) 3 ), 188.5 (s, W C H), 167.6 (s, C aromatic), 152.7 (s, C aromatic), 145.5 (s, C aromatic), 137.9 (s, C aromatic), 133.2 (s, C aromatic), 131.8 (s, C aromatic), 131.3 (s, C aromatic), 130.8 (s, C aromatic), 128.8 (s, C aromatic), 127.6 (s, C aromatic), 127.1 (s, C aromatic), 126.7 (s, C aromatic), 126.5 (s, C, aromatic), 120.0 (s, C aromatic), 40.3 (s, W C C (CH 3 ) 3 ), 35.5 (s, C (CH 3 ) 3 ), 32.0 (s, W CC( C H 3 ) 3 ), 31.0 (s, C( C H 3 ) 3 ). Anal. Calcd for C 43 H 50 O 3 W: C, 64.66; H, 6.31. Found: C, 63.76; H, 6.34. 4.4.5 Synthesis of [O 2 C( t BuC=)W( 2 t Bu) In a nitrogen filled glove box, a glass vial was charged with

PAGE 120

120 [ t BuOCO] WC ( t Bu)(THF) 2 ( 1 5 ) (0.400 mg, 0.520 mmol) in toluene (10 mL) and cooled to 35 C 1 phenyl 1 propyne (65.7 L, 0.525 mmol) was added with stirring. The solvent w as removed in vacuo. Pentane (10 mL) was added resulting in a yellow precipit ate and an orange supernatant. The mixture was filtered to separate the yellow precipi tate from the orange solution. The orange solution was reduced under vacuum to yield light or ange complex 17 t Bu Unfortunately, due to its pentane solubility, the complex could not be completely isolated from pentane soluble contaminants. Yield (90 mg, 21%). 1 H NMR (500 MHz, C 6 D 6 (ppm)): 7.83 (d, 2H, Ar H ), 7.48 (d, 2H, Ar H ), 7.44 (t, 2H, Ar H ), 7.29 (d, 2H, Ar H ), 7.26 (d, 2H, Ar H ), 7.26 (d, 1H, Ar H ), 7.21 (t, 1H, Ar H ), 6.84 (t, 2H, Ar H ), 3.34 (s, 3H, W CC H 3 ), 0.93 (s, 9H, W CC(C H 3 ) 3 ), 1.23 (s, 18H, C(C H 3 ) 3 ). 4.4.6 Synthesis of [ O 2 C(PhC=)W( 2 t Bu)] (17 Ph) In a nitrogen filled glove box, a glass vial was charged with [ t BuOCO] WC ( t Bu)(THF) 2 ( 1 5 ) (0.400 mg, 0.520 mmol) in toluene (10 mL) and cooled to 35 C 1 phenyl 1 propyne (65.7 L, 0.525 mmol) was added with stirring. Th e solvent was removed in vacuo. Pentane (10 mL) was added resulting in a yellow precipit ate and an orange supernatant. The yellow solid was isolated via filtration and then was washed with additional cold pentane (5 mL) to yield complex 17 Ph Single cryst als were obtained by cooling an ether solution of 17 Ph at 35 C for 12 h Yield (190 mg, 45%). 1 H NMR (500 MHz, C 6 D 6 (ppm)): 7.44 (d, 2H, Ar H ), 7.29 (t, 4H, Ar H ), 7.21 (t, 1H, Ar H ), 6.95 (t, 2H, Ar H ), 6.81 (t, 2H, Ar H ), 6.68 (t, 1H, Ar H ), 6.55 (d, 2H, Ar H ), 2.88 (s, 3H, W CC H 3 ), 1.65 (s, 9H, W CC(C H 3 ) 3 ), 1.29 (s, 18H, C(C H 3 ) 3 ). 13 C{ 1 H}NMR (125.6 MHz, C 6 D 6 m)): 252.0 (s, W= C Ph), 209.6 (s, W C C(CH 3 ) 3 ), 197.5 (s, W C H), 168.3 (s, C aromatic), 152.3 (s, C aromatic), 149.7 (s, C aromatic), 138.1 (s, C

PAGE 121

121 aromatic), 133.0 (s, C aromatic), 131.7 (s, C aromatic), 130.7 (s, C aromatic), 130.5 (s, C aromatic), 1 29.0 (s, C aromatic), 128.8 (s, C aromatic) 127.9 (s, C aromatic), 126.6 (s, C aromatic), 126.0 (s, C aromatic), 119.8 (s, C aromatic), 41.4 (s, W C C (CH 3 ) 3 ), 35.6 (s, C (CH 3 ) 3 ), 31.6 (s, W CC(C H 3 ) 3 ), 30.8 (s, C( C H 3 ) 3 ), 20.2 (s, W C C H 3 ). Anal. Calcd fo r C 44 H 52 O 3 W: C, 65.02; H, 6.45. Found: C, 65.14; H, 6.35. 4.4.7 Synthesis of [OC( t BuC=)O]W[ 2 C(Ph)=C(Me)C(H)=C(Ph)] (18A) and [OC( t BuC=)O]W[ 2 C(Me)=C(Ph)C(H)=C(Ph)] (18B). In a nitrogen filled glove box, a J Young tube was charged with [O 2 C( t BuC)=W( 2 t B u)] ( 16 t Bu ) (0.020 g, 0.025 mmol) and toluene d 8 (5 mL). 1 phenyl 1 propyne (31.5 L, 0.25 mmol) was added. The reaction vessel was heated at 85 C for 24 h. The solvent was removed in vacuo. Pentane (10 mL) was added, resulting in a white precipitate (tr ace pol ymer) and a green supernatant. The mixture was filtered to separate the white precip itate from the green solution. The green solution was reduced under vacuum and inspected in toluene d 8 by 1 H NMR, 13 C{ 1 H} NMR and 2D NMR techniques. Both complexes a re pentane soluble and the complexes could not be separated in bulk; however, yellow single crystals of 18A were obtained by cooling an ether solution of the mixture at 35 C for 12 h. 18A : 1 H NMR (500 MHz, C 6 D 5 CD 3 (ppm)): 7.56 (2H, Ar H ), 7.55 (1H, Ar H ), 7.31 (2H, Ar H ), 7.27 (2H, Ar H ), 7.19 (2H, Ar H ), 7.16 (2H, Ar H ), 7.04 (2H, Ar H ), 6.79 (2H, Ar H ), 6.77 (2H, Ar H ), 6.77 (2H, Ar H ), 6.61 (1H, Ar H ), 6.31 (2H, Ar H ), 1.50 (s, 18H, C(C H 3 ) 3 ), 1.42 (s, 3H, C H 3 ), 0.93 (s, 9H, W CC(C H 3 ) 3 ). 13 C{ 1 H}NMR ( 125.6 MHz, C 6 D 5 CD 3 C t Bu), 205.0 (s, W C Ph), 200.0 (s, W C Ph), 168.0 (s, C aromatic), 155.7 (s, C aromatic), 145.6 (s, C aromatic), 141.6 (s, C aromatic), 138.7 (s, C aromatic), 134.9 (s, C aromatic) 134.5 (s, C aromatic), 129.8 (s, C aromatic ) 129.2 (s, C aromatic), 128.6 (s, C aromatic)

PAGE 122

122 128.1 (s, C aromatic), 127.8 (s, C aromatic), 126.2 (s, C aromatic), 126.2 (s, C aromatic), 126.1 (s, C aromatic), 126.0 (s, C aromatic), 119.2 (s, C aromatic), 115.3 (s, C aromatic), 111.3 (s, C ar omatic), 105.0 (s, C aromatic), 46.6 (s, W C C (CH 3 ) 3 ), 35.8 (s, W CC( C H 3 ) 3 ), 35.3 (s, C (CH 3 ) 3 ), 30.0 (s, C( C H 3 ) 3 ), 25.1 (s, W CC C H 3 ). 18B : 1 H NMR (500 MHz, C 6 D 5 CD 3 (ppm)): 7.78 (1H, Ar H ), 7.58 (2H, Ar H ), 7.48 (2H, Ar H ), 7.33 (1H, Ar H ), 7.31 (2H, Ar H ), 7.28 (2H, Ar H ), 7.22 (2H, Ar H ), 7.21 (2H, Ar H ), 7.15 (2H, Ar H ), 7.06 (1H, Ar H ), 7.00 (1H, Ar H ), 6.84 (2H, Ar H ), 1.94 (s, 3H, C H 3 ), 1.44 (s, 18H, C(C H 3 ) 3 ), 0.96 (s, 9H, W CC(C H 3 ) 3 ). 13 C{ 1 H}NMR (125.6 MHz, C 6 D 5 CD 3 309.9 (s, W= C t Bu), 208.1 (s, W C Ph), 198.5 (s, W C Ph), 168.3 (s, C aromatic), 157.0 (s, C aromatic), 144.1 (s, C aromatic), 141.5 (s, C aromatic), 138.6 (s, C aromatic) 134.5 (s, C aromatic), 133.8 (s, C aromatic), 129.4 (s, C aromatic), 128.6 (s, C aromatic), 128.4 (s, C, aromatic), 128.1 (s, C aromatic), 128.1 (s, C aromatic), 127.7 (s, C aromatic), 127.5 (s, C aromatic), 126.9 (s, C, aromatic), 126.2 (s, C aromatic), 119. 2 (s, C aromatic), 116.0 (s, C aromatic), 114.5 (s, C aromatic), 107.7 (s, C aromatic), 46.7 (s, W C C (CH 3 ) 3 ), 35.8 (s, W CC( C H 3 ) 3 ), 35.3 (s, C (CH 3 ) 3 ), 30.0 (s, C( C H 3 ) 3 ), 21.7 (s, W CC C H 3 ). 4.4.8 Synthesis of [O 2 C(PhC=)W( 2 CO 2 CH 3 )] ( 19 ) In a nitrogen filled glove box, a glass vial was charged with [ t BuOCO] WC ( t Bu)(THF) 2 ( 1 5 ) (0.100 mg, 0.130 mmol) in toluene (10 mL) and cooled to 35 C Methyl propiolate (12.1 L, 0.136 mmol) was added with stirring. The solvent wa s removed in vacuo. Pentane (10 mL) was added resulting in a yellow precipit ate and an orange supernatant. The yellow solid was isolated via filtration and then was washed with additional cold pentane (5 mL) to yield complex 19 Single crystals were obtain ed

PAGE 123

123 by cooling an ether solution of 19 at 35 C for 12 h Yield (190 mg, 45%). 1 H NMR (500 MHz, C 6 D 5 CD 3 (ppm)): 11.29 (s, 1 H, W C H ), 7.42 (d, 2 H, Ar H ), 7.30 (d, 2 H, Ar H ), 7.25 (d 2H, Ar H ), 7.21 (t, 1 H, Ar H ), 6.79 (t, 2 H, Ar H ), 3.67 (s, 3 H, O C H 3 ), 1.31 (s, 9 H, W CC H 3 ), 1.31 (s, 18 H, C(C H 3 ) 3 ). 13 C{ 1 H}NMR (125.6 MHz, C 6 D 5 CD 3 m)): 274 .0 (s, W= C C t B u), 191.2 (s, W C H), 188.9 (s, W C H), 176.0 (s, C =O), 168.3 (s, C aromatic), 154.4 (s, C aromatic), 137.9 (s, C aromatic), 133.6 (s, C aromatic), 130.9 (s, C aromatic), 129.3 (s, C aromatic), 128.0 (s, C aromatic), 1 26.3 (s, C aromatic), 123.9 (s, C aromatic) 119.3 (s, C aromatic), 51.1 (s, O C H 3 ), 46.7 (s, W C C (CH 3 ) 3 ), 34.7 (s, C (CH 3 ) 3 ), 30.4 (s, W CC(C H 3 ) 3 ), 30.4 (s, C( C H 3 ) 3 ), 4.4.9 Polymerization of Alkynes using [ t t Bu)(THF) 2 (15), [O 2 C( t BuC=)W( 2 t Bu) and [O 2 C(PhC=)W( 2 t Bu)] (16 Ph). In a nitrogen filled glove a stock solution of either 15 16 t Bu or 16 Ph in toluene (2.0 mL). The solu tion was allowed to stir a t room temperature for 60 min. The reaction mixture was removed from the glovebox, and the polymeric material was precipitated by dropwise addition to stirring methanol (20 mL). The polymeric material was collected by filtration a nd dried in va cuo for 2 h prior to weighing. The dried polymer (10 mg) was dissolved in HPLC grade THF containing no preservative (10 mL), filtered through a 0.45 micro n filter, and analyzed by GPC. A 1 H NMR in CDCl 3 and an IR spectrum using a KBR plate we re acquired for the polymer. The above procedure was adopted for polymerization runs involving all reported monomers.

PAGE 124

124 Figure 4 1 Precatalyst [ t 3 ) 3 )(THF) 2 ( 15 ). Figure 4 2 Full synthetic scheme for the synthesis of [ t t Bu)(THF) 2 ( 15 ). Figure 4 3. Proposed ring expansion polymerization of alkynes.

PAGE 125

125 Figure 4 4. Illustration of how trianionic pincer ligands can facilitate coordination of a second alkyne. Figure 4 5. New tretranionic pincer type ligand [O 2 C(R)C=] 4 R = Ph, t Bu. Figure 4 6 Synthesis of 16 t Bu and 16 Ph supported by the tetraanionic pincer type ligand [O 2 C(RC=)W( 2 t Bu)] (R = t Bu, Ph).

PAGE 126

126 Figure 4 7. Molecular structure of 16 Ph with ellipsoids present at 50% probability. All hydrogen atoms and the methyl groups o n C28 are removed for clarity. 27 =

PAGE 127

127 Table 4 1. X ray crystallogr aphic structure parameters and refinement data. Figure 4 8. Canonical forms of 2 H 16 Ph 17 Ph 18 A emp formula C 45 H 56 O 3.5 W C 48 H 62 O 4 W C 48 H 50 O 2 W formula weight 836.75 886.83 879.79 crystal system Triclinic Triclinic Monoclinic Space Group P 1 P2 1 /c dimensions(mm) 0.19/0.12/0.04 0.17 /0.13/0.05 0.12/0.09/0.05 a () 9.4199(4) 12.5307(3) 9.6683(5) b () 12.1830(5) 18.2485(4) 40.736(2) c () 17.6797(7) 19.5913(4) 21.0306(13) (deg) 93.621(2) 91.056(1) 90 (deg) 100.409(2) 93.582(1) 97.047(1) (deg) 102.237(2) 109.527(1) 90 volume ( 3 ) 1939.34(14) 4210.28(16) 8220.3(8) Z () 2 4 8 abs coeff mm 1 3.018 2.786 2.851 F (000) 856 1824 3592 D calcd (g/cm 3 ) 1.433 1.399 1.422 0.71073 0.71073 0.71073 temperature (K) 100(2) 100(2) 100(2) range (deg) 1.72 to 27.50 1.73 t o 27.50 1.00 to 27.50 refl collected 53616 65439 73336 indep refl [ R int ] 8897 [0.0476] 19344 [0.0665] 18795 [0.0534] data/rest/param 8897/0/456 19344/0/948 18795 / 0 / 986 final R 1 indices > R1 = 0.0262, wR2 R1 = 0.0377, wR2 R1 = 0.0361, wR2 ] 0.0639 [8071] 0.0748[1460] 0.0577[12987] R indices R1 = 0.0302, R1 = 0.0576, wR2 R1 = 0.0700, wR2 (all data) wR2 = 0.0655 wR2 = 0.0828 wR2 = 0.0694 diff peak/hole 2.205/ 2.364 1.024/ 0.926 1.435/ 1.767 goodness of fit 1.050 1.023 0.956

PAGE 128

128 Figure 4 9. Equilibrium reaction between 16 t Bu (kinetic product) and 16 Ph (thermodynamic product) at 85 C, toluene d 8 Figure 4 10. Concentration of conversio n of 16 t Bu into 16 Ph vs time.

PAGE 129

129 Figure 4 11 Integrated rate law for a reversible first order reaction for the conversion of 16 t Bu into 16 Ph vs time (h). Slope (m) = (k 1 + k 1 ) = 4.06(1) x10 6 s 1 Figure 4 12 Plots of the ln[ 16 t Bu ] ( red ) and ln [ 16 Ph ] ( blue ) vs time.

PAGE 130

130 Figure 4 13 Synthesis of 17 t Bu and 17 Ph supported by the tetraanionic pincer type ligand [O 2 C(RC=)W( 2 t Bu)] (R = t Bu, Ph). Figure 4 14 Molecular structure of 17 Ph with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. Methyl groups attached to C28 are disordered over two positions and are removed for clarity. Sele cted bond 39.0(4),

PAGE 131

131 Figure 4 15 Catalytic TON determined by quantitative yield (mg) of PPA vs. time (min) for 15 16 t Bu and 16 Ph All data points completed in triplicate (average values shown). Table 4 2. Ace tylene polymerization results using 15 a Substrate % Yield TON M n b /10 3 M w /M n b 1 E thynyl 4 methoxybenzene 91 4540 17.4 2.24 Phenylacetylene 99 4994 10.6 3.17 1 E th y nyl 4 fluorobenzene 70 3497 11.1 3.16 1 E th y nyl 3,5 bis(trifluoromethyl)benzene 10 525 7. 5 1.46 1 Ethynyl 4 nitrobenzene 0 1 D ecyne 96 4810 130.7 1.27 3,3 D imethyl 1 butyne c 95 950 2.1 1.56 Methyl propiolate 0 T rimethylsilylacetylene c,d 66 672 a 15 1 h at 25 C. b Determined by GPC. c 15 ( d M w M n and M w /M n could not be determined due to polymer insolubility in THF.

PAGE 132

132 Table 4 3. Acetylene polymerization results using 16 t Bu a Substrate % Yield TON M n b /10 3 M w /M n b Monosubstituted Acetylenes 1 E thynyl 4 methoxybenzene 94 4691 17.4 2.18 P henylacetylene 99 4994 16. 2 3.49 1 E th y nyl 4 fluorobenzene 64 3205 10.8 3.00 1 E th y nyl 3,5 bis(trifluoromethyl)benzene 9 462 31.6 1.96 1 Ethynyl 4 nitrobenzene 0 1 D ecyne 97 4846 119.4 1.37 3,3 D imethyl 1 butyne c 97 974 2.1 1.54 Methyl propiolate 0 T rimethy silyl l acetylene c,d 54 540 Disubstituted Acetylene 1 P henyl 1 propyne e 78 77 23.2 1.43 a 16 t Bu for 1 h at 25 C. b Determined by GPC. c 16 t Bu d to d M w M n and M w /M n could not be determined due to polymer insolubility in THF. e 16 t Bu ) h at 75 C. Figure 4 16 allacyclopentadiene isomers 18A and 18B

PAGE 133

133 Figure 4 17 Molecular structure of 18 A with ellipsoids presented at 50% probability and hydro gen atoms removed fo r clarity. Selected bond lengths () and angles 133.91(17),

PAGE 134

134 Figure 4 18 Two possible routes to the overall formal reductive alkylidyne migratory insertion. A : direct insertion, B : metallacyclobutadiene intermediate. Figure 4 1 9 Truncated X ray structural data ( 18A ) highlighting the meridional coordination of the tetraanionic pincer type ligand [O 2 C( t BuC=)] 4

PAGE 135

135 Table 4 4. Optimized polymerization results using 16 t Bu a Substrate Sub:Cat Loading % Yield Time (min) TON Act ivity (g PA /mol/hr) Phenylacetylene 25,0 00 : 1 69 60 17,233 1,760,000 Phenylacetylene 10,0 00 : 1 92 10 9,204 5,640,000 1 Decyne 10,000 : 1 96 10 9,620 7,980,000 a 1 6 t Bu for 1 h at 25 C. Figure 4 20 Proposed mechanism for polymer chain growth

PAGE 136

136 Figure 4 21 Molecular structure of 19 with ellipsoids presen ted at 50% probability and hydrogen atoms removed for clarity. Selected bond le ngths () and angles = C27 = = 148.74(5 ), C31 87.93(7), C30 = 37.66(7 ), C30

PAGE 137

137 Figure 4 22. A ddition of HCCPh( p NO 2 ) to 1 5 to form a tungsten alkylidene ( 20 ). This structure is not fully elucidated. Figure 4 23. Catalytic activation of 15 by HCCPh( p NO 2 ) and heating of 15 to form 20

PAGE 138

138 APPENDIX NMR, IR, UV VIS, EPR, MS, GPC, X RAY DATA A.1 NMR Data Figure A 1. 1 H NMR spectrum of {[2,6 i PrNCHN]Zn} 2 ( 4 ) in benzene d 6

PAGE 139

139 Figure A 2. 13 C{ 1 H} NMR spectrum of {[2,6 i PrNCHN] Zn} 2 ( 4 ) in benzene d 6

PAGE 140

140 Figure A 3. 1 H NMR spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) obtained in benzene d 6

PAGE 141

141 Figure A 4. 1 H NMR spectrum of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) obtained in benzene d 6

PAGE 142

142 Figure A 5. 1 H NMR spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ) obtained in benzene d 6

PAGE 143

143 Figure A 6. 1 H NMR spectrum of [2,6 i PrNCN]Cr V (O)( THF) ( 8 ) obtained in benzene d 6

PAGE 144

144 Figure A 7. 1 H NMR spectrum of [2,6 i PrNCMeN]H 2 ( 9 ) obtained in benzene d 6

PAGE 145

145 Figure A 8. 13 C NMR spectru m of [2,6 i PrNCMeN]H 2 ( 9 ) obtained in benzene d 6

PAGE 146

146 Figure A 9. 1 H NMR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ) obtained in benzene d 6

PAGE 147

147 Figure A 10. 13 C NMR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ) obtained in benzene d 6

PAGE 148

148 Figure A 11. 1 H NMR spectrum of 16 t Bu in C 6 D 6 at 25 C.

PAGE 149

149 Figure A 12. 13 C NMR spectrum of 16 t Bu in C 6 D 6 at 25 C, expansion of the aliphatic region.

PAGE 150

150 Figure A 13. 13 C NMR spectrum of 16 t Bu in C 6 D 6 at 25 C, expansion of the aromatic region.

PAGE 151

151 Figure A 14. 1 H NMR spectrum of 16 Ph in C 6 D 6 at 25 C.

PAGE 152

152 Figure A 15. 13 C NMR spectrum of 16 Ph in C 6 D 6 at 25 C, expansion of the aliphatic region.

PAGE 153

153 Figure A 16. 13 C NMR spectrum of 16 Ph in C 6 D 6 at 25 C, expansion of the aromatic region

PAGE 154

154 Table A 1. Assignment of 1 H and 13 C chemical shifts for 16 t Bu and 16 Ph in toluene d 8 at 25 C. Compound 16 t Bu 16 Ph Position d 1 H (ppm) (ppm) d 13 C (ppm) d 1 H (ppm) (ppm) d 13 C (ppm) 1,18 167.0 168.6 2,17 137.7 137.2 3,16 7.20 125.9 7.12 125.9 4,15 6.78 119.0 6.67 119.2 5,14 7.31 128.1 7.25 128.1 6,13 130.9 130.6 7,11 153.2 152.1 8,10 7.4 6 129.1 7.48 130.1 9 7.30 132.7 7.33 132.5 12 126.4 125.9 19,23 34.7 34.9 20 22, 24 26 1.14 30.2 1.18 30.4 27 200.3 213.1 28 46.5 35.3 29 31 0.93 36.2 1.68 30.7 32 11.95 188.1 11.56 187.9 33 270.0 252.6 34 139.8 144.9 35, 39 7.94 130.6 6.74 131.1 36,38 7.41 128.5 6.93 126.7 37 7.20 128.7 6.52 126.4

PAGE 155

155 Figure A 17. 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 Figure A 18. 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion of the aliphatic region.

PAGE 156

156 Figure A 19. 1 H spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion of the aromatic region. Figure A 20. 1 H 13 C gHSQC spectrum of a mixtur e of 16 t Bu and 16 Ph in toluene d 8

PAGE 157

157 Figur e A 21. 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. Figure A 22. 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion.

PAGE 158

158 Figure A 23. 1 H 13 C gH MBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion. Figure A 24. 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion.

PAGE 159

159 Figure A 25. 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 e xpansion. Figure A 26. 1 H 13 C gHMBC spectrum of a mixture of 16 t Bu and 16 Ph in toluene d 8 expansion.

PAGE 160

160 Figure A 27. 1 H NMR spectrum of 17 t Bu in C 6 D 6 at 25 C.

PAGE 161

161 Figure A 28. 1 H NMR spectrum of 17 Ph in C 6 D 6 at 25 C.

PAGE 162

162 Figure A 29. 13 C NMR spectrum of 17 Ph in C 6 D 6 at 25 C, expansion of the aliphatic region.

PAGE 163

163 Figure A 30. 13 C NMR spectrum of 17 Ph in C 6 D 6 at 25 C, expansion of the aromatic region.

PAGE 164

164 Table A 2. Assignment of 1 H and 13 C chemical shifts for 17 t Bu and 17 Ph in toluene d 8 at 25 C. Compound 17 Ph 17 t Bu Position d 1 H (ppm) (ppm) d 13 C (ppm) d 1 H (ppm) (ppm) d 13 C (ppm) 1,18 167.7 168.6 2,17 137.3 137.4 3,16 7. 23 125.7 7.21 125.8 4,15 6.76 118.9 6.79 118.7 5,14 7.23 128.2 7.31 128.0 6,13 130.9 130.8 7,11 151.6 154.8 8,10 7.42 129.8 7.45 128.9 9 7.27 132.1 7.30 132.9 12 127.7 126.7 19,23 34.8 34.5 20 22, 24 26 1.26 30.1 1.20 29.8 27 20 8.7 200.2 28 40.7 44.5 29 31 1.65 30.9 0.87 34.1 32 196.9 196.9 33 251.7 267.3 34 148.9 141.2 35,39 6.41 129.6 7.81 128.5 36,38 6.88 127.0 7.42 128.3 37 6.64 125.7 7.18 127.3 40 2.82 19.3 3.34 23.5

PAGE 165

165 Figure A 31. 1 H spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 Figure A 32. 1 H spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion of the aliphatic region.

PAGE 166

166 Figure A 33. 1 H spectrum of mixt ure of 17 t Bu and 17 Ph in toluene d 8 expansion of the aromatic region. Figure A 34. 1 H 13 C gHSQC spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion of the aliphatic region.

PAGE 167

167 Figure A 35. 1 H 13 C gHSQC spectrum of mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. Figure A 36. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8

PAGE 168

168 Figure A 37. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. Figure A 38. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion.

PAGE 169

169 Figure A 39. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. Figure A 40. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion.

PAGE 170

170 Figur e A 41. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. Figure A 42. 1 H 13 C gHMBC spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion.

PAGE 171

171 Figure A 43. 1 H 13 C gHMBC spectrum ( optimized for 4 Hz) of a mixtur e of 17 t Bu and 17 Ph in toluene d 8 expansion Figure A 44. ROESY spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion.

PAGE 172

172 Figure A 45. ROESY spectrum of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion. Figure A 46. ROESY spectr um of a mixture of 17 t Bu and 17 Ph in toluene d 8 expansion.

PAGE 173

173 Table A 3. Assignment of 1 H and 13 C chemical shifts for 18A and 18B in toluene d 8 at 25 C. Compound 18A 18B Position d 1 H (ppm) d 13 C (ppm) d 1 H (ppm) d 13 C (ppm) 1,18 168.0 168.3 2 ,17 138.7 138.6 3,16 7.31 126.0 7.31 126.2 4,15 6.79 119.2 6.84 119.2 5,14 7.19 129.2 7.28 128.1 6,13 129.8 129.4 7,11 155.7 157.0 8,10 7.16 134.5 7.58 133.8 9 6.77 134.9 7.33 134.5 12 105.0 107.7 19,23 35.3 35.3 20 22, 24 26 1.50 30.0 1.44 30.0 27 310.0 309.9 28 46.6 46.7 29 31 0.93 35.8 0.96 35.8 32 205.0 208.1 33 111.3 116.0 34 7.55 115.3 7.78 114.5 35 200.0 198.5 36 141.6 144.1 37,41 7.56 128.6 7.48 128.6 38,40 7.27 128.1 7.21 128.1 39 7 .04 127.8 7.00 127.7 42 145.6 141.5 43,47 6.31 126.2 7.22 127.5 44,46 6.77 126.2 7.15 128.4 45 6.61 126.1 7.06 126.9 48 1.42 25.1 1.94 21.7

PAGE 174

174 Figure A 47. 1 H 1 H gDQF COS Y spectrum of mixture of 18A and 18B in toluene d 8 Figure A 48. 1 H 1 3 C gHSQCAD spectrum of mixture of 18A and 18B in toluene d 8

PAGE 175

175 Figure A 49. 1 H 13 C gHSQCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. Figure A 50. 1 H 13 C gHSQCAD sp ectrum of mixture of 18A and 18B in toluene d 8 expansion.

PAGE 176

176 Figure A 51. 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 Figure A 52. 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion.

PAGE 177

177 Figure A 53. 1 H 13 C g HMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion. Figure A 54. 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion.

PAGE 178

178 Figure A 55. 1 H 13 C gHMBCAD spectrum of mixture of 18A and 18B in toluene d 8 expansion.

PAGE 179

179 Figure A 56. 1 H NMR spectrum of 19 in toluene d 8

PAGE 180

180 Table A 4. Assignment of 1 H and 13 C chemical shifts for 19 in toluene d 8 at 25 C. Compound 19 Position d 1 H (ppm) (ppm) d 13 C (ppm) 1,18 168.3 2,17 1 37.9 3,16 7.25 12 6.3 4,15 6.79 119.3 5,14 7.30 128.0 6,13 130.9 7,11 154.4 8,10 7.42 129.3 9 7.21 133.6 12 123.9 19,23 34.7 20 22, 24 26 1.31 30.4 27 191.2 28 176.0 29 3.67 51.1 3 0 11. 29 188.9 31 274.0 32 46.7 33 35 1.31 30 .4

PAGE 181

181 Figure A 57. 1 H NMR spectrum of 19 in benzene d 6 Figure A 58. 1 H NMR spectrum of 19 in benzene d 6 expansion of the aliphatic region.

PAGE 182

182 Figure A 59. 1 H NMR spectrum of 19 in benzene d 6 expansion o f the aromatic region. Figure A 60. 1 H 13 C gHSQC spectrum of compound 19 in benzene d 6

PAGE 183

183 Figure A 61. 1 H 13 C gHMBC spectrum of 19 in benzene d 6 Figure A 62. 1 H 13 C gHMBC spectrum of 19 in benzene d 6 expansion.

PAGE 184

184 Figure A 63. 1 H 1 H ROESY spectru m of 19 in benzene d 6 Figure A 64. 1 H 1 H ROESY spectrum of 19 in benzene d 6 expansion.

PAGE 185

185 Figure A 65 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 Figure A 66 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of the aromatic region.

PAGE 186

186 Figu re A 67 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 Figure A 68 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of aliphatic region.

PAGE 187

187 Figure A 69 1 H 13 C gHMBC spectr um of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of aliphatic region. Figure A 70 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in toluene d 8 expansion of aliphatic region.

PAGE 188

188 Figure A 71 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 Figure A 72 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion of aromatic region.

PAGE 189

189 Figure A 73 1 H NMR spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion of aliphatic region. Figure A 74 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12

PAGE 190

190 Figure A 75 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. Figure A 76 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexa ne d 12 expansion.

PAGE 191

191 Figure A 77 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion. Figure A 78 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in cyclohexane d 12 expansion.

PAGE 192

192 Figure A 79 1 H spectrum of 15 in pen tafluoropyridine Figure A 80 1 H spectrum of 15 in pentafluoropyridine, expansion of aromatic region.

PAGE 193

193 Figur e A 81 1 H 13 C gHMBC spectrum of 15 in pentafluoropyridine. Figur e A 82 1 H 13 C gHMBC spectrum of 15 in pentafluoropyridine, expansion of aro matic region.

PAGE 194

194 Figure A 83 1 H spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine. Figure A 84 1 H spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine, expansion of aromatic region.

PAGE 195

195 Figur e A 85 1 H 13 C gHMBC spectrum of 15 + 4 n itrophenylacetylene in pentafluoropyridine. Figur e A 86 1 H 13 C gHMBC spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine, expansion of aromatic region.

PAGE 196

196 Figur e A 87 1 H 13 C gHSQC spectrum of 15 + 4 nitrophenylacetylene in pentafluoropyridine expansion of aromatic region.

PAGE 197

1 97 Figure A 88 1 H NMR of PPA derived from the phenylacetylene monomer. Figure A 89 1 H NMR of PPA derived from the 1 ethynyl 4 fluorobenzene monomer.

PAGE 198

198 Figure A 90 1 H NMR of PPA derived from the 1 ethynyl 4 methoxybenzene monomer.

PAGE 199

199 A.2 IR DATA Figure A 91 IR spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ). Figure A 92 IR spectrum of [2,6 i PrNCN]CrMe IV (THF) ( 6 ).

PAGE 200

200 Figure A 93 IR spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ). Figure A 94 IR spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ).

PAGE 201

201 Figure A 95 IR spectrum of [2,6 i PrNCMeN]H 2 ( 9 ). Figure A 96 IR spectrum of [2,6 i PrNCN]H 2 Br ( 10 ).

PAGE 202

202 Figure A 97 IR spectrum of poly( phenylacetyle ne ). Figure A 98 IR spectrum of poly( fluorophenylacetylene ).

PAGE 203

203 Figure A 99 IR spectrum of poly( methoxyphenylacetylene ).

PAGE 204

204 A.3 UV Vis Data Figure A 100 UV vis spectrum of [2,6 i PrNCN]Cr III (THF) 3 ( 5 ) in benzene.

PAGE 205

205 Figure A 101 UV vis spectrum of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) in pentane.

PAGE 206

206 Figure A 102 UV vis spectrum of [2,6 i PrNHCN]Cr II (THF) 2 ( 7 ) in pentane.

PAGE 207

207 Figure A 103 UV Vis spectrum of [2,6 i PrNCN]Cr V (O)(THF) ( 8 ) in benzene.

PAGE 208

208 A.4 EPR DATA Figure A 104 EPR spectrum of [2,6 i P rNCN]Cr V (O)(THF ) ( 8 ) ( 2.5 mM solution, toluene) at T = 20 K.

PAGE 209

209 A.5 MS DATA Figure A 105 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with D 2 O.

PAGE 210

210 Figure A 106 ESI TOF mass spectra of [2,6 i PrNCN]Cr IV Me(THF) ( 6 ) heated for 48 h at 85 C then quenched with H 2 O.

PAGE 211

211 A.6 GPC DATA Table A 5. RAD high temperature GPC results summary for ethylene polymerization runs using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ). Run Sample ID M w M n PDI 7 27b 5 87,706 22,077 26.62 8 32b 421,153 12,962 32.49 9 17b 302,580 11,937 25.35 10 34b 274,009 11,580 23.66 13 16b 414,350 10,213 40.57 14 18b 284,567 6,681 42.60 15 19b 211,441 3,545 59.65 16 20b 161,307 3,111 51.86 18 21b 513,585 21,530 23.85 19 22b 3 80,352 15,603 24.38 20 25b 302,627 16,758 18.06 21 23b 353,583 21,044 16.80 22 26b 341,107 19,589 17.41 23 24b 280,550 16,499 17.00 24 35b 277,806 11,405 24.36 Parameters Solvent: TCB Temp: 150 C Flow Rate: 2.00 mL/min Detector: PolyChar IR4 C olumns: (2) PL 10 um Mixed B (10x300mm) Injection Vol.: Sample Conc.: 1 mg/mL Dissolution: 90 minutes at 165 C. 30mg/mL concentrated mother, then dilluted to 1mg/mL prior to running.

PAGE 212

212 Figure A 107 GPC chromatogram fo r ethylene polymerization runs using [2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 213

213 Figure A 108 DSC curve for ethylene polymerization run 7 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 214

214 Figure A 109 DSC curve for ethylene polymerization run 8 using [ 2,6 i PrNCN]Cr IV Me (THF) ( 6 ).

PAGE 215

215 Figure A 110 DSC curve for ethylene polymerization run 9 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 216

216 Figure A 111 DSC curve for ethylene polymerization run 10 using [ 2,6 i PrNCN] Cr IV Me(THF) ( 6 ).

PAGE 217

217 Figure A 112 DSC curve for ethylene polymerizati on run 13 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 218

218 Figure A 113 DSC curve for ethylene polymerization run 14 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 219

219 Figure A 114 DSC curve for ethylene polymerization run 15 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 220

220 Figure A 115 DSC curve for ethylene polymerization run 16 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 221

221 Figure A 116 DSC curve for ethylene polymerization run 18 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 222

222 Figure A 117 DSC curve for ethylene polymerization run 19 using [ 2,6 i PrNCN ]Cr IV Me(THF) ( 6 ).

PAGE 223

223 Figure A 118 DSC curve for ethylene polymerization run 20 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 224

224 Figure A 119 DSC curve for ethylene polymerization run 21 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 225

225 Figure A 120 DSC curve for ethylene poly merization run 22 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 226

226 Figure A 121 DSC curve for ethylene polymerization run 23 using [ 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 227

227 Figure A 122 DSC curve for ethylene polymerization run 24 using 2,6 i PrNCN]Cr IV Me(THF) ( 6 ).

PAGE 228

228 Figure A 123 GPC chromatogram for polymer of phenylacetylene using 15 Figure A 124 GPC chromatogram for polymer of 1 ethynyl 4 methoxybenzene using 15

PAGE 229

229 Figure A 125 GPC chromatogram for polymer of 1 ethynyl 4 fluorobenzene using 15 Figure A 126 G PC chromatogram for polymer of 1 ethynyl 3,5 bis(trifluoromethyl)benzene using 15

PAGE 230

230 Figure A 127 GPC chromatogram for polymer of 1 decyne using 15 Figure A 128 GPC chromatogram for polymer of 3,3 dimethyl 1 butyne using 15

PAGE 231

231 Figure A 129 GPC ch romatogram for polymer of phenylacetylene using 16 t Bu Figure A 130 GPC chromatogram for polymer of 1 ethynyl 4 methoxybenzene using 16 t Bu

PAGE 232

232 Figure A 131 GPC chromatogram for polymer of 1 ethynyl 4 fluorobenzene using 16 t Bu Figure A 132 GPC chromatogram for polymer of 1 ethynyl 3,5 bis(trifluoromethyl)benzene using 16 t Bu

PAGE 233

233 Figure A 133 GPC chromatogram for polymer of 1 decyne using 16 t Bu Figure A 134 GPC chromatogram for polymer of 3,3 dimethyl 1 butyne using 16 t Bu

PAGE 234

234 A.7 X Ray Crystall ographic Data Figure A 135 Molecular structure of 4 with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. X ray experimental details for 4 : Data were collected at 173 K on a Siemens SMART PLATFORM equipped with A CCD ar 0.7107 3 ). Cell parameters were refined using up to 8192 reflections. A full sphere of s can method (0.3 frame width). The first 50 frames were re measured at the end of data collection to monitor instrument and crystal stability (maxim um correction on I was < 1 %). Absorption corrections by integration were applied based on measured indexed crystal faces. The structure was solved by the Di rect Methods in SHELXTL6, and refined us ing full matrix least squares. The non H atoms were treated anisotropically, whereas the

PAGE 235

235 hydrogen atoms were calculated in ideal positions and were riding on their respective carbon atoms. The asymmetric unit consist s of a dimer in general position and two half dimers located on inversion centers. The dimers are chemically equivalent but cry stallographically independent. A total of 1293 parameters were refined in the final cycle of refinement using 20900 reflections w ith I > 2 (I) to yield R 1 and wR 2 of 3.78% and 9.12%, respectively. Refinement was done using F 2

PAGE 236

236 Table A 6. Crystal data, structure solution and refinement for 4 identification code Mcg1 empirical formula C 64 H 84 N 4 Zn 2 formula weight 1040 .09 T (K) 100(2) 0.71073 crystal system Monoclinic space group P2 1 /c a () 43.169(7) b () 14.132(2) c () 19.314(3) (deg) 90 (deg) 90.577(3) (deg) 90 V ( 3 ) 11782(3) Z 8 calcd (Mg mm 3 ) 1.173 crystal size (mm 3 ) 0.31 x 0.26 x 0.20 abs coeff (mm 1 ) 0.855 F (000) 4448 range for data collection 0.94 to 27.50 limiting indices h k l no. of reflns collcd 84071 no of ind reflns ( R int ) 26885 (0.0361) completeness to = 27.50 99.4 % absorption corr None refinement method Full matrix least squares on F 2 data / restraints / parameters 26885/ 0 /1293 R 1, a wR 2 b [I > 2 ] 0.03 78, 0.0.0912[20900] R 1, a wR 2 b (all data) 0.0553, 0.1000 GOF c on F 2 1.015 largest diff. peak and hole 0.909 and 0.544 e. 3 a R 1 = || F o | F c ||/ | F o |. b w R 2 = ( ( w ( F o 2 F c 2 ) 2 )/ ( w ( F o 2 ) 2 )) 1/2 c GOF = ( w ( F o 2 F c 2 ) 2 /( n p )) 1/2 where n is the number of data and p is the number of parameters refined.

PAGE 237

237 Table A 7. Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 4 U(eq) is defi ned as one third of the trace of the orthogonalized Uij tensor. Atom x y z U(eq) Zn1A 7163(1) 3354(1) 6780(1) 17(1) Zn2A 7908(1) 6662(1) 8256(1) 17(1) N1A 6882(1) 4175(1) 6422(1) 19(1) N2A 7653(1) 7622(1) 7996(1) 19(1) N3A 7376(1) 2302(1) 7031(1) 19(1) N 4A 8192(1) 5897(1) 8671(1) 18(1) C1A 6924(1) 5151(1) 6207(1) 24(1) C2A 7240(1) 5541(1) 6396(1) 19(1) C3A 7514(1) 5073(1) 6221(1) 23(1) C4A 7800(1) 5465(1) 6391(1) 27(1) C5A 7817(1) 6344(1) 6719(1) 24(1) C6A 7547(1) 6827(1) 6897(1) 19(1) C7A 7264(1) 6402(1) 6740(1) 20(1) C8A 7560(1) 7767(1) 7270(1) 21(1) C9A 6572(1) 3823(1) 6348(1) 17(1) C10A 6365(1) 3907(1) 6905(1) 20(1) C11A 6070(1) 3510(1) 6839(1) 25(1) C12A 5980(1) 3047(1) 6237(1) 28(1) C13A 6182(1) 2980(1) 5688(1) 27(1) C14A 6480(1) 3365(1) 5729(1) 22(1 ) C15A 6457(1) 4390(1) 7581(1) 23(1) C16A 6258(1) 5267(2) 7721(1) 38(1) C17A 6443(1) 3699(2) 8189(1) 31(1) C18A 6701(1) 3253(1) 5125(1) 28(1) C19A 6565(1) 3630(2) 4444(1) 52(1) C20A 6804(1) 2222(2) 5044(1) 36(1) C21A 7614(1) 8426(1) 8439(1) 19(1) C22A 7372 (1) 8416(1) 8929(1) 25(1) C23A 7326(1) 9213(2) 9339(1) 32(1) C24A 7511(1) 10006(2) 9282(1) 31(1) C25A 7756(1) 9998(1) 8825(1) 26(1) C26A 7814(1) 9213(1) 8405(1) 20(1) C27A 7168(1) 7545(2) 9020(1) 38(1) C28A 6895(1) 7559(2) 8537(1) 59(1) C29A 7060(1) 7405(2 ) 9765(1) 57(1) C30A 8102(1) 9210(1) 7951(1) 20(1) C31A 8394(1) 9146(1) 8405(1) 28(1) C32A 8115(1) 10072(1) 7475(1) 27(1) C33A 7565(1) 2214(1) 7654(1) 24(1) C34A 7576(1) 3134(1) 8054(1) 20(1) C35A 7307(1) 3518(1) 8340(1) 24(1)

PAGE 238

238 Table A 7. Continued Atom x y z U(eq) C36A 7321(1) 4361(1) 8708(1) 25(1) C37A 7602(1) 4816(1) 8818(1) 21(1) C38A 7875(1) 4443(1) 8544(1) 19(1) C39A 7854(1) 3617(1) 8147(1) 18(1) C40A 8189(1) 4869(1) 8701(1) 24(1) C41A 7362(1) 1458(1) 6618(1) 19(1) C42A 7134(1) 764(1) 6752(1) 22(1) C 43A 7128(1) 50(1) 6339(1) 29(1) C44A 7339(1) 184(1) 5812(1) 32(1) C45A 7562(1) 502(1) 5684(1) 28(1) C46A 7578(1) 1323(1) 6080(1) 22(1) C47A 6894(1) 886(1) 7318(1) 25(1) C48A 6574(1) 1091(2) 7008(1) 40(1) C49A 6883(1) 23(2) 7794(1) 38(1) C50A 7814(1) 2085 (1) 5900(1) 26(1) C51A 8140(1) 1687(2) 5797(1) 37(1) C52A 7704(1) 2620(2) 5251(1) 36(1) C53A 8466(1) 6315(1) 8959(1) 18(1) C54A 8473(1) 6559(1) 9669(1) 20(1) C55A 8739(1) 6974(1) 9942(1) 26(1) C56A 8994(1) 7143(1) 9533(1) 29(1) C57A 8988(1) 6911(1) 8838(1) 26(1) C58A 8727(1) 6483(1) 8540(1) 20(1) C59A 8187(1) 6427(1) 10118(1) 26(1) C60A 7996(1) 7339(2) 10124(1) 42(1) C61A 8266(1) 6116(2) 10856(1) 35(1) C62A 8723(1) 6227(1) 7772(1) 24(1) C63A 9013(1) 5674(2) 7559(1) 38(1) C64A 8684(1) 7109(2) 7323(1) 34(1)

PAGE 239

239 Table A 8. Bond lengths (in ) for 4 Bond Length Bond Length Zn1A N1A 1.8100(15) C10A C15A 1.522(3) Zn1A N3A 1.8119(15) C11A C12A 1.388(3) Zn2A N4A 1.8141(15) C12A C13A 1.384(3) Zn2A N2A 1.8161(15) C13A C14A 1.397(3) N1A C9A 1.434(2) C14A C 18A 1.524(3) N1A C1A 1.452(2) C15A C17A 1.529(3) N2A C21A 1.434(2) C15A C16A 1.535(3) N2A C8A 1.468(2) C18A C19A 1.530(3) N3A C41A 1.436(2) C18A C20A 1.532(3) N3A C33A 1.452(2) C21A C26A 1.410(2) N4A C53A 1.428(2) C21A C22A 1.415(3) N4A C40A 1.453(2) C22A C23A 1.393(3) C4A C5A 1.396(3) C22A C27A 1.526(3) C5A C6A 1.398(3) C23A C24A 1.383(3) C6A C7A 1.392(3) C24A C25A 1.386(3) C6A C8A 1.513(2) C25A C26A 1.398(3) C9A C10A 1.412(3) C26A C30A 1.530(2) C9A C14A 1.413(3) C27A C28A 1.496(4) C10A C11A 1.395(3) C27A C29A 1.529(3) C30A C32A 1.527(3) C46A C50A 1.526(3) C30A C31A 1.532(3) C47A C48A 1.526(3) C33A C34A 1.513(2) C47A C49A 1.529(3) C34A C39A 1.393(2) C50A C51A 1.532(3) C34A C35A 1.399(3) C50A C52A 1.5 36(3) C35A C36A 1.389(3) C53A C54A 1.414(3) C36A C37A 1.389(3) C53A C58A 1.415(2) C37A C38A 1.398(2) C54A C55A 1.389(3) C38A C39A 1.398(2) C54A C59A 1.525(3) C38A C40A 1.512(2) C55A C56A 1.382(3) C41A C42A 1.414(2) C56A C57A 1.382(3) C41 A C46A 1.416(3) C57A C58A 1.397(3) C42A C43A 1.400(3) C58A C62A 1.526(3) C42A C47A 1.526(3) C59A C61A 1.527(3) C43A C44A 1.385(3) C59A C60A 1.530(3) C44A C45A 1.391(3) C62A C64A 1.528(3) C45A C46A 1.389(3) C62A C63A 1.535(3)

PAGE 240

240 Table A 9. Bond angles (in deg) for 4 Bond Angle Bond Angle N1A Zn1A N3A 164.65(7) C3A C4A C5A 120.56(17) N4A Zn2A N2A 166.64(7) C4A C5A C6A 120.17(17) C9A N1A C1A 114.84(14) C7A C6A C5A 118.04(17) C9A N1A Zn1A 115.87(11) C7A C6A C8A 120.69(16) C1A N1A Zn1A 12 9.28(12) C5A C6A C8A 121.25(17) C21A N2A C8A 115.23(14) C2A C7A C6A 122.72(17) C21A N2A Zn2A 120.07(12) N2A C8A C6A 109.89(14) C8A N2A Zn2A 121.91(11) C10A C9A C14A 120.42(16) C41A N3A C33A 114.18(14) C10A C9A N1A 119.55(16) C41A N3A Zn1A 120.96(12) C 14A C9A N1A 119.98(16) C33A N3A Zn1A 124.84(12) C11A C10A C9A 118.79(17) C53A N4A C40A 113.97(14) C11A C10A C15A 119.32(17) C53A N4A Zn2A 118.48(11) C9A C10A C15A 121.86(16) C40A N4A Zn2A 127.33(12) C12A C11A C10A 120.98(18) N1A C1A C2A 113.04(15) C13 A C12A C11A 120.03(18) C7A C2A C3A 118.21(17) C12A C13A C14A 121.10(19) C7A C2A C1A 119.64(16) C13A C14A C9A 118.66(17) C3A C2A C1A 122.13(17) C13A C14A C18A 119.90(18) C4A C3A C2A 120.24(17) C9A C14A C18A 121.39(17) C10A C15A C17A 111.05(16) C22A C27 A C29A 113.2(2) C10A C15A C16A 111.78(17) C32A C30A C26A 112.29(15) C17A C15A C16A 110.68(17) C32A C30A C31A 110.86(16) C14A C18A C19A 112.64(18) C26A C30A C31A 110.03(16) C14A C18A C20A 111.18(17) N3A C33A C34A 111.29(15) C19A C18A C20A 110.63(18) C3 9A C34A C35A 118.47(17) C26A C21A C22A 119.63(16) C39A C34A C33A 120.53(17) C26A C21A N2A 121.42(16) C35A C34A C33A 121.00(17) C22A C21A N2A 118.94(16) C36A C35A C34A 120.23(17) C23A C22A C21A 118.97(17) C35A C36A C37A 120.57(17) C23A C22A C27A 120.00 (18) C36A C37A C38A 120.38(17) C21A C22A C27A 121.02(17) C39A C38A C37A 118.21(16) C24A C23A C22A 121.56(18) C39A C38A C40A 119.63(16) C23A C24A C25A 119.37(18) C37A C38A C40A 122.04(16) C24A C25A C26A 121.20(18) C34A C39A C38A 122.02(17) C25A C26A C2 1A 119.10(17) N4A C40A C38A 113.48(15) C25A C26A C30A 118.98(16) C42A C41A C46A 120.24(16) C21A C26A C30A 121.83(16) C42A C41A N3A 120.06(16) C28A C27A C22A 111.7(2) C46A C41A N3A 119.69(16) C28A C27A C29A 110.1(2) C43A C42A C41A 118.43(17) C43A C42A C47A 119.45(17) C58A C53A N4A 120.59(16) C41A C42A C47A 122.11(16) C55A C54A C53A 118.75(17) C44A C43A C42A 121.43(18) C55A C54A C59A 120.31(17) C43A C44A C45A 119.75(18) C53A C54A C59A 120.84(16)

PAGE 241

241 Table A 9. Continued Bond Angle Bond Angle C46A C45A C44A 120.97(18) C56A C55A C54A 121.00(19) C45A C46A C41A 119.19(17) C57A C56A C55A 120.59(18) C45A C46A C50A 119.57(17) C56A C57A C58A 120.57(18) C41A C46A C50A 121.14(16) C57A C58A C53A 118.79(17) C48A C47A C42A 110.98(17) C57A C58A C62A 120.26(16) C48A C47A C49A 110.86(17) C53A C58A C62A 120.93(16) C42A C47A C49A 111.45(16) C54A C59A C61A 113.18(17) C46A C50A C51A 112.83(16) C54A C59A C60A 109.88(16) C46A C50A C52A 109.34(17) C61A C59A C60A 110.41(18) C51A C50A C52A 110.60(17) C58A C62A C64A 111 .06(16) C54A C53A C58A 120.29(16) C58A C62A C63A 112.31(17) C54A C53A N4A 119.13(15) C64A C62A C63A 110.34(17)

PAGE 242

242 Table A 10. Anisotropic displacement parameters (2x 103) for 4 The anisotropic displacement factor exponent takes the form: a* b* U12 ] _______________________________________________ ______________________ Atom U 11 U 22 U 33 U 23 U 13 U 12 Zn1A 17(1) 15(1) 20(1) 0(1) 2(1) 1(1) Zn2A 17(1) 16(1) 18(1) 1(1) 2(1) 0(1) N1A 19(1) 15(1) 23(1) 3(1) 3(1) 1(1) N2A 20(1) 16(1) 19(1) 0(1) 6(1) 1(1) N3A 21(1) 16(1) 21(1) 1(1) 7(1) 1(1) N4A 17(1) 14(1) 21(1) 0(1) 5(1) 1(1) C1A 24(1) 18(1) 29(1) 5(1) 7(1) 3(1) C2A 23(1) 18(1) 18(1) 4(1) 2 (1) 0(1) C3A 28(1) 20(1) 22(1) 3(1) 4(1) 0(1) C4A 22(1) 29(1) 31(1) 4(1) 7(1) 4(1) C5A 18(1) 28(1) 24(1) 2(1) 0(1) 3(1) C6A 23(1) 18(1) 16(1) 3(1) 3(1) 0(1) C7A 20(1) 18(1) 22(1) 3(1) 2(1) 3(1) C8A 25(1) 18(1) 21(1) 1(1) 6(1) 0(1) C9A 19(1) 13(1) 20(1) 2(1) 3(1) 1(1) C10A 24(1) 15(1) 21(1) 1(1) 2(1) 1(1) C11A 23(1) 22(1) 30(1) 0(1) 2(1) 1(1) C12A 20(1) 24(1) 41(1) 3(1) 6(1) 2(1) C13A 28(1) 24(1) 29(1) 6(1) 9(1) 1(1) C14A 25(1) 18(1) 23(1) 1(1) 3(1) 3(1) C 15A 23(1) 25(1) 22(1) 2(1) 2(1) 2(1) C16A 51(1) 32(1) 31(1) 10(1) 4(1) 10(1) C17A 30(1) 38(1) 25(1) 3(1) 0(1) 2(1) C18A 34(1) 30(1) 22(1) 5(1) 0(1) 3(1) C19A 70(2) 59(2) 28(1) 8(1) 4(1) 15(1) C20A 39(1) 37(1) 31(1) 8(1) 5(1) 5(1) C21A 20(1) 18(1) 18(1) 1(1) 4(1) 3(1) C22A 25(1) 26(1) 26(1) 4(1) 3(1) 0(1) C23A 34(1) 37(1) 25(1) 2(1) 9(1) 2(1) C24A 40(1) 30(1) 25(1) 12(1) 1(1) 3(1) C25A 29(1) 24(1) 25(1) 5(1) 2(1) 2(1) C26A 22(1) 20(1) 17(1) 1(1) 4(1) 0(1) C 27A 32(1) 30(1) 50(2) 2(1) 15(1) 5(1) C28A 63(2) 70(2) 44(2) 14(1) 9(1) 41(2) C29A 40(1) 74(2) 57(2) 34(2) 9(1) 17(1) C30A 19(1) 20(1) 22(1) 3(1) 2(1) 2(1) C31A 22(1) 28(1) 35(1) 4(1) 5(1) 0(1) C32A 30(1) 26(1) 25(1) 1(1) 2(1) 2(1) C33A 29(1) 17(1) 26(1) 2(1) 11(1) 2(1) C34A 25(1) 17(1) 18(1) 1(1) 6(1) 1(1) C35A 20(1) 26(1) 26(1) 1(1) 1(1) 5(1)

PAGE 243

243 Table A 10. Continued Atom U 11 U 22 U 33 U 23 U 13 U 12 C36A 22(1) 28(1) 25(1) 4(1) 4(1) 1(1) C37A 25(1) 19(1) 18(1) 2(1) 0(1) 2(1) C38A 21(1) 16(1) 20(1) 3(1) 5(1) 1(1) C39A 20(1) 16(1) 19(1) 2(1) 2(1) 3(1) C40A 21(1) 16(1) 36(1) 0(1) 7(1) 0(1) C41A 21(1) 16(1) 19(1) 1(1) 5(1) 2(1) C42A 22(1) 20(1) 24(1) 2(1) 3(1) 1(1) C43A 30(1) 22(1) 34(1) 4(1) 1(1) 6(1) C44A 40(1) 23(1) 33(1) 13(1) 2(1) 1(1) C45A 29(1) 29(1) 26(1) 5(1) 1(1) 4(1) C46A 22(1) 21(1) 23(1) 0(1) 3(1) 1(1) C47A 26(1) 23(1) 27(1) 4(1) 4(1) 5(1) C48A 27(1) 48(1) 45(2) 5(1) 4(1) 4(1) C49A 48(1) 34(1) 32(1 ) 4(1) 6(1) 3(1) C50A 26(1) 24(1) 29(1) 1(1) 4(1) 1(1) C51A 27(1) 38(1) 48(2) 15(1) 0(1) 1(1) C52A 31(1) 33(1) 43(1) 13(1) 5(1) 5(1) C53A 18(1) 13(1) 21(1) 1(1) 4(1) 0(1) C54A 22(1) 18(1) 20(1) 1(1) 2(1) 3(1) C55A 30(1) 26(1) 22(1) 4(1) 4(1) 7(1) C56A 24(1) 30(1) 34(1) 3(1) 6(1) 10(1) C57A 19(1) 28(1) 32(1) 1(1) 2(1) 4(1) C58A 20(1) 17(1) 23(1) 1(1) 1(1) 1(1) C59A 26(1) 35(1) 17(1) 2(1) 0(1) 10(1) C60A 34(1) 63(2) 30(1) 1(1) 6(1) 14(1) C61A 36(1) 43(1) 24(1 ) 4(1) 1(1) 11(1) C62A 22(1) 26(1) 23(1) 1(1) 2(1) 0(1) C63A 41(1) 39(1) 34(1) 6(1) 1(1) 16(1) C64A 41(1) 36(1) 25(1) 4(1) 2(1) 10(1)

PAGE 244

244 Figure A 136 Molecular structure of 6 with ellipsoids presented at 50% probability and hydrogen atoms rem oved for clarity. X ray experimental details for 6 : Data were collected at 100 K on a Bruker DUO system equipped with an APEX II area detector and a graphite monochromator utilizing MoK radiation ( = 0.71073 ). Cell parameters were refined using up to 9999 reflections. A hemisphere of data was collected using the scan method (0.5 frame width). Absorption corrections by integration were applied based on measured indexed crystal faces. The structure was solved by the Direct Methods in SHELXTL6, and r efined us ing full matrix least squares. The non H atoms were treated anisotropically, whereas the hydrogen atoms were calculated in ideal positions and were riding on their respective

PAGE 245

245 carbon atoms. A C 2 H 2 group of the coordinated THF ligand is disordered a nd refined in two parts with their site occupatio n factors dependently refined. A total of 366 parameters were refined in the final cycle of refinement using 5016 reflections with I > 2 (I) to yield R 1 and wR 2 of 4 .40% and 10.49%, respectively. Refinement was done using F 2

PAGE 246

246 Table A 11 Crystal data, structure solution and refinement for 6 identification code Mcg3 empirical formula C 37 H 52 Cr N 2 O formula weight 592.81 T (K) 100(2) 0.71073 crystal system Monoclinic space group C2/c a () 34.092(4) b () 11.7102(14) c () 17.247(2) (deg) 90 (deg) 104.138(2) (deg) 90 V ( 3 ) 6676.7(14) Z 8 calcd (Mg mm 3 ) 1.179 crystal size (mm 3 ) 0.38 x 0.19 x 0.03 abs coeff (mm 1 ) 0.373 F (000) 2560 range for data collection 1.84 to 27.50 limiting indices h k l no. of reflns collcd 52816 no. of ind reflns ( R int ) 7675 ( 0.0958 ) Completeness to = 27.50 100.0 % absorption corr Numerical refinement method Full matrix least squares on F 2 data / restraints / parameters 7675 / 0 / 366 R 1, a wR 2 b 0.0440 0.1049 [ 5016 ] R 1, a wR 2 b (all data) 0.0818 0.1166 GOF c on F 2 0.969 largest diff. peak and hole 0.542 and 0.610 e. 3 a R 1 = o | |F c o | b w R 2 = ( ( w ( F o 2 F c 2 ) 2 )/ ( w ( F o 2 ) 2 )) 1/2 c GOF = ( w ( F o 2 F c 2 ) 2 /( n p )) 1/2 where n is the number of data and p is the number of parameters refined.

PAGE 247

247 Table A 12. Atomic coordinates (x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 6 U (eq) is defined as one third of the trace of the orthogonalized Uij tensor. Atom x y z U(eq) Cr1 6396(1) 5490(1) 5681(1) 14(1) O1 5882(1) 5166(1) 4664(1) 19(1) N1 6314(1) 7096(2) 5714(1) 16(1) N2 6707(1) 4204(2) 5550(1) 16(1) C1 6003(1) 7794(2) 5227(1) 16(1) C2 5676(1) 8164(2) 5525(1) 17(1) C3 5378(1) 8841(2) 5035(1) 23(1) C4 5403(1) 9153(2) 4278(1) 26(1) C5 6030(1) 8100(2) 4446(1) 18(1) C6 5724(1) 8793(2) 3992(1) 23(1) C7 6600(1) 7775(2) 6334(1) 18(1) C8 6971(1) 7064(2) 6631(1) 15(1) C9 7352(1) 7415(2) 7078(1) 17(1) C10 7664(1) 6617(2) 7250(1) 18(1) C11 7611(1) 5498(2) 6976(1) 17(1) C12 7231(1) 5156(2) 6532(1) 15(1) C13 6915(1) 5932(2) 6384(1) 14(1) C14 7108(1) 4032(2) 6128(1) 16(1) C15 6647(1) 3370(2) 4922(1) 15(1) C16 6403(1) 2405(2) 4942(1) 18(1) C17 6343(1) 1626(2) 4311(1) 23(1) C18 6525(1) 1783(2) 3686(1) 24(1) C19 6775(1) 2710(2) 3684(1) 23(1) C20 6845(1) 3519(2) 4298(1) 17(1) C21 5638(1) 7883(2) 6366(1) 21(1) C22 5232(1) 7322(2) 6377(2) 31(1) C23 5697(1) 8948(2) 6899(1) 25(1) C24 6379(1) 7709(2) 41 09(1) 21(1) C25 6289(1) 7769(2) 3193(1) 29(1) C26 6773(1) 8367(2) 4462(2) 30(1) C27 6222(1) 2170(2) 5648(1) 22(1) C28 6368(1) 1019(2) 6034(1) 27(1) C29 5759(1) 2198(2) 5410(2) 37(1) C30 7126(1) 4519(2) 4279(1) 19(1) C31 7564(1) 4120(2) 4366(1) 26(1) C32 69 87(1) 5220(2) 3513(1) 26(1) C33 6134(1) 4948(2) 6572(1) 22(1) C34 5467(1) 5371(2) 4693(1) 22(1) C35 5258(1) 5793(2) 3874(2) 35(1) C36 5470(2) 5260(9) 3345(4) 24(1) C37 5862(2) 4716(7) 3871(4) 24(1)

PAGE 248

248 Table A 13 Bond lengths (in ) for 6 Bond Length Bond Length Cr1 N2 1.8870(18) C11 C12 1.394(3) Cr1 N1 1.9048(19) C12 C13 1.385(3) Cr1 C13 1.953(2) C12 C14 1.500(3) Cr1 C33 2.057(2) C15 C16 1.409(3) Cr1 O1 2.1878(15) C15 C20 1.413(3) O1 C34 1.448(3) C16 C17 1.396(3) O1 C37 1.453(7) C16 C2 7 1.517(3) N1 C1 1.436(3) C17 C18 1.383(3) N1 C7 1.488(3) C18 C19 1.380(3) N2 C15 1.436(3) C19 C20 1.397(3) N2 C14 1.496(3) C20 C30 1.518(3) C1 C2 1.408(3) C21 C23 1.533(3) C1 C5 1.418(3) C21 C22 1.535(3) C2 C3 1.397(3) C24 C25 1.535( 3) C2 C21 1.523(3) C24 C26 1.538(3) C3 C4 1.378(3) C27 C29 1.532(3) C4 C6 1.372(3) C27 C28 1.532(3) C5 C6 1.402(3) C30 C32 1.528(3) C5 C24 1.517(3) C30 C31 1.537(3) C7 C8 1.498(3) C34 C35 1.503(3) C8 C13 1.392(3) C35 C36 1.438(8) C8 C 9 1.400(3) C36 C37 1.555(10) C9 C10 1.394(3) C36 C37 1.555(10) C10 C11 1.390(3)

PAGE 249

249 Table A 14 Bond angles (in deg) for 6 Bond Angle Bond Angle N2 Cr1 N1 152.00(8) C10 C11 C12 119.0(2) N2 Cr1 C13 80.56(8) C13 C12 C11 119.4(2) N1 Cr1 C13 80.64(8) C13 C12 C14 111.93(18) N2 Cr1 C33 101.71(9) C11 C12 C14 128.6(2) N1 Cr1 C33 100.82(9) C12 C13 C8 121.7(2) C13 Cr1 C33 96.34(9) C12 C13 Cr1 119.12(16) N2 Cr1 O1 97.41(7) C8 C13 Cr1 118.63(16) N1 Cr1 O1 95.75(7) N2 C14 C12 107.30(17 ) C13 Cr1 O1 165.78(7) C16 C15 C20 120.9(2) C33 Cr1 O1 97.85(8) C16 C15 N2 120.16(19) C34 O1 C37 105.7(3) C20 C15 N2 118.96(19) C34 O1 Cr1 122.80(12) C17 C16 C15 118.7(2) C37 O1 Cr1 131.5(3) C17 C16 C27 119.7(2) C1 N1 C7 112.11(17) C15 C16 C27 121.58 (19) C1 N1 Cr1 129.60(14) C18 C17 C16 120.8(2) C7 N1 Cr1 118.28(13) C19 C18 C17 120.1(2) C15 N2 C14 110.46(17) C18 C19 C20 121.5(2) C15 N2 Cr1 130.78(14) C19 C20 C15 117.9(2) C14 N2 Cr1 118.43(13) C19 C20 C30 119.9(2) C2 C1 C5 120.76(19) C15 C20 C30 122.17(19) C2 C1 N1 119.90(19) C2 C21 C23 111.42(19) C5 C1 N1 119.34(19) C2 C21 C22 112.95(19) C3 C2 C1 118.5(2) C23 C21 C22 109.09(19) C3 C2 C21 118.8(2) C5 C24 C25 113.63(19) C1 C2 C21 122.73(19) C5 C24 C26 112.70(19) C4 C3 C2 121.3(2) C25 C24 C26 108.8(2) C6 C4 C3 119.9(2) C16 C27 C29 112.0(2) C6 C5 C1 117.7(2) C16 C27 C28 110.86(19) C6 C5 C24 120.5(2) C29 C27 C28 109.8(2) C1 C5 C24 121.83(19) C20 C30 C32 111.73(18) C4 C6 C5 121.8(2) C20 C30 C31 111.43(19) N1 C7 C8 107.39(17) C32 C30 C31 109. 63(19) C13 C8 C9 119.3(2) O1 C34 C35 105.44(19) C13 C8 C7 112.51(19) C36 C35 C34 104.8(3) C9 C8 C7 128.2(2) C35 C36 C37 107.6(5) C10 C9 C8 118.6(2) O1 C37 C36 103.7(5) C11 C10 C9 122.0(2)

PAGE 250

250 Figure A 137 Molecular structure of 16 Ph with ellip soids presented at 50% probability and hydrogen atoms removed for clarity. X Ray experimental for 16 Ph : X Ray Intensity data were collected at 100 K on a Bruker SMART diffractometer using MoK radiation ( = 0.71073 ) and an APEXII CCD area detector. R aw data frames were read by program SAINT 1 and integrated using 3D profiling algorithms. The resulting data were reduced to produce hkl reflections and their intensities and estimated standard deviations. The data were corrected for Lorentz and polarizatio n

PAGE 251

251 effects and numerical absorption corrections were applied based on indexed and measured faces. The structure was solved and refined in SHELXTL6.1, using full m atrix least squares refinement. The non H atoms were refined with anisotropic thermal parameter s and all of the H atoms were calculated in idealized positions and refine d riding on their parent atoms. The asymmetric unit consists of the W complex and a half ether solvent molecule. The solvent is located on an inversion center and was also further di sor dered and refined in two parts. In the final cycle of refinement, 8897 reflections (of which 8071 are observed with I > 2 (I)) were used to refine 456 parameters and the resulting R 1 wR 2 and S (goodness of fit) were 2.62 %, 6.39 % and 1.050 respectively. The refinement was carried out by minimizing the wR 2 function using F 2 rather than F values. R 1 is calculated to provide a reference to the conventional R value but its function is not minimized.

PAGE 252

252 Table A 15. Crystal data and structure refinement for 16 Ph Identification code mcg7 Empirical formula C45 H56 O3.50 W Formula weight 836.75 Temperature 100(2) K Wav elength 0.71073 Crystal system Triclinic Space group a = 9.4199(4) b = 12.1830(5) c = 17.6797(7) Volume 1939.34(14) 3 Z 2 Density (calculated) 1.433 Mg/m 3 Absorption coefficient 3.018 mm 1 F(000) 856 Crystal size 0.19 x 0.12 x 0.04 mm 3 Theta range for data collection 1.72 to 27.50. Index ranges Reflections collected 53616 Independent reflections 8897 [R(int) = 0.0476] Completeness to theta = 27.50 100.0 % Absorption correction Integration Max. and min. tra nsmission 0.8863 and 0.5978 Refinement method Full matrix least squares on F 2 Data / restraints / parameters 8897 / 0 / 456 Goodness of fit on F 2 1.050 Final R indices [I>2sigma(I)] R1 = 0.0262, wR2 = 0.0639 [8071] R indices (all data) R1 = 0.0302, wR2 = 0 .0655 Largest diff. peak and hole 2.205 and 2.364 e. 3 o | |F c o | o 2 F c 2 ) 2 o 2 ) 2 ]] 1/2 o 2 F c 2 ) 2 ] / (n p)] 1/2 2 (F o 2 )+(m*p) 2 +n*p], p = [max(F o 2 ,0)+ 2* F c 2 ]/3, m & n are constants.

PAGE 253

253 Table A 16. Atomic coordinates (x 10 4 ) and equivalent isotropic displac ement parameters ( 2 x 10 3 ) for 16 Ph U (eq) is defined as one third of the trace of the orthogonalized U ij tensor. Atom x y z U(eq) W1 6059(1) 8051(1) 7409(1) 15(1) O1 6525(2) 9572(2) 7066(1) 21(1) O2 4609(2) 6641(2) 7466(1) 17(1) O3 3923(2) 8722(2) 7393 (1) 22(1) C1 7315(3) 9960(3) 6529(2) 21(1) C2 8360(4) 11008(3) 6695(2) 26(1) C3 9143(4) 11359(3) 6120(2) 30(1) C4 8884(4) 10746(3) 5400(2) 33(1) C5 7810(4) 9752(3) 5235(2) 29(1) C6 7013(4) 9340(3) 5795(2) 23(1) C7 5787(4) 8318(3) 5580(2) 22(1) C8 4718(4) 8 274(3) 4917(2) 29(1) C9 3547(4) 7317(3) 4699(2) 28(1) C10 3416(4) 6431(3) 5152(2) 26(1) C11 4469(3) 6456(3) 5822(2) 19(1) C12 5699(3) 7386(3) 6026(2) 18(1) C13 4302(3) 5475(3) 6281(2) 19(1) C14 3935(3) 4390(3) 5880(2) 24(1) C15 3688(4) 3446(3) 6268(2) 30(1 ) C16 3825(4) 3570(3) 7061(2) 27(1) C17 4186(3) 4628(3) 7497(2) 22(1) C18 4387(3) 5589(2) 7086(2) 17(1) C19 8640(4) 11736(3) 7472(2) 28(1) C20 9669(4) 12891(3) 7469(2) 38(1) C21 7173(4) 11964(3) 7651(2) 36(1) C22 9383(4) 11135(3) 8115(2) 33(1) C23 4388(4) 4709(3) 8382(2) 24(1) C24 5990(4) 5329(3) 8739(2) 30(1) C25 3286(4) 5325(3) 8662(2) 31(1) C26 4143(4) 3547(3) 8691(2) 34(1) C27 6950(3) 8436(2) 8563(2) 20(1) C28 6896(4) 8891(3) 9373(2) 36(1) C29 6736(10) 10060(4) 9380(4) 132(4) C30 8258(11) 8815(14) 9889( 4) 336(12) C31 5641(11) 8214(5) 9644(4) 140(4) C32 7868(3) 8035(2) 8206(2) 20(1) C33 6955(3) 7345(2) 6689(2) 16(1) C34 8146(3) 6810(2) 6538(2) 16(1) C35 8658(3) 6899(2) 5840(2) 20(1) C36 9786(4) 6390(3) 5702(2) 26(1) C37 10421(4) 5782(3) 6245(2) 29(1)

PAGE 254

254 Tabl e A 16. Continued Atom x y z U(eq) C38 9927(4) 5683(3) 6939(2) 28(1) C39 8800(3) 6185(3) 7085(2) 22(1) C40 2722(5) 8210(3) 7742(3) 57(1) C41 1744(5) 9063(4) 7677(4) 69(2) C42 1990(6) 9606(6) 6935(3) 79(2) C43 3321(5) 9306(5) 6763(3) 63(2)

PAGE 255

255 Table A 17. Bo nd lengths () for 16 Ph Bond Length Bond Length W1 C33 1.905(2) C13 C18 1.409(3) W1 O1 1.9702(16) C14 C15 1.376(4) W1 O2 1.9751(16) C15 C16 1.380(4) W1 C32 2.009(2) C16 C17 1.401(4) W1 C27 2.044(3) C17 C18 1.413(3) W1 O3 2.3245(16) C17 C23 1.537(4) W1 C12 2.468(2) C19 C22 1.532(4) O1 C1 1.358(3) C19 C20 1.532(4) O2 C18 1.367(3) C19 C21 1.549(3) O3 C40 1.433(3) C23 C26 1.536(3) O3 C43 1.448(4) C23 C24 1.536(4) C1 C6 1.411(4) C23 C25 1.537(3) C1 C2 1.413(4) C27 C32 1 .310(3) C2 C3 1.398(4) C27 C28 1.515(4) C2 C19 1.536(4) C28 C31 1.379(6) C3 C4 1.386(4) C28 C29 1.602(6) C4 C5 1.379(4) C28 C30 1.685(7) C5 C6 1.402(3) C33 C34 1.467(3) C6 C7 1.482(4) C34 C35 1.404(3) C7 C8 1.391(4) C34 C39 1.405(3) C 7 C12 1.419(3) C35 C36 1.388(3) C8 C9 1.388(4) C36 C37 1.381(4) C9 C10 1.380(4) C37 C38 1.394(4) C10 C11 1.394(3) C38 C39 1.386(3) C11 C12 1.413(4) C40 C41 1.524(4) C11 C13 1.484(3) C41 C42 1.545(6) C12 C33 1.519(3) C42 C43 1.454(5) C1 3 C14 1.403(3)

PAGE 256

256 Table A 18. Bond angles (in deg) for 16 Ph Bond Angle Bond Angle C33 W1 O1 96.05(8) C7 C12 W1 110.02(16) C33 W1 O2 93.09(8) C33 C12 W1 50.50(11) O1 W1 O2 150.27(7) C14 C13 C18 119.2(2) C33 W1 C32 86.66(10) C14 C13 C11 117.8(2) O 1 W1 C32 103.19(9) C18 C13 C11 122.9(2) O2 W1 C32 105.54(8) C15 C14 C13 120.6(2) C33 W1 C27 124.25(10) C14 C15 C16 119.5(2) O1 W1 C27 99.54(9) C15 C16 C17 122.8(3) O2 W1 C27 98.48(8) C16 C17 C18 117.0(2) C32 W1 C27 37.70(9) C16 C17 C23 120.3(2) C33 W 1 O3 137.62(8) C18 C17 C23 122.8(2) O1 W1 O3 75.07(6) O2 C18 C13 119.1(2) O2 W1 O3 79.13(6) O2 C18 C17 120.0(2) C32 W1 O3 135.66(8) C13 C18 C17 120.8(2) C27 W1 O3 98.13(8) C22 C19 C20 107.7(2) C33 W1 C12 37.99(8) C22 C19 C2 109.3(2) O1 W1 C12 84.62(8 ) C20 C19 C2 111.8(2) O2 W1 C12 85.38(8) C22 C19 C21 110.5(2) C32 W1 C12 124.55(9) C20 C19 C21 106.7(2) C27 W1 C12 162.23(8) C2 C19 C21 110.8(2) O3 W1 C12 99.64(7) C26 C23 C24 106.8(2) C1 O1 W1 130.34(14) C26 C23 C25 106.9(2) C18 O2 W1 130.42(14) C24 C23 C25 110.4(2) C40 O3 C43 107.6(3) C26 C23 C17 112.8(2) C40 O3 W1 124.03(16) C24 C23 C17 108.9(2) C43 O3 W1 122.44(17) C25 C23 C17 110.9(2) O1 C1 C6 119.0(2) C32 C27 C28 138.5(2) O1 C1 C2 119.8(2) C32 C27 W1 69.70(15) C6 C1 C2 121.1(2) C28 C27 W1 151.77(19) C3 C2 C1 117.0(3) C31 C28 C27 116.5(4) C3 C2 C19 120.8(2) C31 C28 C29 113.6(4) C1 C2 C19 122.2(2) C27 C28 C29 108.5(3) C4 C3 C2 122.7(3) C31 C28 C30 110.7(4)

PAGE 257

257 Table A 18. Continued Bond Angle Bond Angle C5 C4 C3 119.5(3) C27 C28 C30 107.0 (3) C4 C5 C6 120.7(3) C29 C28 C30 99.1(4) C5 C6 C1 119.0(3) C27 C32 W1 72.60(15) C5 C6 C7 119.3(2) C34 C33 C12 119.1(2) C1 C6 C7 121.5(2) C34 C33 W1 149.28(18) C8 C7 C12 119.2(3) C12 C33 W1 91.51(13) C8 C7 C6 119.1(2) C35 C34 C39 118.0(2) C12 C7 C6 121.7(2) C35 C34 C33 121.3(2) C9 C8 C7 120.8(2) C39 C34 C33 120.7(2) C10 C9 C8 120.1(2) C36 C35 C34 120.9(2) C9 C10 C11 121.0(3) C37 C36 C35 120.4(2) C10 C11 C12 119.1(2) C36 C37 C38 119.6(2) C10 C11 C13 119.1(2) C39 C38 C37 120.4(2) C12 C11 C13 121. 7(2) C38 C39 C34 120.7(2) C11 C12 C7 119.6(2) O3 C40 C41 102.8(3) C11 C12 C33 119.5(2) C40 C41 C42 104.1(3) C7 C12 C33 120.8(2) C43 C42 C41 104.8(3) C11 C12 W1 109.89(15) O3 C43 C42 108.4(3)

PAGE 258

258 Table A 19. Anisotropic displacement parameters ( 2 x 10 3 ) for 16 Ph The anisotropic displacement factor exponent takes the form: 2 2 [ h 2 a* 2 U 11 + ... + 2 h k a* b* U 12 ] Atom U 11 U 22 U 33 U 23 U 13 U 12 W1 15(1) 17(1) 14(1) 2(1) 3(1) 5(1) O1 24(1) 20(1) 21(1) 6(1) 10(1) 8(1) O2 18(1) 18(1) 16(1) 1(1) 5 (1) 5(1) O3 18(1) 23(1) 27(1) 2(1) 5(1) 7(1) C1 23(1) 22(1) 27(1) 11(1) 12(1) 13(1) C2 26(1) 22(1) 33(2) 12(1) 11(1) 13(1) C3 27(1) 23(1) 48(2) 16(1) 17(1) 11(1) C4 39(2) 28(2) 44(2) 18(1) 27(2) 17(1) C5 41(2) 28(1) 31(2) 14(1) 21(1) 21( 1) C6 28(1) 24(1) 26(1) 12(1) 13(1) 17(1) C7 28(1) 27(1) 17(1) 4(1) 10(1) 17(1) C8 36(2) 38(2) 17(1) 8(1) 9(1) 24(1) C9 29(2) 52(2) 14(1) 2(1) 3(1) 25(1) C10 17(1) 40(2) 18(1) 2(1) 4(1) 10(1) C11 16(1) 27(1) 14(1) 1(1) 5(1) 9(1) C12 18( 1) 26(1) 14(1) 1(1) 5(1) 10(1) C13 12(1) 25(1) 20(1) 2(1) 4(1) 4(1) C14 19(1) 30(1) 22(1) 6(1) 7(1) 4(1) C15 28(2) 23(1) 36(2) 10(1) 13(1) 0(1) C16 28(1) 20(1) 35(2) 1(1) 14(1) 4(1) C17 19(1) 22(1) 23(1) 0(1) 8(1) 4(1) C18 13(1) 20(1) 20(1) 2(1) 5(1) 3(1) C19 26(1) 19(1) 38(2) 7(1) 10(1) 5(1) C20 42(2) 27(2) 43(2) 9(1) 6(2) 1(1) C21 35(2) 25(1) 49(2) 2(1) 14(2) 12(1) C22 38(2) 28(1) 34(2) 9(1) 9(1) 9(1) C23 32(2) 21(1) 22(1) 7(1) 10(1) 6(1) C24 35(2) 29(1) 24(2) 8 (1) 1(1) 4(1) C25 43(2) 32(2) 24(2) 6(1) 17(1) 11(1) C26 43(2) 26(1) 35(2) 12(1) 14(1) 5(1) C27 22(1) 18(1) 20(1) 0(1) 1(1) 3(1) C28 34(2) 52(2) 21(1) 13(1) 3(1) 21(2) C32 18(1) 16(1) 23(1) 4(1) 4(1) 1(1) C33 16(1) 17(1) 16(1) 4(1) 2(1 ) 3(1) C34 13(1) 13(1) 20(1) 1(1) 2(1) 1(1) C35 18(1) 19(1) 23(1) 2(1) 3(1) 4(1) C36 21(1) 27(1) 30(2) 0(1) 9(1) 5(1) C37 18(1) 25(1) 44(2) 0(1) 5(1) 11(1) C38 22(1) 23(1) 37(2) 7(1) 1(1) 10(1) C39 22(1) 20(1) 26(1) 6(1) 4(1) 4(1)

PAGE 259

259 Table A 19. Continued Atom U 11 U 22 U 33 U 23 U 13 U 12 C40 35(2) 32(2) 118(4) 16(2) 45(2) 11(2) C41 48(2) 48(2) 131(4) 21(2) 48(3) 24(2) C42 71(3) 127(4) 70(3) 25(3) 19(2) 69(3) C43 60(2) 117(4) 40(2) 32(2) 17(2) 64(3)

PAGE 260

260 Figure A 138 Molecular stru cture of 17 Ph with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. X Ray experimental for 17 Ph : X Ray Intensity data were collected at 100 K on a Bruker SMART diffractometer using MoK radiation ( = 0.71073 ) and an APEXII CCD area detector. Raw data frames were read by program SAINT 1 and integrated using 3D profiling algorithms. The resulting data were reduced to produce hkl reflections and their intensities and estimated standard d eviations. The data were corrected for Lorentz and polarization

PAGE 261

261 effects and numerical absorption corrections were applied based on indexed and measured faces. The structure was solved and refined in SHELXTL6.1, using full matrix least squares refinemen t. T he non H atoms were refined with anisotropic thermal parameters and all of the H atoms were calculated in idealized positions and refine d riding on their parent atoms. In the final cycle of refinement, 19344 reflections (of which 14608 are observed with I > 2 (I)) were used to refine 948 parameters and the resulting R 1 wR 2 and S (goodness of fit) were 3.77 %, 7.48 % and 1.023 respectively. The refinement was carried out by minimizing the wR 2 function using F 2 rather than F values. R 1 is calculated to provid e a reference to the conventional R value but its function is not minimized. The toluene molecule were disordered and could not be modeled properly, thus program SQUEEZE, a part of the PLATON package of crystallographic software, was used to calculate the solvent disorder area and remove its contribution to the overall intensity data.

PAGE 262

262 Table A 20. Crystal data and structure refinement for 17 Ph Identification code mcg8 Empirical formula C48 H62 O4 W Formula weight 886.83 Temperatur e 100(2) K Wavelength 0.71073 Crystal system Triclinic Space group P 1 a = 12.5307(3) b = 18.2485(4) c = 19.5913(4) Volume 4210.28(16) 3 Z 4 Density (calculated) 1.399 Mg/m 3 Absorption coeffici ent 2.786 mm 1 F(000) 1824 Crystal size 0.17 x 0.13 x 0.05 mm 3 Theta range for data collection 1.73 to 27.50. Index ranges Reflections collected 65439 Independent reflections 19344 [R(int) = 0.0665] Completeness to theta = 27. 50 99.9 % Absorption correction Numerical Max. and min. transmission 0.8710 and 0.6503 Refinement method Full matrix least squares on F 2 Data / restraints / parameters 19344 / 0 / 948 Goodness of fit on F 2 1.023 Final R indices [I>2sigma(I)] R1 = 0.0377, wR2 = 0.0748 [14608] R indices (all data) R1 = 0.0576, wR2 = 0.0828 Largest diff. peak and hole 1.024 and 0.926 e. 3 o | |F c o | o 2 F c 2 ) 2 o 2 ) 2 ]] 1/2 o 2 F c 2 ) 2 ] / (n p)] 1/2 2 (F o 2 )+(m*p) 2 +n*p], p = [max(F o 2 ,0)+ 2* F c 2 ]/3, m & n are constants.

PAGE 263

263 Table A 21. Atomic coordinates ( x 10 4 ) and equivalent isotropic displacement parameters ( 2 x 10 3 ) for 17 Ph U (eq) is defined as one third of the trace of the orthogonalized U ij tensor. Atom x y z U(eq) W1 6153(1) 6147(1) 2817(1) 14(1) W2 3908(1) 10647(1) 2236(1) 16(1) O1 4793(2) 5979(2) 2192(1) 17(1) O2 6984(2) 5834( 2) 3590(1) 16(1) O3 5266(2) 4827(2) 2800(1) 20(1) C1 3991(3) 6321(2) 2157(2) 19(1) C2 3554(4) 6479(2) 1508(2) 22(1) C3 2689(4) 6797(3) 1504(2) 26(1) C4 2248(4) 6965(3) 2106(2) 27(1) C5 2684(4) 6808(3) 2727(2) 25(1) C6 3547(3) 6479(2) 2763(2) 19(1) C7 3891( 3) 6231(2) 3438(2) 19(1) C8 3023(4) 5774(2) 3821(2) 21(1) C9 3267(4) 5513(2) 4453(2) 22(1) C10 4376(3) 5694(2) 4703(2) 19(1) C11 5271(3) 6135(2) 4338(2) 19(1) C12 5032(3) 6437(2) 3700(2) 16(1) C13 6451(3) 6296(2) 4621(2) 18(1) C14 6736(4) 6565(3) 5307(2) 2 5(1) C15 7799(4) 6672(3) 5602(2) 27(1) C16 8602(4) 6508(3) 5225(2) 26(1) C17 8377(3) 6235(2) 4547(2) 19(1) C18 7264(3) 6131(2) 4241(2) 17(1) C19 4054(4) 6336(3) 844(2) 23(1) C20 3409(4) 6511(3) 204(2) 34(1) C21 3995(4) 5485(3) 753(2) 31(1) C22 5297(4) 6886 (3) 851(2) 32(1) C23 9311(4) 6107(3) 4142(2) 23(1) C24 9618(4) 6709(3) 3591(2) 33(1) C25 8933(4) 5282(3) 3816(3) 32(1) C26 10393(4) 6213(3) 4605(2) 34(1) C27 7274(3) 6197(2) 2103(2) 18(1) C28 7774(4) 5787(3) 1597(2) 26(1) C29 7500(6) 5987(4) 868(3) 38(2) C 30 7311(6) 4913(4) 1655(4) 38(2) C31 9074(5) 6064(4) 1734(3) 37(2) C32 7358(3) 6913(2) 2295(2) 19(1) C33 6011(3) 6993(2) 3348(2) 16(1) C34 6457(4) 7805(2) 3604(2) 19(1) C35 7627(4) 8217(3) 3654(2) 30(1) C36 8043(4) 8993(3) 3875(3) 40(1)

PAGE 264

264 Table A 21. Continu ed Atom x y z U(eq) C37 7312(5) 9367(3) 4063(3) 42(1) C38 6161(5) 8971(3) 4045(2) 34(1) C39 5733(4) 8190(2) 3821(2) 24(1) C40 7964(4) 7720(3) 2098(2) 29(1) C41 4091(4) 4431(3) 2551(3) 39(1) C42 3792(4) 3599(2) 2758(2) 24(1) C43 4946(4) 3497(3) 2879(3) 30( 1) C44 5686(4) 4278(3) 3160(3) 35(1)

PAGE 265

265 Table A 22 Bond lengths (in ) for 17 Ph Bond Length Bond Length W1 C33 1.910(4) C13 C18 1.405(5) W1 O1 1.967(3) C14 C15 1.369(6) W1 O2 1.984(3) C15 C16 1.391(6) W1 C27 2.026(4) C16 C17 1.386(6) W1 C32 2.030(4) C17 C18 1.434(6) W1 O3 2.288(3) C17 C23 1.533(6) W1 C12 2.452(4) C19 C21 1.536(6) O1 C1 1.348(5) C19 C22 1.544(6) O2 C18 1.354(5) C19 C20 1.544(6) O3 C44 1.453(5) C23 C24 1.527(6) O3 C41 1.454(5) C23 C25 1.531(6) C1 C6 1.408 (6) C23 C26 1.537(6) C1 C2 1.425(6) C27 C32 1.321(6) C2 C3 1.389(6) C27 C28 1.516(6) C2 C19 1.534(6) C28 C30 1.511(8) C3 C4 1.404(6) C28 C29 1.528(8) C4 C5 1.378(6) C28 C31 1.540(8) C5 C6 1.401(6) C32 C40 1.484(6) C6 C7 1.489(6) C33 C3 4 1.463(6) C7 C8 1.401(6) C34 C39 1.400(6) C7 C12 1.412(6) C34 C35 1.401(6) C8 C9 1.387(6) C35 C36 1.387(6) C9 C10 1.373(6) C36 C37 1.375(7) C10 C11 1.390(5) C37 C38 1.378(7) C11 C12 1.430(6) C38 C39 1.396(6) C11 C13 1.478(6) C41 C42 1.507(6) C12 C33 1.520(5) C42 C43 1.524(6) C13 C14 1.403(6) C43 C44 1.491(6)

PAGE 266

266 Table A 23. Bond angles (in deg) for 17 Ph Bond Angle Bond Angle C33 W1 O1 96.78(14) C33 C12 W1 51.16(19) C33 W1 O2 92.21(14) C14 C13 C18 119.5(4) O1 W1 O2 151.66(11 ) C14 C13 C11 118.5(4) C33 W1 C27 127.42(17) C18 C13 C11 121.8(4) O1 W1 C27 98.10(14) C15 C14 C13 120.4(4) O2 W1 C27 97.57(14) C14 C15 C16 120.0(4) C33 W1 C32 89.64(17) C17 C16 C15 122.7(4) O1 W1 C32 101.06(14) C16 C17 C18 116.9(4) O2 W1 C32 105.84(1 4) C16 C17 C23 120.6(4) C27 W1 C32 38.01(16) C18 C17 C23 122.4(4) C33 W1 O3 133.51(14) O2 C18 C13 120.1(4) O1 W1 O3 76.6(1) O2 C18 C17 119.2(3) O2 W1 O3 77.73(10) C13 C18 C17 120.6(4) C27 W1 O3 99.01(14) C2 C19 C21 111.7(4) C32 W1 O3 136.84(14) C2 C1 9 C22 109.0(4) C33 W1 C12 38.32(14) C21 C19 C22 110.3(4) O1 W1 C12 85.62(12) C2 C19 C20 112.0(4) O2 W1 C12 84.96(12) C21 C19 C20 106.5(4) C27 W1 C12 165.73(15) C22 C19 C20 107.2(4) C32 W1 C12 127.79(15) C24 C23 C25 110.4(4) O3 W1 C12 95.25(12) C24 C2 3 C17 108.9(4) C1 O1 W1 132.4(3) C25 C23 C17 111.4(4) C18 O2 W1 130.6(2) C24 C23 C26 107.7(4) C44 O3 C41 108.7(3) C25 C23 C26 107.1(4) C44 O3 W1 125.6(2) C17 C23 C26 111.3(4) C41 O3 W1 124.4(2) C32 C27 C28 139.0(4) O1 C1 C6 119.3(4) C32 C27 W1 71.2(2 ) O1 C1 C2 120.1(4) C28 C27 W1 149.8(3) C6 C1 C2 120.5(4) C30 C28 C27 111.5(4) C3 C2 C1 117.4(4) C30 C28 C29 108.9(5) C3 C2 C19 121.4(4) C27 C28 C29 109.8(4) C1 C2 C19 121.2(4) C30 C28 C31 108.8(5) C2 C3 C4 122.6(4) C27 C28 C31 109.5(4)

PAGE 267

267 Table A 23. Continued Bond Angle Bond Angle C5 C4 C3 119.1(4) C29 C28 C31 108.2(5) C4 C5 C6 120.9(4) C27 C32 C40 138.2(4) C5 C6 C1 119.5(4) C27 C32 W1 70.8(2) C5 C6 C7 118.8(4) C40 C32 W1 150.6(3) C1 C6 C7 121.4(4) C34 C33 C12 117.9(3) C8 C7 C12 119.6(4) C34 C 33 W1 150.6(3) C8 C7 C6 117.2(4) C12 C33 W1 90.5(2) C12 C7 C6 123.2(4) C39 C34 C35 117.8(4) C9 C8 C7 121.1(4) C39 C34 C33 121.1(4) C10 C9 C8 119.6(4) C35 C34 C33 121.0(4) C9 C10 C11 121.7(4) C36 C35 C34 120.8(4) C10 C11 C12 119.4(4) C37 C36 C35 120.3 (5) C10 C11 C13 119.6(4) C36 C37 C38 120.4(5) C12 C11 C13 121.0(4) C37 C38 C39 119.7(5) C7 C12 C11 118.5(4) C38 C39 C34 120.8(4) C7 C12 C33 122.7(3) O3 C41 C42 106.8(4) C11 C12 C33 118.7(4) C41 C42 C43 103.2(4) C7 C12 W1 108.9(3) C44 C43 C42 102.9(4) C11 C12 W1 110.4(3) O3 C44 C43 105.0(4)

PAGE 268

268 Table A 24. Anisotropic displacement parameters ( x 10 3 ) for 17 Ph The anisotropic displacement factor exponent takes the form: 2 [h 2 a*U 11 U 12 ]. Atom U 11 U 22 U 33 U 23 U 13 U 12 W1 15(1) 13 (1) 15(1) 0(1) 2(1) 5(1) O1 19(2) 15(2) 19(2) 0(1) 1(1) 8(1) O2 20(2) 15(2) 14(1) 2(1) 2(1) 5(1) O3 18(2) 15(2) 24(2) 2(1) 4(1) 5(1) C1 21(2) 13(2) 23(2) 1(2) 2(2) 5(2) C2 26(2) 18(2) 22(2) 4(2) 1(2) 9(2) C3 26(2) 24(2) 27(3) 5(2) 4(2) 9(2) C4 20(2) 25(2) 38(3) 7(2) 0(2) 12(2) C5 27(2) 24(2) 26(2) 1(2) 2(2) 11(2) C6 17(2) 16(2) 24(2) 2(2) 1(2) 5(2) C7 22(2) 13(2) 24(2) 0(2) 6(2) 9(2) C8 18(2) 20(2) 25(2) 0(2) 2(2) 7(2) C9 20(2) 22(2) 25(2) 9(2) 9(2) 6(2) C10 21( 2) 21(2) 18(2) 5(2) 3(2) 11(2) C11 21(2) 19(2) 17(2) 2(2) 3(2) 6(2) C12 22(2) 13(2) 14(2) 2(2) 0(2) 7(2) C13 20(2) 18(2) 17(2) 2(2) 0(2) 6(2) C14 30(3) 29(3) 18(2) 2(2) 7(2) 12(2) C15 30(3) 34(3) 13(2) 6(2) 1(2) 4(2) C16 21(2) 28(3) 26(2) 3(2) 3(2) 6(2) C17 18(2) 19(2) 19(2) 3(2) 2(2) 4(2) C18 21(2) 16(2) 14(2) 1(2) 2(2) 5(2) C19 27(2) 23(2) 18(2) 0(2) 5(2) 9(2) C20 38(3) 40(3) 26(3) 2(2) 7(2) 16(2) C21 45(3) 23(3) 24(3) 3(2) 2(2) 13(2) C22 33(3) 41(3) 21(2) 5 (2) 5(2) 10(2) C23 17(2) 29(3) 23(2) 5(2) 3(2) 8(2) C24 22(2) 43(3) 31(3) 1(2) 9(2) 6(2) C25 25(3) 29(3) 44(3) 13(2) 3(2) 14(2) C26 19(2) 48(3) 34(3) 10(2) 5(2) 14(2) C27 18(2) 21(2) 16(2) 1(2) 1(2) 8(2) C28 27(2) 31(3) 21(2) 3(2) 6(2) 10(2) C32 16(2) 23(2) 15(2) 1(2) 0(2) 3(2) C33 18(2) 16(2) 14(2) 3(2) 0(2) 6(2) C34 27(2) 15(2) 15(2) 2(2) 7(2) 6(2) C35 29(3) 25(3) 37(3) 1(2) 5(2) 9(2) C36 34(3) 23(3) 48(3) 8(2) 4(3) 9(2) C37 61(4) 15(2) 43(3) 9(2) 9(3) 1(3) C 38 56(3) 19(2) 29(3) 0(2) 12(2) 14(2) C39 34(3) 16(2) 23(2) 2(2) 11(2) 8(2) C40 32(3) 22(2) 30(3) 1(2) 8(2) 5(2)

PAGE 269

269 Table A 24. Continued Atom U 11 U 22 U 33 U 23 U 13 U 12 C41 27(3) 17(3) 69(4) 3(2) 13(3) 5(2) C42 22(2) 19(2) 25(2) 2(2) 4(2) 0 (2) C43 28(3) 19(2) 45(3) 1(2) 1(2) 9(2) C44 31(3) 24(3) 47(3) 2(2) 12(2) 7(2)

PAGE 270

270 Figure A 139 Molecular structure of 18A with ellipsoids presented at 50% probability and hydrogen atoms removed for clarity. X Ray experimental for 18A : X Ray Int ensity data were collected at 100 K on a Bruker DUO diffractometer using MoK radiation ( = 0.71073 ) an d an APEXII CCD area detector. Raw data frames were read by program SAINT and integrated using 3D profiling algorithms. The resulting data were reduce d to produce hkl reflections and their intensities and estimated standard deviations. The data were corrected for Lorentz and polarization

PAGE 271

271 effects and numerical absorption corrections were applied based on indexed and measured faces. The structure was sol ved and refined in SHELXTL6.1, using full matrix least squares refinement. The non H atoms were refined with anisotropic thermal parameters and all of the H atoms were calculated in idealized positions and refined riding on their parent atoms. The asymmetr ic unit consists of two W complexes and an eth er solvent molecule. In the final cycle of refinement, 73336 reflections (of which 12987 are observed with I > 2 (I)) were used to refine 986 parameters and the resulting R 1 wR 2 and S (goodness of fit) were 3. 61 %, 6.94 % and 0.956 respectively. The refinement was carried out by minimizing the wR 2 function using F 2 rather than F values. R 1 is calculated to provide a reference to the conventional R value but its function is not minimized.

PAGE 272

272 Table A 25. Crystal data and structure refinement for 18A Identification code mcg9 Empirical formula C48 H50 O2 W Formula weight 879.79 Temperature 100(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2 1 /c a = 9.6683(5) = 90 b = 40.736(2) = 97.047(1) c = 21.0306(13) = 90 Volume 8220.3(8) 3 Z 8 Density (calculated) 1.422 Mg/m 3 Absorption coefficient 2.851 mm 1 F(000) 3592 Crystal size 0.12 x 0.09 x 0.05 mm 3 Theta range for data collection 1.00 to 27.50. Index ranges Reflections collected 73336 Independent reflections 18795 [R(int) = 0.0534] Completeness to theta = 27.50 99.4 % Absorption correction Integration Max. and min. transmission 0.8801 and 0.7188 Refinement method Full mat rix least squares on F 2 Data / restraints / parameters 18795 / 0 / 986 Goodness of fit on F 2 0.956 Final R indices [I>2sigma(I)] R1 = 0.0361, wR2 = 0.0577 [12987] R indices (all data) R1 = 0.0700, wR2 = 0.0694 Largest diff. peak and hole 1.435 and 1.767 e 3 o | |F c o | o 2 F c 2 ) 2 o 2 ) 2 ]] 1/2 o 2 F c 2 ) 2 ] / (n p)] 1/2 2 (F o 2 )+(m*p) 2 +n*p], p = [max(F o 2 ,0)+ 2* F c 2 ]/3, m & n are constants.

PAGE 273

273 Table A 26. Atomic coordinates ( x 10 4 ) and equivalent isotropic d isplacement parameters ( 2 x 10 3 )for 18A U (eq) is defined as one third of the trace of the orthogonalized U ij tensor. Atom x y z U(eq) W1 3346(1) 9948(1) 2170(1) 11(1) O1 4512(3) 10228(1) 2795(1) 13(1) O2 2582(3) 9665(1) 1452(1) 12(1) C1 2427(4) 9333(1) 1432(2) 13(1) C2 1203(4) 9200(1) 1086(2) 15(1) C3 1071(5) 8862(1) 1083(2) 20(1) C4 2108(5) 8656(1) 1382(2) 23(1) C5 3314(5) 8788(1) 1682(2) 17(1) C6 3497(4) 9127(1) 1719(2) 14(1) C7 4837(4) 9253(1) 2056(2) 13(1) C8 6121(4) 9137(1) 1907(2) 16(1) C9 7350(5) 9254(1) 2231(2) 18(1) C10 7347(4) 9492(1) 2699(2) 17(1) C11 6097(4) 9614(1) 2870(2) 14(1) C12 4840(4) 9484(1) 2555(2) 11(1) C13 6088(4) 9853(1) 3405(2) 14(1) C14 6915(5) 9786(1) 3977(2) 22(1) C15 6976(5) 10001(1) 4482(2) 35(1) C16 6226(5) 10291(1) 4419(2) 31(1) C17 5398(5) 10377(1) 3861(2) 21(1) C18 5313(4) 10148(1) 3342(2) 11(1) C19 111(4) 9420(1) 700(2) 16(1) C20 1170(4) 9224(1) 411(2) 25(1) C21 798(5) 9576(1) 146(2) 19(1) C22 428(4) 9694(1) 1110(2) 22(1) C23 4570(5) 10702(1) 3807(2) 21(1) C24 3016(5) 1 0632(1) 3700(2) 28(1) C25 4985(5) 10917(1) 3266(2) 31(1) C26 4858(5) 10902(1) 4425(2) 38(1) C27 1896(4) 10314(1) 1940(2) 12(1) C28 497(4) 10411(1) 2090(2) 13(1)

PAGE 274

274 Table A 26. Continued Atom x y z U(eq) C29 14(4) 10308(1) 2654(2) 22(1) C30 1301(5) 10398(1) 2794(2) 26(1) C31 2141(5) 10587(1) 2374(3) 29(1) C32 1691(5) 10691(1) 1811(3) 28(1) C33 376(4) 10602(1) 1670(2) 20(1) C34 2613(4) 10471(1) 1517(2) 15(1) C35 3984(4) 10374(1) 1314(2) 12(1) C36 4525(4) 10606(1) 841(2) 12(1) C37 4697(4) 10936(1) 988(2) 20( 1) C38 5209(5) 11148(1) 557(2) 24(1) C39 5534(5) 11035(1) 23(2) 25(1) C40 5366(4) 10706(1) 173(2) 22(1) C41 4858(4) 10494(1) 255(2) 19(1) C42 4697(4) 10108(1) 1543(2) 11(1) C43 6079(4) 9985(1) 1384(2) 15(1) C44 3469(4) 9593(1) 2748(2) 11(1) C45 2701(4) 9 423(1) 3249(2) 16(1) C46 1236(5) 9332(1) 2944(2) 28(1) C47 3462(5) 9117(1) 3513(3) 36(1) C48 2577(5) 9659(1) 3808(2) 29(1) ________________________________________________________________________________

PAGE 275

275 Table A 27 Bond lengths (in ) for 18A Bond Len gth Bond Length W1 C44 1.884(4) C17 C18 1.431(6) W1 O2 1.972(3) C17 C23 1.546(6) W1 O1 1.982(3) C19 C20 1.534(6) W1 C27 2.062(4) C19 C22 1.541(6) W1 C42 2.070(4) C19 C21 1.546(6) W1 C12 2.456(4) C23 C24 1.519(6) W1 C34 2.585(4) C23 C25 1.526(6) W1 C35 2.627(4) C23 C26 1.530(6) O1 C18 1.345(5) C27 C34 1.354(6) O2 C1 1.360(5) C27 C28 1.480(5) C1 C6 1.408(6) C28 C33 1.385(6) C1 C2 1.418(6) C28 C29 1.392(6) C2 C3 1.385(6) C29 C30 1.389(6) C2 C19 1.538(6) C30 C31 1.364( 7) C3 C4 1.395(6) C31 C32 1.378(7) C4 C5 1.365(6) C32 C33 1.388(6) C5 C6 1.393(6) C34 C35 1.495(5) C6 C7 1.490(6) C35 C42 1.342(5) C7 C8 1.399(6) C35 C36 1.513(6) C7 C12 1.409(6) C36 C37 1.385(6) C8 C9 1.381(6) C36 C41 1.387(6) C9 C10 1.382(6) C37 C38 1.388(6) C10 C11 1.395(6) C38 C39 1.376(6) C11 C12 1.414(6) C39 C40 1.378(6) C11 C13 1.488(6) C40 C41 1.380(6) C12 C44 1.500(5) C42 C43 1.502(5) C13 C14 1.388(6) C44 C45 1.526(5) C13 C18 1.413(5) C45 C47 1.520(6) C14 C15 1.372(6) C45 C46 1.527(6) C15 C16 1.383(7) C45 C48 1.537(6) C16 C17 1.382(6)

PAGE 276

276 Table A 28. Bond angles (in deg) for 18A Bond Angle Bond Angle C44 W1 O2 91.80(15) C14 C15 C16 119.9(5) C44 W1 O1 91.62(15) C17 C16 C15 122.7(5) O2 W1 O1 166. 74(11) C16 C17 C18 117.2(4) C44 W1 C27 133.91(17) C16 C17 C23 121.4(4) O2 W1 C27 93.63(14) C18 C17 C23 121.4(4) O1 W1 C27 93.22(14) O1 C18 C13 121.9(4) C44 W1 C42 131.03(16) O1 C18 C17 117.9(4) O2 W1 C42 84.37(13) C13 C18 C17 120.2(4) O1 W1 C42 83.72 (13) C20 C19 C2 112.1(3) C27 W1 C42 95.06(16) C20 C19 C22 106.6(3) C44 W1 C12 37.59(15) C2 C19 C22 112.5(4) O2 W1 C12 87.17(12) C20 C19 C21 108.5(4) O1 W1 C12 87.73(13) C2 C19 C21 107.9(3) C27 W1 C12 171.50(15) C22 C19 C21 109.2(3) C42 W1 C12 93.44(1 5) C24 C23 C25 110.0(4) C44 W1 C34 165.21(15) C24 C23 C26 107.4(4) O2 W1 C34 91.30(12) C25 C23 C26 107.0(4) O1 W1 C34 88.65(12) C24 C23 C17 110.1(4) C27 W1 C34 31.39(14) C25 C23 C17 111.4(4) C42 W1 C34 63.69(14) C26 C23 C17 110.7(4) C12 W1 C34 157.11 (13) C34 C27 C28 124.7(4) C44 W1 C35 161.34(15) C34 C27 W1 96.1(3) O2 W1 C35 87.63(12) C28 C27 W1 139.1(3) O1 W1 C35 85.05(12) C33 C28 C29 118.2(4) C27 W1 C35 64.71(14) C33 C28 C27 121.1(4) C42 W1 C35 30.37(14) C29 C28 C27 120.8(4) C12 W1 C35 123.79( 13) C30 C29 C28 120.7(5) C34 W1 C35 33.32(12) C31 C30 C29 120.1(5) C18 O1 W1 130.5(2) C30 C31 C32 120.3(4) C1 O2 W1 129.5(3) C31 C32 C33 119.8(5) O2 C1 C6 120.4(4) C28 C33 C32 120.9(5) O2 C1 C2 118.5(4) C27 C34 C35 127.3(4) C6 C1 C2 121.0(4) C27 C34 W1 52.5(2)

PAGE 277

277 Table A 28. Continued Bond Angle Bond Angle C3 C2 C1 116.9(4) C35 C34 W1 74.9(2) C3 C2 C19 121.3(4) C42 C35 C34 123.0(4) C1 C2 C19 121.7(4) C42 C35 C36 122.6(4) C2 C3 C4 122.3(4) C34 C35 C36 114.3(4) C5 C4 C3 120.0(4) C42 C35 W1 51.2(2) C4 C5 C6 120.7(4) C34 C35 W1 71.8(2) C5 C6 C1 119.0(4) C36 C35 W1 173.4(3) C5 C6 C7 117.7(4) C37 C36 C41 118.9(4) C1 C6 C7 123.2(4) C37 C36 C35 120.1(4) C8 C7 C12 118.2(4) C41 C36 C35 121.0(4) C8 C7 C6 121.4(4) C36 C37 C38 120.0(4) C12 C7 C6 120.4(4 ) C39 C38 C37 120.5(4) C9 C8 C7 120.4(4) C38 C39 C40 119.7(4) C8 C9 C10 121.1(4) C39 C40 C41 119.9(4) C9 C10 C11 120.8(4) C40 C41 C36 120.9(4) C10 C11 C12 117.9(4) C35 C42 C43 128.2(4) C10 C11 C13 120.9(4) C35 C42 W1 98.4(3) C12 C11 C13 121.0(4) C43 C42 W1 133.4(3) C7 C12 C11 121.5(4) C12 C44 C45 124.9(4) C7 C12 C44 118.6(4) C12 C44 W1 92.4(3) C11 C12 C44 119.9(4) C45 C44 W1 142.7(3) C7 C12 W1 108.7(3) C47 C45 C44 111.7(3) C11 C12 W1 107.5(3) C47 C45 C46 109.6(4) C44 C12 W1 50.0(2) C44 C45 C46 1 09.1(3) C14 C13 C18 119.4(4) C47 C45 C48 108.3(4) C14 C13 C11 118.1(4) C44 C45 C48 109.6(4) C18 C13 C11 122.5(4) C46 C45 C48 108.6(4) C15 C14 C13 120.8(4)

PAGE 278

278 Table A 29. Aniso tropic displacement parameters ( 2 x 10 3 ) for 18A The anisotropic displacem ent factor exponent takes the form: 2 2 [ h 2 a* 2 U 11 + ... + 2 h k a* b* U 12 ]. Atom U 11 U 22 U 33 U 23 U 13 U 12 W1 10(1) 12(1) 11(1) 1(1) 2(1) 2(1) O1 15(2) 14(2) 10(2) 4(1) 1(1) 0(1) O2 11(2) 10(2) 16(2) 1(1) 1(1) 0(1) C1 13(2) 16(2) 10(2) 2(2) 5(2) 0(2) C2 16(2) 17(2) 13(3) 2( 2) 4(2) 0(2) C3 19(2) 20(3) 20(3) 1(2) 1(2) 4(2) C4 33(3) 11(2) 25(3) 2(2) 1(2) 7(2) C5 23(3) 15(2) 13(3) 1(2) 0(2) 2(2) C6 16(2) 17(2) 10(2) 3(2) 3(2) 2(2) C7 15(2) 11(2) 13(3) 7(2) 3(2) 4(2) C8 21(2) 14(2) 15(3) 4(2) 7(2) 5(2) C9 17(2) 18(2) 21(3) 6(2) 5(2) 6(2) C10 12(2) 19(3) 19(3) 3(2) 1(2) 1(2) C11 16(2) 13(2) 10(2) 3(2) 0(2) 4(2) C12 12(2) 14(2) 8(2) 5(2) 4(2) 3(2) C13 9(2) 18(2) 15(3) 2(2) 4(2) 2(2) C14 19(2) 24(3) 24(3) 2(2) 1(2) 2(2) C15 38(3) 47(4) 1 6(3) 4(2) 11(2) 9(3) C16 35(3) 37(3) 19(3) 10(2) 4(2) 5(3) C17 17(2) 28(3) 18(3) 3(2) 2(2) 2(2) C18 8(2) 10(2) 15(3) 1(2) 2(2) 3(2) C19 15(2) 17(2) 17(3) 1(2) 1(2) 1(2) C20 17(2) 26(3) 30(3) 1(2) 6(2) 1(2) C21 24(3) 19(2) 14(3 ) 0(2) 1(2) 3(2) C22 15(2) 27(3) 24(3) 5(2) 2(2) 2(2) C23 21(3) 23(3) 20(3) 9(2) 4(2) 3(2) C24 25(3) 28(3) 33(3) 4(2) 11(2) 3(2) C25 32(3) 20(3) 45(4) 5(2) 17(3) 3(2) C26 38(3) 38(3) 38(4) 23(3) 2(3) 10(3) C27 12(2) 9(2) 16(3) 0(2) 2(2) 2(2) C28 12(2) 13(2) 13(3) 4(2) 1(2) 1(2) C29 17(3) 29(3) 20(3) 4(2) 5(2) 2(2) C30 19(3) 36(3) 26(3) 2(2) 12(2) 2(2) C31 12(2) 34(3) 44(4) 8(3) 13(2) 0(2) C32 13(2) 26(3) 45(4) 2(2) 1(2) 6(2) C33 17(2) 20(3) 24(3) 1(2) 1(2) 0 (2) C34 13(2) 15(2) 17(3) 0(2) 1(2) 4(2) C35 13(2) 14(2) 8(2) 3(2) 4(2) 0(2) C36 8(2) 15(2) 13(3) 5(2) 0(2) 4(2) C37 19(2) 21(3) 21(3) 2(2) 5(2) 1(2)

PAGE 279

279 Table A 29. Continued Atom U 11 U 22 U 33 U 23 U 13 U 12 C38 30(3) 16(3) 28(3) 2(2) 9(2) 4( 2) C39 25(3) 30(3) 20(3) 7(2) 6(2) 5(2) C40 19(2) 34(3) 14(3) 1(2) 4(2) 2(2) C41 23(3) 16(2) 19(3) 1(2) 5(2) 0(2) C42 10(2) 10(2) 13(2) 6(2) 5(2) 5(2) C43 17(2) 13(2) 17(2) 0(2) 3(2) 2(2) C44 11(2) 15(2) 8(2) 0(2) 2(2) 2(2) C45 12(2 ) 21(2) 14(3) 6(2) 2(2) 0(2) C46 19(3) 38(3) 28(3) 8(2) 7(2) 8(2) C47 32(3) 37(3) 41(4) 24(3) 18(3) 10(3) C48 34(3) 42(3) 15(3) 1(2) 12(2) 9(3)

PAGE 280

280 Figure A 140 Molecular structure of 19 with ellipsoids presented at 50% probability and hydro gen atoms removed for clarity. X Ray experimental for 19 : X Ray Intensity data were collected at 100 K on a Bruker DUO diffractometer using MoK radiation ( = 0.71073 ) and an APEXII CCD area detector. Raw data frames were read by program SAINT 1 and integrated using 3D profiling algorithms. The resulting data were reduced to produce hkl reflections and their intensities and estimated standar d deviations. The data were corrected for Lorentz and

PAGE 281

281 polarization effects and numerical absorption corrections were applied based on indexed and measured faces. The structure was solved and refined in SHELXTL6.1, using full matrix least squares refinem ent. The non H atoms were refined with anisotropic thermal parameters and all of the H atoms were calculated in i dealized positions and refined riding on their parent atoms. The THF coordinated ligand is wholly disordered and refined in two parts with their site occupatio n factors dependently refined. In addition to the complex, there is a half pentane solvent molecu le in the asymmetric unit disorder ed around an inversion center. The proton on C30 was obtained from a Difference Fourier map and refined f reely. In the final cycle of refinement, 8550 reflections (of which 7605 are observed with I > 2 (I)) were used to refine 477 parameters and the resulting R 1 wR 2 and S (goodness of fit) were 1.57 %, 3.96 % and 1.034 respectively. The refinement was carried out by minimizing the wR 2 function using F 2 rather than F values. R 1 is calculated to provide a reference to the conventional R value but its function is not minimized.

PAGE 282

28 2 Table A 30. Crystal data and structure refinement for 19 Identification code mcg10 Empirical formula C39 H48 O5 W 0.5(C5 H12) Formula weight 816.70 Temperatu re 100(2) K Wavelength 0.71073 Crystal system Monoclinic Space group P2 1 /c a = 10.7096(5) = 90 b = 15.4214(7) c = 22.8399(11) Volume 3726.4(3) 3 Z 4 Density (calculated) 1.456 Mg/m 3 Absorption coefficient 3.142 mm 1 F(000) 1668 Crystal size 0.29 x 0.27 x 0.04 mm 3 Theta range for data collection 1.60 to 27.50. In dex ranges Reflections collected 65701 Independent reflections 8550 [R(int) = 0.0279] Completeness to theta = 27.50 100.0 % Absorption correction Numerical Max. and min. transmission 0.8899 and 0.4627 Refinement method Full m atrix least squares on F 2 Data / restraints / parameters 8550 / 0 / 477 Goodness of fit on F 2 1.034 Final R indices [I>2sigma(I)] R1 = 0.0157, wR2 = 0.0396 [7605] R indices (all data) R1 = 0.0199, wR2 = 0.0407 Largest diff. peak and hole 0.781 and 0.444 e 3 o | |F c o | o 2 F c 2 ) 2 o 2 ) 2 ]] 1/2 o 2 F c 2 ) 2 ] / (n p)] 1/2 2 (F o 2 )+(m*p) 2 +n*p], p = [max(F o 2 ,0)+ 2* F c 2 ]/3, m & n are constants.

PAGE 283

283 Table A 31. Atomic coordinates ( x 10 4 ) and equivalent isotropic di splacement parameters ( 2 x 10 3 ) for 19 U( eq) is defined as one third of the trace of the orthogonalized U ij tensor. Atom x y z U(eq) W1 2747(1) 2025(1) 2627(1) 12(1) O1 3506(1) 2294(1) 3444(1) 15(1) O2 1355(1) 2201(1) 1962(1) 14(1) O3 2007(1) 158(1) 342 4(1) 36(1) O4 1454(2) 587(1) 2488(1) 62(1) C1 4594(2) 2732(1) 3640(1) 15(1) C2 5486(2) 2394(1) 4107(1) 17(1) C3 6564(2) 2889(1) 4289(1) 21(1) C4 6765(2) 3691(1) 4044(1) 21(1) C5 5875(2) 4025(1) 3601(1) 19(1) C6 4784(2) 3552(1) 3392(1) 15(1) C7 3809(2) 394 3(1) 2936(1) 15(1) C8 3364(2) 4776(1) 3027(1) 18(1) C9 2469(2) 5167(1) 2603(1) 21(1) C10 1998(2) 4731(1) 2087(1) 18(1) C11 2415(2) 3897(1) 1982(1) 15(1) C12 3349(2) 3500(1) 2405(1) 14(1) C13 1878(2) 3451(1) 1426(1) 14(1) C14 1822(2) 3893(1) 888(1) 19(1) C1 5 1242(2) 3520(1) 368(1) 23(1) C16 691(2) 2706(1) 385(1) 22(1) C17 708(2) 2237(1) 908(1) 16(1) C18 1333(2) 2617(1) 1437(1) 14(1) C19 5302(2) 1515(1) 4404(1) 19(1) C20 6367(2) 1329(1) 4922(1) 30(1) C21 4055(2) 1508(1) 4660(1) 28(1) C22 5301(2) 777(1) 3955(1 ) 28(1) C23 54(2) 1349(1) 907(1) 19(1) C24 996(2) 1388(2) 1289(1) 39(1) C25 1018(2) 643(1) 1135(1) 32(1) C26 559(2) 1078(1) 281(1) 30(1) C27 2637(2) 699(1) 2688(1) 17(1) C28 1980(2) 82(1) 2840(1) 27(1) C29 1373(2) 910(2) 3614(1) 59(1) C30 3651(2) 924(1 ) 2466(1) 17(1) C31 3949(2) 2643(1) 2258(1) 14(1) C32 5057(2) 2648(1) 1915(1) 17(1) C33 6243(2) 2341(1) 2330(1) 24(1) C34 5311(2) 3560(1) 1684(1) 26(1) C35 4773(2) 2040(1) 1379(1) 24(1) O5 1088(12) 2311(7) 3111(6) 12(1)

PAGE 284

284 Table A 31. Continued Atom x y z U( eq) C36 216(4) 2975(2) 2949(2) 27(1) C37 576(7) 3010(6) 3442(2) 29(1) C38 564(10) 2066(10) 3655(4) 30(2) C39 761(3) 1803(2) 3615(2) 26(1) O5' 937(18) 2149(10) 3046(8) 12(1) C36' 158(5) 1909(3) 2950(2) 28(1) C37' 800(13) 2061(13) 3498(5) 25(2) C38' 355 (9) 2980(8) 3662(3) 26(2) C39' 986(5) 3006(4) 3530(3) 38(2) C40 5605(3) 5062(2) 5201(1) 61(1) C41 6317(4) 5873(2) 5085(2) 78(1) C42 7364(5) 6116(4) 5464(3) 48(1)

PAGE 285

285 Table A 32 Bond lengths (in ) for 19 Bond Length Bond Length W1 C31 1.8995(17) C13 C1 4 1.398(2) W1 O1 1.9603(12) C13 C18 1.414(3) W1 O2 1.9744(12) C14 C15 1.378(3) W1 C30 2.0171(18) C15 C16 1.391(3) W1 C27 2.0549(19) C16 C17 1.393(3) W1 O3 2.277(14) C17 C18 1.415(2) W1 C12 2.4381(17) C17 C23 1.538(3) O1 C1 1.362(2) C19 C22 1.532(3) O2 C18 1.358(2) C19 C20 1.537(3) O5 C28 1.333(2) C19 C21 1.539(3) O5 C29 1.445(3) C23 C24 1.527(3) O4 C28 1.195(3) C23 C25 1.535(3) C1 C6 1.412(2) C23 C26 1.535(3) C1 C2 1.416(2) C27 C30 1.315(2) C2 C3 1.393(3) C27 C28 1 .464(3) C2 C19 1.541(3) C30 H30 0.95(2) C3 C4 1.388(3) C31 C32 1.521(2) C4 C5 1.378(3) C32 C35 1.534(3) C5 C6 1.396(2) C32 C33 1.537(3) C6 C7 1.484(2) C32 C34 1.540(3) C7 C8 1.397(2) O5 C36 1.397(15) C7 C12 1.413(2) O5 C39 1.479(14) C 8 C9 1.390(3) C36 C37 1.513(7) C9 C10 1.382(3) C37 C38 1.534(18) C10 C11 1.394(2) C38 C39 1.493(11) C11 C12 1.417(2) C40 C41 1.509(4) C11 C13 1.479(2) C41 C42 1.359(6) C12 C31 1.530(2)

PAGE 286

286 Table A 33. Bond angles (in deg) for 19 Bond Ang le Bond Angle C31 W1 O1 96.14(6) C14 C13 C18 119.80(16) C31 W1 O2 94.21(6) C14 C13 C11 119.05(16) O1 W1 O2 148.74(5) C18 C13 C11 120.95(15) C31 W1 C30 87.93(7) C15 C14 C13 120.42(18) O1 W1 C30 102.22(6) C14 C15 C16 119.29(17) O2 W1 C30 107.57(6) C15 C16 C17 122.91(17) C31 W1 C27 125.38(7) C16 C17 C18 117.27(17) O1 W1 C27 99.49(6) C16 C17 C23 121.08(16) O2 W1 C27 98.31(6) C18 C17 C23 121.65(16) C30 W1 C27 37.66(7) O2 C18 C13 119.64(15) C31 W1 O3 138.7(3) O2 C18 C17 120.00(16) O1 W1 O3 74.7(3) C13 C18 C17 120.28(16) O2 W1 O5 78.1(3) C22 C19 C20 107.41(16) C30 W1 O5 133.2(3) C22 C19 C21 109.81(16) C27 W1 O5 95.9(3) C20 C19 C21 106.87(16) C31 W1 C12 38.87(6) C22 C19 C2 110.16(15) O1 W1 C12 85.24(5) C20 C19 C2 111.85(15) O2 W1 C12 84.53(5) C21 C 19 C2 110.63(15) C30 W1 C12 126.72(6) C24 C23 C25 110.51(18) C27 W1 C12 164.24(6) C24 C23 C26 107.25(17) O5 W1 C12 99.9(3) C25 C23 C26 106.85(16) C1 O1 W1 128.63(10) C24 C23 C17 109.93(16) C18 O2 W1 130.67(10) C25 C23 C17 110.38(16) C28 O3 C29 115.7( 2) C26 C23 C17 111.86(16) O1 C1 C6 118.84(15) C30 C27 C28 139.93(19) O1 C1 C2 120.49(16) C30 C27 W1 69.61(11) C6 C1 C2 120.57(16) C28 C27 W1 150.44(14) C3 C2 C1 116.99(17) O4 C28 O3 123.33(19) C3 C2 C19 120.47(16) O4 C28 C27 124.7(2) C1 C2 C19 122.53 (16) O3 C28 C27 111.93(18) C4 C3 C2 122.77(17) C27 C30 W1 72.73(12) C5 C4 C3 119.74(17) C27 C30 H30 137.5(12) C4 C5 C6 120.10(18) W1 C30 H30 149.7(12)

PAGE 287

287 Table A 33. Continued Bond Angle Bond Angle C5 C6 C1 119.77(16) C32 C31 C12 119.78(15) C5 C6 C7 1 19.13(16) C32 C31 W1 150.22(14) C1 C6 C7 121.01(15) C12 C31 W1 89.95(10) C8 C7 C12 119.29(16) C31 C32 C35 109.53(15) C8 C7 C6 119.34(16) C31 C32 C33 108.38(15) C12 C7 C6 121.35(16) C35 C32 C33 110.28(16) C9 C8 C7 120.73(17) C31 C32 C34 111.98(15) C10 C9 C8 120.19(18) C35 C32 C34 108.01(16) C9 C10 C11 120.79(17) C33 C32 C34 108.65(16) C10 C11 C12 119.45(16) C36 O5 C39 111.5(10) C10 C11 C13 118.94(16) C36 O5 W1 123.5(8) C12 C11 C13 121.60(16) C39 O5 W1 124.9(8) C7 C12 C11 119.51(16) O5 C36 C37 104. 9(7) C7 C12 C31 120.22(15) C36 C37 C38 103.0(7) C11 C12 C31 119.96(15) C39 C38 C37 101.5(9) C7 C12 W1 109.93(11) O5 C39 C38 104.2(8) C11 C12 W1 111.28(12) C42 C41 C40 120.4(4) C31 C12 W1 51.18(8)

PAGE 288

288 Table A 34. Anisotropic displacemen t parameters ( 2 x 10 3 ) for 19 The anisotropic displacement factor exponent takes the form: 2 [ h 2 a* 2 U 11 + ... + 2 h k a* b* U p ]. Atom U 11 U 22 U 33 U 23 U 13 U 12 W1 11(1) 15(1) 11(1) 0(1) 2(1) 0(1) O1 14(1) 19(1) 13(1) 1(1) 1(1) 1(1) O2 13(1) 18(1) 12(1) 1(1) 3(1) 3(1) O3 32(1) 42(1) 38(1) 23(1) 14(1) 3(1) O4 74(1) 48(1) 54(1) 18(1) 20(1) 43(1) C1 13(1) 20(1) 13(1) 4(1) 4(1) 2(1) C2 16(1) 20(1) 14(1) 1(1) 3(1) 1(1) C3 17(1) 28(1) 17(1) 3(1) 2(1) 2(1) C4 15(1) 27(1) 21(1) 1(1) 2(1) 7(1) C5 20(1) 21(1) 17(1) 0(1) 2(1) 3(1) C6 14(1) 19(1) 13(1) 2(1) 3(1) 1(1) C7 13(1) 17(1) 16(1) 1(1) 4(1) 1(1) C8 20(1) 18(1) 18(1) 4(1) 4(1) 2(1) C9 21(1) 13(1) 28(1) 2(1) 5(1) 1(1) C10 16(1) 17(1) 21(1) 3(1) 1(1) 1(1) C11 14(1) 16(1) 14(1) 2(1) 4(1) 2 (1) C12 13(1) 14(1) 14(1) 2(1) 3(1) 2(1) C13 11(1) 18(1) 14(1) 1(1) 1(1) 3(1) C14 18(1) 19(1) 20(1) 5(1) 2(1) 1(1) C15 28(1) 26(1) 15(1) 6(1) 1(1) 1(1) C16 23(1) 26(1) 14(1) 2(1) 2(1) 3(1) C17 12(1) 18(1) 17(1) 1(1) 0(1) 4(1) C18 10(1 ) 17(1) 15(1) 1(1) 2(1) 3(1) C19 20(1) 21(1) 16(1) 3(1) 1(1) 3(1) C20 32(1) 32(1) 23(1) 11(1) 8(1) 7(1) C21 29(1) 27(1) 29(1) 8(1) 11(1) 2(1) C22 35(1) 22(1) 24(1) 1(1) 1(1) 6(1) C23 20(1) 18(1) 19(1) 2(1) 2(1) 1(1) C24 33(1) 43 (1) 43(1) 16(1) 14(1) 21(1) C25 40(1) 19(1) 31(1) 2(1) 12(1) 3(1) C26 36(1) 25(1) 25(1) 3(1) 12(1) 3(1) C27 17(1) 20(1) 12(1) 2(1) 3(1) 2(1) C28 18(1) 27(1) 35(1) 14(1) 2(1) 3(1) C29 26(1) 70(2) 83(2) 57(2) 16(1) 2(1) C30 18(1) 16(1) 16(1) 0(1) 1(1) 1(1) C31 13(1) 15(1) 12(1) 0(1) 0(1) 0(1) C32 15(1) 18(1) 20(1) 2(1) 6(1) 2(1) C33 14(1) 29(1) 29(1) 2(1) 5(1) 4(1) C34 23(1) 23(1) 36(1) 7(1) 15(1) 0(1) C35 26(1) 27(1) 20(1) 1(1) 10(1) 2(1) O5 9(3) 14(4) 13(3) 7(2) 0(2) 6(2)

PAGE 289

289 Table A 34. Continued Atom U 11 U 22 U 33 U 23 U 13 U 12 C36 28(2) 25(2) 30(2) 7(2) 13(2) 10(2) C37 25(3) 35(3) 28(3) 1(3) 9(3) 6(2) C38 19(4) 44(3) 26(4) 2(4) 5(3) 1(3) C39 28(2) 31(2) 21(2) 10(1) 12(1) 9(2) O5' 9(3) 14(4) 13( 3) 7(2) 0(2) 6(2) C36' 18(2) 38(3) 27(3) 12(2) 7(2) 7(2) C37' 10(4) 35(4) 30(6) 2(5) 9(4) 2(4) C38' 24(4) 36(4) 20(4) 4(4) 10(3) 8(3) C39' 26(3) 39(3) 51(4) 27(3) 18(2) 5(2) C40 104(3) 50(2) 32(1) 9(1) 20(1) 10(2) C41 119(3) 67(2) 57(2) 15(2) 37(2) 10(2) C42 47(3) 44(3) 58(3) 6(3) 28(3) 13(3)

PAGE 290

290 LIST OF REFERENCES (1) Hartwig, J. Organotransition Metal Chemi stry: From Bonding to Catalysis. 2010 (2) Masuda, T. J ournal of Polymer Science Part A Polymer Chemistry 2007 45, 165. (3) Herrmann, W. A.; Cornils, B. Applied Homogeneous Catalysi s with Organometallic Compounds. 2002 (4) Bhaduri, S.; Mukesh, D. Homogeneous Catalysis: Mechani sms and Industrial Applications. 2000 (5) Pommer, H.; Nurrenbach, A. Pu re Appl. Chem. 1975 43, 527. (6) Sacco, A.; Ugo, R.; Moles, A. J. Chem. Soc. A 1966 1670. (7) Biellmann, J. F.; Jung, M. J. Am. Chem. Soc. 1968 90, 1673. (8) Bingham, D.; Webster, D. E.; Wells, P. B. J. Chem. Soc., Dalton Trans. 1974 1514. (9) Bingham, D.; Webster, D. E.; Wells, P. B. J. Chem. Soc., Dalton Trans. 1974 1519. (10) Morrill, T. C.; D'Souza, C. A. Organometallics 2003 22, 1626. (11) Yue, C. J.; Liu, Y.; He, R. J. Mol. Catal. 2006 259, 17. (12) Salvini, A.; Frediani, P.; Piacenti, F. J. Mo l. Catal. 2000 159, 185. (13) Salvini, A.; Piacenti, F.; Frediani, P.; Devescovi, A.; Caporali, M. J. Organomet. Chem. 2001 625, 255. (14) Dallmann, K.; Buffon, R. J. Mol. Catal. 2001 172, 81. (15) Sawyer, K. R.; Glascoe, E. A.; Cahoon, J. F.; Schlegel, J. P.; Harris, C. B. Organometallics 2008 27, 4370. (16) Sivaramakrishna, A.; Mushonga, P.; Rogers, I. L.; Zheng, F.; Haines, R. J.; Nordlander, E.; Moss, J. R. Polyhedron 2008 27, 1911. (17) Verb rugge, P. A.; Heisewolf, G. J. GB, 1975 ; Vol. 1,416,317. (18) Arthurs, M.; Regan, C. M.; Nelson, S. M. J. Chem. Soc., Dalton Trans. 1980 2053. (19) Bergbreiter, D. E.; Parsons, G. L. J. Organomet. Chem. 1981 208, 47. (20) Ohff, A.; Burlakov, V. V.; Rosenthal, U. J. Mol. Catal. 1996 105, 103.

PAGE 291

291 (21) Ziegler, K. ; Holzcamp, E.; Martin, H.; Breil, H. Angew. Chem. 1955 67, 541. (22) Natta, G. J. Polym. Sci. 1955 16, 143. (23) Natta, G. Angew. Chem. 1956 68, 393. (24) Kim, S.; Somorjai, G. Proceedings of the National Academy of Sciences of the United States of Ame rica 2006 103, 15289. (25) Hogan, J. P.; Banks, R. L. U.S., 1958 ; Vol. 2,825,721. (26) Hogan, J. P. J. Polym. Sci. 1970 8, 2637. (27) Karapinka, G. L. U.S., 1973 ; Vol. 3,709,853. (28) Karol, F. J.; Karapinka, G. L.; Wu, C.; Dow, A. W.; Johnson, R. N.; Carrick, W. L. J. Polym. Sci., Part A 1 1972 10, 2621. (29) Groppo, E.; Lamberti, C.; Bordiga, S.; Spoto, G.; Zecchina, A. Chemical Reviews 2005 105, 115. (30) Jensen, V. R.; Angermund, K.; Jolly, P. W.; Borve, K. J. Organometallics 2000 19, 403. (31) M acAdams, L. A.; Buffone, G. P.; Incarvito, C. D.; Rheingold, A. L.; Theopold, K. H. Journal of the American Chemical Society 2005 127, 1082. (32) Dohring, A.; Gohre, J.; Jolly, P. W.; Kryger, B.; Rust, J.; Verhovnik, G. P. J. Organometallics 2000 19, 388 (33) Bhandari, G.; Kim, Y. Y.; Mcfarland, J. M.; Rheingold, A. L.; Theopold, K. H. Organometallics 1995 14, 738. (34) Thomas, B. J.; Noh, S. K.; Schulte, G. K.; Sendlinger, S. C.; Theopold, K. H. Journal of the American Chemical Society 1991 113, 893. (35) Thomas, B. J.; Theopold, K. H. Journal of the American Chemical Society 1988 110, 5902. (36) Vidyaratne, I.; Nikiforov, G. B.; Gorelsky, S. I.; Gambarotta, S.; Duchateau, R.; Korobkov, I. Angewandte Chemie International Edition 2009 48, 6552. (37) G ibson, V. C.; Mastroianni, S.; Newton, C.; Redshaw, C.; Solan, G. A.; White, A. J. P.; Williams, D. J. Journal of the Chemical Society Dalton Transactions 2000 1969. (38) Gibson, V. C.; Maddox, P. J.; Newton, C.; Redshaw, C.; Solan, G. A.; White, A. J. P. ; Williams, D. J. Chemical Communications 1998 1651.

PAGE 292

292 (39) Liang, Y. F.; Yap, G. P. A.; Rheingold, A. L.; Theopold, K. H. Organometallics 1996 15, 5284. (40) Dohring, A.; Jensen, V. R.; Jolly, P. W.; Thiel, W.; Weber, J. C. Organometallics 2001 20, 2234. (41) Rogers, J. S.; Bu, X. H.; Bazan, G. C. Organometallics 2000 19, 3948. (42) Rogers, J. S.; Bazan, G. C. Chemical Communications 2000 1209. (43) Heintz, R. A.; Leelasubcharoen, S.; Liable Sands, L. M.; Rheingold, A. L.; Theopold, K. H. Organometallic s 1998 17, 5477. (44) Sun, M.; Xu, T.; Gao, W.; Liu, Y.; Wu, Q.; Mu, Y.; Ye, L. Dalton Trans. 2011 40, 10184. (45) Xu, T. Q.; Pan, Y.; Lu, X. B. Dalton Transactions 2011 40, 8643. (46) Huang, Y. B.; Jin, G. X. Dalton Transactions 2009 767. (47) Xu, T. Q.; Mu, Y.; Gao, W.; Ni, J. G.; Ye, L.; Tao, Y. C. Journal of the American Chemical Society 2007 129, 2236. (48) Heinemann, O.; Jolly, P. W.; Kruger, C.; Verhovnik, G. P. J. Journal of Organometallic Chemistry 1998 553, 477. (49) Zhang, L.; Gao, W.; Tao, X.; Wu, Q. L.; Mu, Y.; Ye, L. Organometallics 2011 30, 433. (50) Rozenel, S. S.; Chomitz, W. A.; Arnold, J. Organometallics 2009 28, 6243. (51) Zhang, H.; Ma, J.; Qian, Y. L.; Huang, J. L. Organometallics 2004 23, 5681. (52) Ziegler, T.; Schmid, R. Org anometallics 2000 19, 2756. (53) Theopold, K. H.; MacAdams, L. A.; Kim, W. K.; Liable Sands, L. M.; Guzei, I. A.; Rheingold, A. L. Organometallics 2002 21, 952. (54) Jones, D. J.; Gibson, V. C.; Green, S. M.; Maddox, P. J. Chemical Communications 2002 1 038. (55) Ogata, K.; Nakayama, Y.; Yasuda, H. Journal of Polymer Science Part a Polymer Chemistry 2002 40, 2759. (56) Enders, M.; Fernandez, P.; Ludwig, G.; Pritzkow, H. Organometallics 2001 20, 5005. (57) Kotov, V. V.; Avtomonov, E. V.; Sundermeyer, J.; Aitola, E.; Repo, T.; Lemenovskii, D. A. Journal of Organometallic Chemistry 2001 640, 21.

PAGE 293

293 (58) Emrich, R.; Heinemann, O.; Jolly, P.; Kruger, C.; Verhovnik, G. Organometallics 1997 16, 1511. (59) Thomas, B. J.; Noh, S. K.; Schulte, G. K.; Sendlinger, S. C.; Theopold, K. H. J. Am. Chem. Soc. 1991 113, 893. (60) Thomas, B. J.; Theopold, K. H. J. Am. Chem. Soc. 1988 110, 5902. (61) Emrich, R.; Heinemann, O.; Jolly, P. W.; Kruger, C.; Verhovnik, G. P. J. Organometallics 1997 16, 1511. (62) Schulzke, C.; E nright, D.; Sugiyama, H.; LeBlanc, G.; Gambarotta, S.; Yap, G. P. A.; Thompson, L. K.; Wilson, D. R.; Duchateau, R. Organometallics 2002 21, 3810. (63) Ballem, K. H. D.; Shetty, V.; Etkin, N.; Patrick, B. O.; Smith, K. M. Dalton Transactions 2004 3431. ( 64) Schmid, R.; Ziegler, T. Canadian Journal of Chemistry Revue Canadienne De Chimie 2000 78, 265. (65) Ajjou, J. A. N.; Rice, G. L.; Scott, S. L. Journal of the American Chemical Society 1998 120, 13436. (66) Ajjou, J. A. N.; Scott, S. L.; Paquet, V. Jo urnal of the American Chemical Society 1998 120, 415. (67) Ajjou, J. A. N.; Scott, S. L. Journal of the American Chemical Society 2000 122, 8968. (68) Shiotsuki, M.; Sanda, F.; Masuda, T. Polymer Chemistry 2011 2, 1044. (69) Liu, J. Z.; Lam, J. W. Y.; T ang, B. Z. Chemical Reviews 2009 109, 5799. (70) Lam, J. W. Y.; Tang, B. Z. Accounts of Chemical Research 2005 38, 745. (71) Masuda, T.; Thieu, K.; Sasaki, N.; Higashumura, T. Macromolecules 1976 9, 661. (72) Masuda, T.; Sasaki, N.; Higashimura, T. Macr omolecules 1975 8, 717. (73) Masuda, T.; Hasegawa, K.; Higashim.T Macromolecules 1974 7, 728. (74) Hasegawa, K.; Masuda, T.; Higashimura, T. Macromolecules 1975 8, 255. (75) Choi, S.; Gal, Y.; Jin, S.; Kim, H. Chemical Reviews 2000 100, 1645. (76) Shen g, Y. H.; Wu, Y. D. Journal of the American Chemical Society 2001 123, 6662.

PAGE 294

294 (77) Katz, T. J.; Hacker, S. M.; Kendrick, R. D.; Yannoni, C. S. Journal of the American Chemical Society 1985 107, 2182. (78) Katz, T. J.; Lee, S. J. Journal of the American Ch emical Society 1980 102, 422. (79) Mayershofer, M. G.; Nuyken, O. J ournal of Polymer Science Part A Polymer Chemistry 2005 43, 5723. (80) Kaneshiro, H.; Hayano, S.; Masuda, T. Polymer Journal 1999 31, 348. (81) Wallace, K. C.; Liu, A. H.; Davis, W. M.; Schrock, R. R. Organometallics 1989 8, 644. (82) Schrock, R. R.; Luo, S. F.; Lee, J. C.; Zanetti, N. C.; Davis, W. M. Journal of the American Chemical Society 1996 118, 3883. (83) Schrock, R. R.; Luo, S. F.; Zanetti, N. C.; Fox, H. H. Organometallics 199 4 13, 3396. (84) Weiss, K.; Michel, A.; Auth, E.; Bunz, U.; Mangel, T.; Mullen, K. Angewandte Chemie International Edition in English 1997 36, 506. (85) Kloppenburg, L.; Song, D.; Bunz, U. Journal of the American Chemical Society 1998 120, 7973. (86) Bu nz, U. Accounts of Chemical Research 2001 34, 998. (87) Katz, T. J.; Ho, T. H.; Shih, N. Y.; Ying, Y. C.; Stuart, V. I. W. Journal of the American Chemical Society 1984 106, 2659. (88) Weiss, K.; Goller, R.; Loessel, G. Journal of Molecular Catalysis 198 8 46, 267. (89) Mortreux, A.; Petit, F.; Petit, M.; Szymanskabuzar, T. Journal of Molecular Catalysis a Chemical 1995 96, 95. (90) Zhang, W.; Kraft, S.; Moore, J. S. Journal of the American Chemical Society 2004 126, 329. (91) Sarkar, S.; McGowan, K.; K uppuswamy, S.; Ghiviriga, I.; Abboud, K.; Veige, A. Journal of the American Chemical Society 2012 134, 4509. (92) Sarkar, S.; Culver, J. A.; Peloquin, A. J.; Ghiviriga, I.; Abboud, K. A.; Veige, A. S. Angewandte Chemie International Edition 2010 49, 9711 (93) Sarkar, S.; McGowan, K.; Culver, J.; Carlson, A.; Koller, J.; Peloquin, A.; Veige, M.; Abboud, K.; Veige, A. Inorganic Chemistry 2010 49, 5143. (94) Sarkar, S.; Carlson, A.; Veige, M.; Falkowski, J.; Abboud, K.; Veige, A. Journal of the American Ch emical Society 2008 130, 1116.

PAGE 295

295 (95) Sarkar, S.; Abboud, K.; Veige, A. Journal of the American Chemical Society 2008 130, 16128. (96) Koller, J.; Sarkar, S.; Abboud, K.; Veige, A. Organometallics 2007 26, 5438. (97) Jan, M.; Sarkar, S.; Kuppuswamy, S.; G hiviriga, I.; Abboud, K.; Veige, A. Journal of Organometallic Chemistry 2011 696, 4079. (98) Kuppuswamy, S.; Peloquin, A.; Ghiviriea, I.; Abboud, K.; Veige, A. Organometallics 2010 29, 4227. (99) Kuppuswamy, S.; Ghiviriga, I.; Abboud, K.; Veige, A. Organ ometallics 2010 29, 6711. (100) O'Reilly, M.; Del Castillo, T.; Abboud, K.; Veige, A. Dalton Transactions 2012 41, 2237. (101) O'Reilly, M.; Ghiviriga, I.; Abboud, K.; Veige, A. Journal of the American Chemical Society 2012 134, 11185. (102) O'Reilly, M .; Del Castillo, T.; Falkowski, J.; Ramachandran, V.; Pati, M.; Correia, M.; Abboud, K.; Dalal, N.; Richardson, D.; Veige, A. Journal of the American Chemical Society 2011 133, 13661. (103) O'Reilly, M.; Falkowski, J.; Ramachandran, V.; Pati, M.; Abboud, K.; Dalal, N.; Gray, T.; Veige, A. Inorganic Chemistry 2009 48, 10901. (104) Golisz, S.; Labinger, J.; Bercaw, J. Organometallics 2010 29, 5026. (105) Golisz, S. R.; E., B. J. Macromolecules 2009 42, 8751. (106) Korobkov, I.; Gorelsky, S.; Gambarotta, S Journal of the American Chemical Society 2009 131, 10406. (107) Agapie, T.; Day, M.; Bercaw, J. Organometallics 2008 27, 6123. (108) Agapie, T.; Bercaw, J. Organometallics 2007 26, 2957. (109) McGowan, K.; Veige, A. Journal of Organometallic Chemistry 2012 711, 10. (110) McGowan, K.; Abboud, K.; Veige, A. Organometallics 2011 30, 4949. (111) Moulton, C. J.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1976 1020. (112) Crocker, C.; Errington, R. J.; McDonald, W. S.; Odell, K. J.; Shaw, B. L.; Goodfellow, R. J. J. Chem. Soc., Chem. Commun. 1979 498. (113) Errington, R. J.; McDonald, W. S.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1980 2312.

PAGE 296

296 (114) Errington, R. J.; Shaw, B. L. J. Organomet. Chem. 1982 238, 319. (115) Crocker, C.; Empsall, H. D.; Erringto n, R. J.; Hyde, E. M.; McDonald, W. S.; Markham, R.; Norton, M. C.; Shaw, B. L. J. Chem. Soc., Dalton Trans. 1982 1217. (116) Albrecht, M.; Kocks, B. M.; Spek, A. L.; van Koten, G. J. Organomet. Chem. 2001 624, 271. (117) van der Bloom, M. E.; Milstein, D. Chem. Rev. 2003 103, 1759. (118) Slagt, M. Q.; van Zwieten, D. A. P.; Moerkerk, A. J. C. M.; Gebbink, R. J. M. K.; van Koten, G. Coord. Chem. Rev. 2004 248, 2275. (119) Morales, D. M.; Jensen, C. M.; Elsevier: Amsterdam, 2007 (120) Albrecht, M.; van Koten, G. Angewandte Chemie International Edition 2001 40, 3750. (121) van der Boom, M.; Milstein, D. Chemical Reviews 2003 103, 1759. (122) Leis, W.; Mayer, H.; Kaska, W. Coordination Chemistry Reviews 2008 252, 1787. (123) Choi, J.; MacArthur, A.; Bro okhart, M.; Goldman, A. Chemical Reviews 2011 111, 1761. (124) Selander, N.; Szabo, K. Chemical Reviews 2011 111, 2048. (125) Abbenhuis, H. C. L.; Feiken, N.; Haarman, H. F.; Grove, D. M.; Horn, E.; Kooijman, H.; Spek, A. L.; van Koten, G. Angew. Chem. I nt. Ed. 1991 30, 996. (126) Abbenhuis, H. C. L.; Feiken, N.; Grove, D. M.; Jastrzebski, J. T. B. H.; Kooijman, H.; van der Sluis, P.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J. Am. Chem. Soc. 1992 114, 9773. (127) Abbenhuis, H. C. L.; Feiken, N.; Ha arman, H. F.; Grove, D. M.; Horn, E.; Spek, A. L.; Pfeffer, M.; van Koten, G. Organometallics 1993 12, 2227. (128) Donkervoort, J. G.; Jastrzebski, J. T. B. H.; Deelman, B. J.; Kooijman, H.; Veldman, N.; Spek, A. L.; van Koten, G. Organometallics 1997 16 4174. (129) Donkervoort, J. G.; Kronenburg, C. M. P.; Deelman, B. J.; Jastrzebski, J. T. B. H.; Veldman, N.; Spek, A. L.; van Koten, G. J. Organomet. Chem. 1997 547, 349. (130) Donkervoort, J. G.; Vicario, J. L.; Jastrzebski, J. T. B. H.; Gossage, R. A. ; Cahiez, G.; van Koten, G. J. Organomet. Chem. 1998 538, 61.

PAGE 297

297 (131) Brandts, J. A. M.; Kruiswijk, E.; Boersma, J.; Spek, A. L.; van Koten, G. J. Organomet. Chem. 1999 585, 93. (132) Brandts, J. A. M.; Gossage, R. A.; Boersma, J.; Spek, A. L.; van Koten, G. Organometallics 1999 18, 2642. (133) Filippou, A. C.; Schneider, S. Organometallics 2003 22, 3010. (134) Alonso, P. J.; Fornies, J.; Garcia Monforte, M. A.; Martin, A.; Menjon, B.; Rillo, C. Chemistry a European Journal 2002 8, 4056. (135) Noh, S. K. ; Heintz, R. A.; Haggerty, B. S.; Rheingold, A. L.; Theopold, K. H. Journal of the American Chemical Society 1992 114, 1892. (136) Koschmieder, S. U.; Mcgilligan, B. S.; Mcdermott, G.; Arnold, J.; Wilkinson, G.; Hussainbates, B.; Hursthouse, M. B. Journal of the Chemical Society Dalton Transactions 1990 3427. (137) Stavropoulos, P.; Savage, P. D.; Tooze, R. P.; Wilkinson, G.; Hussain, B.; Motevalli, M.; Hursthouse, M. B. Journal of the Chemical Society Dalton Transactions 1987 557. (138) Cardin, C. J.; C ardin, D. J.; Roy, A. Journal of the Chemical Society Chemical Communications 1978 899. (139) Seidel, W.; Burger, I. Zeitschrift Fur Anorganische Und Allgemeine Chemie 1976 426, 155. (140) Muller, J.; Holzinger, W. Angewandte Chemie International Edition in English 1975 14, 760. (141) Mowat, W.; Shortlan.Aj; Hill, N. J.; Wilkinso.G Journal of the Chemical Society Dalton Transactions 1973 770. (142) Mowat, W.; Shortlan.A; Wilkinso.G; Yagupsky, G.; Yagupsky, M.; Hill, N. J. Journal of the Chemical Society Dalton Transactions 1972 533. (143) Gramlich, V.; Pfefferk.K Journal of Organometallic Chemistry 1973 61, 247. (144) Kruse, W. Journal of Organometallic Chemistry 1972 42, C39. (145) Bower, B. K.; Tennent, H. G. Journal of the American Chemical Society 1972 94, 2512. (146) Furstner, A. Chemical Reviews 1999 99, 991. (147) Schrock, R. R.; Parshall, G. W. Chemical Reviews 1976 76, 243. (148) Davidson, P. J.; Lappert, M. F.; Pearce, R. Chemical Reviews 1976 76, 219.

PAGE 298

298 (149) Filippou, A. C.; Schneider, S. ; Ziemer, B. European Journal of Inorganic Chemistry 2002 2928. (150) Nemes, A.; Bakac, A. Inorganic Chemistry 2001 40, 2720. (151) Gould, E. S. Coordination Chemistry Reviews 1994 135, 651. (152) Scott, S. L.; Bakac, A.; Espenson, J. H. Journal of the American Chemical Society 1992 114, 4205. (153) Rahman, M.; Rocek, J. Journal of the American Chemical Society 1971 93, 5455. (154) Wiberg, K. B.; Mukherje.Sk Journal of the American Chemical Society 1971 93, 2543. (155) Schmid, R.; Ziegler, T. Organome tallics 2000 19, 2756. (156) Albahily, K.; Koc, E.; Al Baldawi, D.; Savard, D.; Gambarotta, S.; Burchell, T. J.; Duchateau, R. Angew. Chem. Int. Ed. 2008 47, 5816. (157) Crewdson, P.; Gambarotta, S.; Djoman, M. C.; Korobkov, I.; Duchateau, R. Organometal lics 2005 24, 5214. (158) Gibson, V. C.; Spitzmesser, S. K. Chemical Reviews 2003 103, 283. (159) MacAdams, L. A.; Kim, W. K.; Liable Sands, L. M.; Guzei, I. A.; Rheingold, A. L.; Theopold, K. H. Organometallics 2002 21, 952. (160) Gibson, V. C.; Newton C.; Redshaw, C.; Solan, G. A.; White, A. J. P.; Williams, D. J. European Journal of Inorganic Chemistry 2001 1895. (161) Bazan, G. C.; Rogers, J. S.; Fang, C. C. Organometallics 2001 20, 2059. (162) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew andte Chemie International Edition 1999 38, 428. (163) Theopold, K. H. European Journal of Inorganic Chemistry 1998 15. (164) Theopold, K. H.; Heintz, R. A.; Hoh, S. K.; Thomas, B. J. In Homogenous Transition Metal Catalyzed Reactions; Moser, W. R., Sloc um, D. W., Eds.; American Chemical Society: Washington, D. C., 1992 p 591. (165) McDanie l, M. P. Advances in Catalysis 2010 53, 123. (166) Power, P. P.; Ruhlandtsenge, K.; Shoner, S. C. Inorg. Chem. 1991 30, 5013. (167) Tang, Y. J.; Felix, A. M.; Boro, B. J.; Zakharov, L. N.; Rheingold, A. L.; Kemp, R. A. Polyhedron 2005 24, 1093.

PAGE 299

299 (168) Rees, W. S.; Green, D. M.; Hesse, W. Polyhedron 1992 11. (169) Haaland, A.; Hedberg, K.; Power, P. P. Inorg. Chem. 1984 23, 1972. (170) Evans, D. F. J. Chem. Soc. 1959 2003. (171) Schneider, S.; Filippou, A. C. Inorganic Chemistry 2001 40, 4674. (172) Gao, H. Y.; Liu, X. F.; Tang, Y.; Pan, J.; Wu, Q. Polymer Chemistry 2011 2, 1398. (173) Egorova, O. A.; Tsay, O. G.; Khatua, S.; Huh, J. O.; Churchill, D. G. Inorganic Chemistry 2009 48, 4634. (174) Meier Callahan, A. E.; Gray, H. B.; Gross, Z. Inorganic Chemistry 2000 39, 3605. (175) Odom, A. L.; Mindiola, D. J.; Cummins, C. C. Inorganic Chemistry 1999 38, 3290. (176) Collins, T. J.; Slebodnick, C.; Uffelman, E. S. I norganic Chemistry 1990 29, 3433. (177) Morse, D. B.; Rauchfuss, T. B.; Wilson, S. R. Journal of the American Chemical Society 1988 110, 8234. (178) Srinivasan, K.; Kochi, J. K. Inorganic Chemistry 1985 24, 4671. (179) Herberhold, M.; Kremnitz, W.; Raza vi, A.; Schollhorn, H.; Thewalt, U. Angewandte Chemie International Edition in English 1985 24, 601. (180) Krumpolc, M.; Deboer, B. G.; Rocek, J. Journal of the American Chemical Society 1978 100, 145. (181) Gahan, B.; Garner, D. C.; Hill, L. H.; Mabbs, F. E.; Hargrave, K. D.; Mcphail, A. T. Journal of the Chemical Society Dalton Transactions 1977 1726. (182) Davies, N. R. Reviews of Pure and Applied Chemistry 1967 17, 83. (183) Gauthier, D.; Lindhardt, A. T.; Olsen, E. P. K.; Overgaard, J.; Skrydstrup, T. Journal of the American Chemical Society 2010 132, 7998. (184) Vanalstyne, E. M.; Norman, A. W.; Okamura, W. H. Journal of the American Chemical Society 1994 116, 6207. (185) Sodeoka, M.; Shibasaki, M. Synthesis Stuttgart 1993 643. (186) Sodeoka, M. ; Yamada, H.; Shibasaki, M. Journal of the American Chemical Society 1990 112, 4906.

PAGE 300

300 (187) Sneeden, R. P. A.; Zeiss, H. H. Journal of Organometallic Chemistry 1968 13, 369. (188) Sneeden, R. P. A.; Zeiss, H. H. Journal of Organometallic Chemistry 1968 1 3, 377. (189) Studer, A.; Curran, D. P. Angewandte Chemie International Edition 2011 50, 5018. (190) Nishimura, K.; Yamamoto, A.; Ikeda, S.; Kuribayashi, H. Journal of Organometallic Chemistry 1972 37, 317. (191) Daniele, S.; Hitchcock, P. B.; Lappert, M F.; Nile, T. A.; Zdanski, C. M. Journal of the Chemical Society Dalton Transactions 2002 3980. (192) Meca, L.; Cisarova, I.; Drahonovsky, D.; Dvorak, D. Organometallics 2008 27, 1850. (193) Brison, J.; Debakker, C.; Defay, N.; Geertsevrard, F.; Marchan t, M. J.; Martin, R. H. Bulletin Des Societes Chimiques Belges 1983 92, 901. (194) Granzhan, A.; Ihmels, H.; Mikhlina, K.; Deiseroth, H. J.; Mikus, H. European Journal of Organic Chemistry 2005 4098. (195) Sarkar, S.; Culver, J.; Peloquin, A.; Ghiviriga, I.; Abboud, K.; Veige, A. Angewandte Chemie International Edition 2010 49, 9711. (196) Stahl, N. G.; Salata, M. R.; Marks, T. J. Journal of the American Chemical Society 2005 127, 10898. (197) Chen, E. Y. X.; Marks, T. J. Chemical Reviews 2000 100, 139 1. (198) Deck, P. A.; Beswick, C. L.; Marks, T. J. Journal of the American Chemical Society 1998 120, 1772. (199) Deck, P. A.; Beswick, C. L.; Marks, T. J. Journal of the American Chemical Society 1998 120, 12167. (200) Yang, X. M.; Stern, C. L.; Marks, T. J. Journal of the American Chemical Society 1991 113, 3623. (201) Bibal, C.; Santini, C. C.; Chauvin, Y.; Vallee, C.; Olivier Bourbigou, H. Dalton Transactions 2008 2866. (202) Hawrelak, E. J.; Deck, P. A. Organometallics 2003 22, 3558. (203) Zhou, J M.; Lancaster, S. J.; Walker, D. A.; Beck, S.; Thornton Pett, M.; Bochmann, M. Journal of the American Chemical Society 2001 123, 223.

PAGE 301

301 (204) Courtenay, S.; Stephan, D. W. Organometallics 2001 20, 1442. (205) Antinolo, A.; Carrillo Hermosilla, F.; Ferna ndez Baeza, J.; Garcia Yuste, S.; Otero, A.; Sanchez Prada, J.; Villasenor, E. Journal of Organometallic Chemistry 2000 609, 123. (206) Sun, M. T.; Mu, Y.; Liu, Y.; Wu, Q. L.; Ye, L. Organometallics 2011 30, 669. (207) Junges, F.; Kuhn, M.; dos Santos, A .; Rabello, C.; Thomas, C.; Carpentier, J.; Casagrande, O. Organometallics 2007 26, 4010. (208) Malmberg, A.; Kokko, E.; Lehmus, P.; Lofgren, B.; Seppala, J. V. Macromolecules 1998 31, 8448. (209) Kokko, E.; Lehmus, P.; Leino, R.; Luttikhedde, H. J. G.; Ekholm, P.; Nasman, J. H.; Seppala, J. V. Macromolecules 2000 33, 9200. (210) Wang, W. J.; Yan, D. J.; Zhu, S. P.; Hamielec, A. E. Macromolecules 1998 31, 8677. (211) Xu, J.; Gao, W.; Zhang, Y.; Li, J.; Mu, Y. Journal of Organometallic Chemistry 2007 69 2, 1505. (212) Zhang, Y. T.; Mu, Y.; Lu, C. S.; Li, G. H.; Xu, J. S.; Zhang, Y. R.; Zhu, D. S.; Feng, S. H. Organometallics 2004 23, 540. (213) Eisch, J. J.; Caldwell, K. R.; Werner, S.; Kruger, C. Organometallics 1991 10, 3417. (214) Mehrkhodavandi, P.; Schrock, R. R.; Pryor, L. L. Organometallics 2003 22, 4569. (215) Mynott, R.; Fink, G.; Fenzl, W. Angewandte Makromolekulare Chemie 1987 154, 1. (216) Fink, G.; Fenzl, W.; Mynott, R. Zeitschrift Fur Naturforschung Section B a Journal of Chemical Science s 1985 40, 158. (217) Fink, G.; Schnell, D. Angewandte Makromolekulare Chemie 1982 105, 31. (218) Fink, G.; Zoller, W. Makromolekulare Chemie Macromolecular Chemistry and Physics 1981 182, 3265. (219) Nomura, K.; Naga, N.; Miki, M.; Yanagi, K.; Imai, A. Organometallics 1998 17, 2152. (220) Chen, Y. X.; Fu, P. F.; Stern, C. L.; Marks, T. J. Organometallics 1997 16, 5958.

PAGE 302

302 (221) Yang, X. M.; Stern, C. L.; Marks, T. J. Journal of the American Chemical Society 1994 116, 10015. (222) Marks, T. J.; Stevens, J. C. Topics in Catalysis Baltzer, Amsterdam, 1999 ; Vol. 7. (223) Wu, X.; Tamm, M. Beilstein Journal of Organic Chemistry 2011 7, 82. (224) Jyothish, K.; Zhang, W. Angewandte Chemie International Edition 2011 50, 8478. (225) Zhang, W.; Moore, J. Advanced Synthesis & Catalysis 2007 349, 93. (226) Schrock, R.; Czekelius, C. Advanced Synthesis & Catalysis 2007 349, 55. (227) Heeger, A. J. Angewandte Chemie International Edition 2001 40, 2591. (228) MacDiarmid, A. G. Angewandte Chemie International Edition 2001 40, 2581. (229) Shirakawa, H. Angewandte Chemie International Edition 2001 40, 2575. (230) Chiang, C. K.; Fincher, C. R.; Park, Y. W.; Heeger, A. J.; Shirakawa, H.; Louis, E. J.; Gau, S. C.; Macdiarmid, A. G. Physical Review Letters 1977 39, 1098. (231) Shirakawa, H.; Louis, E. J.; Macdiarmid, A. G.; Chiang, C. K.; Heeger, A. J. Journal of the Chemical Society Chemical Communications 1977 578. (232) Moraes, F.; Davidov, D.; Kobayashi, M.; Chung, T. C.; Chen, J.; Heeger, A. J.; Wudl, F. Synthetic M etals 1985 10, 169. (233) Chen, J.; Chung, T. C.; Moraes, F.; Heeger, A. J. Solid State Communications 1985 53, 757. (234) San Jose, B. A.; Matsushita, S.; Moroishi, Y.; Akagi, K. Macromolecules 2011 44, 6288. (235) Yin, S. C.; Xu, H. Y.; Shi, W. F.; Ga o, Y. C.; Song, Y. L.; Wing, J.; Lam, Y.; Tang, B. Z. Polymer 2005 46, 7670. (236) Samuel, I. D. W.; Ledoux, I.; Dhenaut, C.; Zyss, J.; Fox, H. H.; Schrock, R. R.; Silbey, R. J. Science 1994 265, 1070. (237) Tang, B. Z.; Chen, H. Z.; Xu, R. S.; Lam, J. W Y.; Cheuk, K. K. L.; Wong, H. N. C.; Wang, M. Chemistry of Materials 2000 12, 213. (238) Tang, B. Z.; Xu, H. Y.; Lam, J. W. Y.; Lee, P. P. S.; Xu, K. T.; Sun, Q. H.; Cheuk, K. K. L. Chemistry of Materials 2000 12, 1446. (239) Hu, Y.; Shiotsuki, M.; San da, F.; Freeman, B. D.; Masuda, T. Macromolecules 2008 41, 8525.

PAGE 303

303 (240) Hu, Y. M.; Shiotsuki, M.; Sanda, F.; Masuda, T. Chemical Communications 2007 4269. (241) Raharjo, R. D.; Lee, H. J.; Freeman, B. D.; Sakaguchi, T.; Masuda, T. Polymer 2005 46, 6316. (242) Nagai, K.; Masuda, T.; Nakagawa, T.; Freeman, B. D.; Pinnau, I. Progress in Polymer Science 2001 26, 721. (243) Lam, J. W. Y.; Kong, X. X.; Dong, Y. P.; Cheuk, K. K. L.; Xu, K. T.; Tang, B. Z. Macromolecules 2000 33, 5027. (244) Choi, S. K.; Lee, J H.; Kang, S. J.; Jin, S. H. Progress in Polymer Science 1997 22, 693. (245) Kwak, G.; Minakuchi, M.; Sakaguchi, T.; Masuda, T.; Fujiki, M. Chemistry of Materials 2007 19, 3654. (246) Goto, H.; Zhang, H. Q.; Yashima, E. Journal of the American Chemical Society 2003 125, 2516. (247) Aoki, T.; Kokai, M.; Shinohara, K.; Oikawa, E. Chemistry Letters 1993 2009. (248) Moore, J. S.; Gorman, C. B.; Grubbs, R. H. Journal of the American Chemical Society 1991 113, 1704. (249) Zarkesh, R.; Heyduk, A. Organometal lics 2011 30, 4890. (250) Sattler, A.; Parkin, G. Journal of the American Chemical Society 2012 134, 2355. (251) Hardesty, J.; Koerner, J.; Albright, T.; Lee, G. Journal of the American Chemical Society 1999 121, 6055. (252) Kirchner, K.; Calhorda, M.; Schmid, R.; Veiros, L. Journal of the American Chemical Society 2003 125, 11721. (253) Matusiak, R.; Keller, A. Journal of Molecular Catalysis a Chemical 2003 195, 29. (254) Saraev, V.; Kraikivskii, P.; Vilms, A.; Zelinskii, S.; Yunda, A.; Danilovtseva, E.; Kuzakov, A. Kinetics and Catalysis 2007 48, 778. (255) CRC Handbook of Chemistry and Physics; 92 ed.; CRC Press: New York, NY, 2012 (256) Baroni, T.; Heppert, J.; Hodel, R.; Kingsborough, R.; Morton, M.; Rheingold, A.; Yap, G. Organometallics 1996 1 5, 4872.

PAGE 304

304 (257) Hayton, T.; Boncella, J.; Scott, B.; Abboud, K.; Mills, R. Inorg. Chem. 2005 44, 9506. (258) Carlton, L.; Davidson, J.; Ewing, P.; Manojlovicmuir, L.; Muir, K. Journal of the Chemical Society Chemical Communications 1985 1474. (259) Bott, S.; Clark, D.; Green, M.; Mountford, P. Journal of the Chemical Society Dalton Transactions 1991 471. (260) Baroni, T.; Kolesnichenko, V.; Seib, L.; Heppert, J.; Liable Sands, L.; Yap, G.; Rheingold, A. Polyhedron 1998 17, 759. (261) Kong, X.; Lam, J.; T ang, B. Macromolecules 1999 32, 1722. (262) Tang, B.; Poon, W.; Leung, S.; Leung, W.; Peng, H. Macromolecules 1997 30, 2209. (263) Fujita, Y.; Misumi, Y.; Tabata, M.; Masuda, T. Journal of Polymer Science Part a Polymer Chemistry 1998 36, 3157. (264) Si mionescu, C. I.; Percec, V. Journal of Polymer Science Part A Polymer Chemistry 1980 18, 147. (265) Simionescu, C. I.; Percec, V.; Dumitrescu, S. Journal of Polymer Science Part a Polymer Chemistry 1977 15, 2497. (266) Schrock, R.; Luo, S.; Lee, J.; Zane tti, N.; Davis, W. Journal of the American Chemical Society 1996 118, 3883. (267) Kaneshiro, H.; Hayano, S.; Masuda, T. Macromolecular Chemistry and Physics 1999 200, 113. (268) Hayano, S.; Itoh, T.; Masuda, T. Polymer 1999 40, 4071. (269) Hayano, S.; M asuda, T. Macromolecules 1999 32, 7344. (270) Chisholm, M. H.; Folting, K.; Hoffman, D. M.; Huffman, J. C.; Leonelli, J. Journal of the Chemical Society Chemical Communications 1983 589. (271) Bartlett, I.; Connelly, N.; Legge, M.; Martin, A.; Metz, B.; Orpen, A. Chem. Commun. 1996 1877. (272) Canoira, L. J.; Davidson, J. L.; Douglas, G.; Muir, K. W. Journal of Organometallic Chemistry 1989 362, 135. (273) Bray, A.; Mortreux, A.; Petit, F.; Petit, M.; Szymannskabuzar, T Journal of the Chemical Society Chemical Communications 1993 197.

PAGE 305

305 (274) Kishimoto, Y.; Eckerle, P.; Miyatake, T.; Kainosho, M.; Ono, A.; Ikariya, T.; Noyori, R. Journal of the American Chemical Society 1999 121, 12035. (275) Kishimoto, Y.; Eckerle, P.; Miyatake, T.; Ikariya, T.; Noyori, R. Journal of the American Chemical Society 1994 116, 12131. (276) Miyake, M.; Misumi, Y.; Masuda, T. Macromolecules 2000 33, 6636. (277) Saragas, N.; Floros, G.; Paraskevopoulou, P.; Psaroudakis, N.; Koinis, S.; Pitsi kalis, M.; Mertis, K. Journal of Molecular Catalysis a Chemical 2009 303, 124. (278) Xu, K. T.; Peng, H.; Lam, J. W. Y.; Poon, T. W. H.; Dong, Y. P.; Xu, H. Y.; Sun, Q. H.; Cheuk, K. K. L.; Salhi, F.; Lee, P. P. S.; Tang, B. Z. Macromolecules 2000 33, 69 18. (279) Nakako, H.; Misumi, Y.; Masuda, T.; Bencze, L.; Szalai, G. Polymer Journal 1998 30, 577. (280) Misumi, Y.; Tamura, K.; Nakako, H.; Masuda, T. Polymer Journal 1998 30, 581. (281) Masuda, T.; Yamagata, M.; Higashimura, T. Macromolecules 1984 17, 126. (282) Yang, W.; Tabata, M.; Kobayashi, S.; Yokota, K.; Shimizu, A. Polymer Journal 1991 23, 1135. (283) Kanki, K.; Misumi, Y.; Masuda, T. Macromolecules 1999 32, 2384. (284) Saeed, I.; Shiotsuki, M.; Masuda, T. Macromolecules 2006 39, 5347. (285) Misumi, Y.; Masuda, T. Macromolecules 1998 31, 7572. (286) Yao, J.; Wong, W.; Jia, G. Journal of Organometallic Chemistry 2000 598, 228. (287) Kishimoto, Y.; Miyatake, T.; Ikariya, T.; Noyori, R. Macromolecules 1996 29, 5054. (288) Katayama, H.; Yamamur a, K.; Miyaki, Y.; Ozawa, F. Organometallics 1997 16, 4497. (289) Marigo, M.; Millos, D.; Marsich, N.; Farnetti, E. Journal of Molecular Catalysis a Chemical 2003 206, 319. (290) Marigo, M.; Marsich, N.; Farnetti, E. Journal of Molecular Catalysis a Chem ical 2002 187, 169. (291) Farnetti, E.; Filipuzzi, S. Inorganica Chimica Acta 2010 363, 467. (292) Ojwach, S.; Guzei, I.; Darkwa, J.; Mapolie, S. Polyhedron 2007 26, 851.

PAGE 306

306 (293) Sibanyoni, J.; Bagihalli, G.; Mapolie, S. Journal of Organometallic Chemistr y 2012 700, 93. (294) Morawitz, T.; Bao, S.; Bolte, M.; Lerner, H.; Wagner, M. Journal of Organometallic Chemistry 2008 693, 3878. (295) Li, K.; Mohlala, M.; Segapelo, T.; Shumbula, P.; Guzei, I.; Darkwa, J. Polyhedron 2008 27, 1017. (296) Gott, A.; McG owan, P.; Temple, C. Organometallics 2008 27, 2852. (297) Bohm, S.; Parik, P.; Exner, O. New Journal of Chemistry 2006 30, 384. (298) Marcuzzi, F.; Modena, G.; Paradisi, C.; Giancaspro, C.; Speranza, M. Journal of Organic Chemistry 1985 50, 4973.

PAGE 307

307 BIO GRAPHICAL SKETCH Kevin McGow an was born in Garden City, NY. His family moved to Boca Raton, FL when Kevin was eight years old. He attended St. Joan of Arc Catholic School for elementary and middle school before enrolling at St. Andrews School for high scho ol. Here, he excelled in all subjects, including math and science. Upon gra duation, he was honored as the class v aledictorian. Following high school, Kevin went to Duke University. Initially, he enrolled as an engineer, but he became passionate about c hemi stry, so he decided to pursue a degree in c hemistry. In his junior and senior year at Duke, Kevin began teaching science in a local high school. Following his gradu ation from Duke with a B.S. in c hemistry, Kevin decided to teach high school chemistry at Hu tchison School in Memphis, TN. After three years of teaching chemistry, he wanted to continue his studies in chemistry, so he enrolled at the University of Florida as a PhD candidat e in the Chemistry Department. Under the direction of Dr. Adam S. Veige, Ke vin developed the two most highly active catalyst systems ever developed at the Center for Catalysis at UF. He received his PhD from th e University of Florida in the s pring of 2013. Following his PhD journey, he will be pursuing an MBA in his pursuit of de veloping science and technology related startups as an entrepreneur.