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An investigation of some six-membered chelate ring systems

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An investigation of some six-membered chelate ring systems
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Six-membered chelate ring systems
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Morgan, Foy Wyman, 1941-
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English
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x, 113 leaves. : illus. ; 28 cm.

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Chelates ( lcsh )
Chemistry thesis Ph. D ( lcsh )
Dissertations, Academic -- Chemistry -- UF ( lcsh )
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bibliography ( marcgt )
non-fiction ( marcgt )

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Thesis - University of Florida.
Bibliography:
Bibliography: leaf 112.
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Manuscript copy.
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Vita.

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University of Florida
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Copyright Foy Wyman Morgan. Permission granted to the University of Florida to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
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Full Text
AN INVESTIGATION OF SOME
SIX-MEMBERED CHELATE RING SYSTEMS
By
FOY WYMAN MORGAN
A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA August, 1967




ACKNOWLEDGMENTS
The author wishes to express his sincere appreciation to Dr. R. C. Stoufer for his valuable direction and personal friendship during the past four years. I wish also to thank the remaining members of my committee, Drs. R. D. Dresdner, E. H. Hadlock, W. M.
..... D I n fsordner, f or I t d.r ass Is ....
In addition I would like to thank Mr. J. G. Norman for his
loyal support and also to thank the following members of the Department of Chemistry for their understanding help: Mrs. Emma Bowman, Mr. Forest A. Cheves, Miss Mary Helen Hall, Mrs. Evelyn Lea, Mr. William E. Luckhurst, Mr. Joseph W. Miller, Sr., Mr. Morris D. Mixson, and Mr. Trueman Robbins, Jr.
My grateful appreciation is extended to Mrs. Jack Smith for the expert typing of this dissertation and for the personal interest taken by her although she was already heavily committed to other endeavors.
I am grateful to my wife for her continuing invaluable
assistance which has spanned the past eight years and which in the particular case of this dissertation involved typing the rough draft, preparing numerous figures, and providing considerable editorial assistance.
ii




TABLE OF CONTENTS
Page
ACKNOWLEDGMENTS ......... ......................... i.. i
LIST OF TABLES ............. .......................... iv
LIST OF FIGURES ......... ............................. v
INTRODUCTION ........... ........................... i
EXPERIMENTAL PROCEDURES .......... ..................... 3
Apparatus .......... ........................... .. 11
RESULTS AND DISCUSSION ........ ................. ..... ... 13
Complex Salts of Cu(II) ........ .................... ...23
Complex Salts of Co(II) and Ni(II) ..... .............. ... 38
Deprotonated Complexes .......... .................... 58
SUMMARY ........... ............................. ....68
APPENDICES ........... ............................ ... 70
A. VISIBLE SPECTRA ........ ...................... ... 71
B. MAGNETIC MOMENTS .......... ..................... 76
C. INFRARED SPECTRA .......... ..................... 81
Selected Infrared Spectra ..... ............... ...88
BIBLIOGRAPHY ............. ........................... 112
BIOGRAPHICAL SKETCH ........... ....................... 113
iii




LIST OF TABLES
,TALL rage
I. X-Ray Diffraction Data: 20 Values and
Relative Intensities ....... ................... ...53
2. X-Ray Diffraction Data: 26 Values and
Relative Intensities ....... ................... ...54
3. Deprotonated Complexes ....... .................. ...62
4. Spectral Assignments for Some Ni(II) Compounds+
in the Solid State ........ .................... .. 75
5. Room Temperature Magnetic Moments .... ............. ... 77
6. Temperature Dependence of the Molar Susceptibility
and Maghetic Moment of Co(DPK) 2SO 43H20 .......... 80
iv




LIST OF FIGURES
r"Ii lI I'I I t
Flr~iURE rage
1. The infrared spectra of:(a),[PtDPK(DPKH20)]Cl2 22'
(b),[Pt(DPKH20)2]CI2,H20; (c),[PtDPKCI2]; (d),DPK. 15
2. The TGA curves for:(a),[Pt(DPKH20)2]C24H20;
(b),[Pt(DPA) ]Cl 2H 0. 16
2 2 2
3. The TGA curves for:(a),[Cu(DPKH2 0) (H 0) ]CI 2H 0;
(b),[CoDPK(DPKH20)Cl 12H20 18
4. The nature of the proposed steric interaction
across the coordinate plane of [Pt(DPK)2]CI2 . . . 20
5. Prentice-Hall models of:(a), The "boat" configuration formed by di-2-pyridyl ketone hydrate in
complexes; (b),[Pt(DPKH20)2 2+; (c),[PtDPK(DPKH20)]2+. 21
6. The infrared spectra of:(a),[Pt(DPKH20)2]CI24H20;
(b),[Cu(DPKH20)2(H20)2]Cl22H20; (c),[Cu(DPK)2ClI2 . . 24 22202C22'; Y2
7. The positions of the absorption maxima of:(a),
[Cu(DPKH20)2(H20)2]Cl22H2 0; (b),[Cu(DPKH20)2(H20)2
(NO 3)2; (c), Cu(DPKH20)2SO 41/2H20. 26
8. The molar conductivities in water of:(a),[Pd(DPKH20) 2]
Cl 24 20; (b),[Cu(DPKH20)2(H20)2](NO 3)2; (c),
[Cu(DPKH20) 2 (H20) 2]C122H20 28
9. The solution spectra (H20) of [Cu(DPKH20)(H20)2 1
Cl 22H20: (a), 3.8xlO4 m; (b), 3.8x10 m with 3
drops 30% perchloric acid in 30 ml; (c), 3.8xi04
m with 10 drops perchloric acid in 30 ml ....... 29
V




LIST OF FIGURES, Continued FIGURE Page
10. The solution spectra of:(a),[Cu(DPKH20)2(H20)2
Cl 2H 0 in water (2 cm cells) 3.8xl03 m; (b),
22
[Cu(DPKH20) 2 (H20)2](NO )2 in methanol (2 cm cells)
-3
3.Oxl0 m; (c),[Cu(DPKH20)2(H20)2]CI22H20 in
methanol (2 cm cells) 3.6xl0 m. 31
11. The molar conductivities in methanol of:(a),
[Cu(DPK)2Cl12]; (b),[Cu(DPKH2 0)2(H20)2 IC 22H 20;
(c),Cu(DPKH20)2(H20)2(NO 3)2 .. .............. 32
12. The infrared spectra of:(a),Cu(DPK)2(NO 3)2;
2c 32
(b),Cu(DPK) (Cl)2 . .. . . . 34..
2' 2
13. The infrared spectra of:(a),Cu(DPK)2(N03 ) 2
(b),Cu(DPK)2(Cl)2 . . . . . . . . 35
14. The solid-state absorption spectra of:(a),
[Cu(DPK)2ClI2] (diffuse reflectance); (b),[Cu(DPK)2
(NO )2] (Nujol mull); (c),[Cu(DPKH20)2(H20)2]CI22H20
(diffuse reflectance) 37
15. The infrared spectra of:(a),[Cu(DPKH20)2(H20)2]
Cl22H20; (b),[NiDPK(DPKH20 )CI 2]2H20; (c),[CoDPK
(DPKH2 O)Cl 2]2H 20; (d),[Ni(DPK)2Cl2 39
( K 20)C 2]2 2 2.. . .
16. Prentice-Hall models of:(a), trans-[NiDPK(DPKH2 0)
H 0CI]+, with one hydrogen bond shown; (b), cis[NiDPK(DPKH20)Cl2] 41
vi




LIST OF FIGURES, Continued F!GURE Page
17. Diffuse reflectance spectra of:(a),[Ni(DPK)2CI2]
(b),[NiDPK(DPKH20 )CI2]2H20; and solution spectra of:
[NiDPK(DPKH 20)CI 2]2H20, 5xlO-3 m 10 cm cell:(c),
water, (d), methanol 42
18. The molar conductivities in methanol of:(a),[CoDPK
(DPKH20 )CI 2]2H20; (b),[NiDPK(DPKH20 )CI 2]2H20; (c),
Ni(DPK) (NO ) 3H 0; and in water of:(d),Ni(DPK) (NO 3)2
2 3 22' 2 3 2
3H20; (e),[NiDPK(DPKH20 )CI 2]2H20; (f),[CoDPK(DPKH20)
C12]2H20 43
19. The infrared spectra of:(a),[Cu(DPKH20)2(H20) 2 222
Cl 22H 0; (b),[Ni(DPK)2(NO ) ]; (c),Ni(DPK)2(NO )
222 32 2 3 2
2H 0; (d), Ni(DPKH 0) (NO ) H 0. 45
2 2 2 322
20. The TGA curve for: Ni(DPKH 20) 2(NO ) H 20. . . . . 46
21. Nujol mull spectra of:(a),Ni(DPK)2(NO 3)2; (c),
Ni(DPK)2(NO3)22H20; (d), Ni(DPK)2(NO )23H20; and
the solution spectrum (H 0, 5.1xlO-3 m 10 cm cell) of:
2
(b), Ni(DPKH20) 2(NO ) H 0. 47
22. The 'infrared spectra of:(a),[Ni(DPK) (N0 )2 .
(b),[Ni(DPK) Cl2] 49
22
23. The infrared spectra of:(a),Ni(DPK) (NO ) 2H 0;
2 3 2 2
(b), Ni(DPKH20) (NO ) H 20; (c),[Cu(DPKH20)2(H20) 2 22 322 2
Cl 2H 0. . 50
2 2
vii




LIST OF FIGURES, Continued FIGURE Page
24. The infrared spectra of:(a),[Ni(DPK) Cl 2]; 22
(b),[Ni(DPK)2(NCS)2] 12H20; (c),[Co(DPK)2(NCS)2]H 0. . 51
25. The infrared spectra of:(a), Co(DPKH20)2SO H20;
(b), Ni(DPKH20)2SO41/2H20; (c), Cu(DPKH20)2SO4 1/2H20;
(d),[Cu(DPKH 0) (H 0) ]CI 2H 0 55
2222 2 2
26. The TGA curves for:(a), Cu(DPKH20)2SOI l/2H20; (b),
Co(DPKH20)2SO4H20; (c), Ni(DPKH20)2SO41/2H20 . . . 56
27. The molar conductivities in methanol of:(a),
Ni(DPKH20)2SO 41/2H20; (b), Cu(DPKH20)2SO4 1/2H20;
and in water; (c),Ni(DPKH 0) SO 4l/2H 0; (d), S2 4 2
Cu(DPKH20)2S 04 1/2H20; (e),Co(DPKH20) 2So4H20 . . . 59 2+
28. Two views of [Co(DPKH O)(DPKOH)]2 ........... 60
2 2
29. The infrared spectra of:(a), CuDPKO7H20; (b),
Cu (DPKO)2(DPKOH)27H20; (c), Co(DPK)25 1/2H20-3H+;
(d), Co(DPKOH) 1/2H20; (e),Co(DPKH 20) 2SO4 H20 . . . 63
30. Possible structures for:(a),CuDPKO7H20; (b), PtDPKO
2H 0; (c), Cu (DPKO) (DPKOH) 7H 0 65
2 3 2 2 2
31. The molar conductivities in methanol of:(a),
+
Co(DPK) 5 1/2H O-3H ; (b), Co(DPKOH) 21/2H 0; (c),
2 2 2 2
Cu(DPKO) 2 (DPKOH) 27H20 66
32. Reproductions of the visible spectra of:(a),
Aqueous solutions containing cupric chloride and
ethylenediamine (15); (b), Ni(salicylaldehyde)2 (16) 72
viii




LIST OF FIGURES, Continued
FIGURE Page
33. The energy level diagram for Ni(II) in an
octahedral field .. . 74
34. The temperature susceptibility of Co(DPK) SO43H20. . 78
35. The temperature dependence of the magnetic moment
of Co(DPK) 2SO 43H 0 79
242
36. The infrared spectrum of di-2-pyridyl ketone (melt
on NaCI mull plates) 82
37. The infrared spectrum (PtDPKCl 2] (KBr disc) . . . 83
38. The infrared spectra of:(a),[PtDPAClI2] 1; (b),
[Pt(DPA)2]CI 22H 0; (c), Cu(DPA)2Cl2; (d), CuDPACl2 84
2 22 22' '2
39. The infrared spectrum of [Pt(DPKH 0) ]CI 4H 0 (KBr disc) 86
2 22 2
40. The infrared spectrum of [Pt(DPKH 0) 2]Cl 24H 0
2 2 2 2
recrystallized from D20 (KBr disc) 87
41. [Cu(DPKH20)2(H20)2]Cl22H20 89
42. [Cu(DPKH 0) (H 0) ]Cl 22H 0 90
2 22 2 2 2
43. [NiDPK(DPKH2 O)Cl 2]2H20 91
2 2 2
44. [NiDPK(DPKH20 )CI2]2H20 92
45. [Ni(DPK)2 Cl 2 . ... 93
2 2
46. [Ni(DPK) 2Cl2 1 .
4. N(DK2C2.................................. 94
47. Ni(DPKH20)2(NO )2H20 . 95
48. Ni(DPKH20)2(NO3 2 20 96
49. [Ni(DPK)2(NO 3)2 ....... ....................97
50. [Ni(DPK)2(NO 3)2 ........................98
ix




LIST OF FIGURES, Continued
FIGURE Page
51. Ni(DPK) (NO ) 2H 0 99
2 32 2
52. Co(DPKH 0) SO H 0. . 100
2 2 4 2......................0
53. Co(DPKH 0) So H 0 101
2 2 42.........2..........................1
54. [Ni(DPK) (NCS) ]2H 0 ... 102
2 2 2
55. [Ni 2 () (NCS) ]2H 0 . .. . 103
2 2 2
56. Cu3(DPKOH)2(DPKO)27H20 104
2 2
5 C (P H 1/H20 I 06
59. Co(DPKOH) 21/2H2 0 107
32 22
60. CuDPKO7H20 .. . 108
61. CuDPKO7H20 109
62. Co(DPK)25 1/2H20 O-3H. 110
63. Co(DPK)25 1/2H20-3H I
x




INTRODUCTION
Ligands of the type illustrated in Structure I
have received little attention except for di-2-pyridyl amine (X = N, R = H), which exhibits behavior typical of bidentate ligands with coordinate bond formation restricted to the two pyridine nitrogens (1). The acidity of the amine hydrogen has been demonstrated
(2) and the involvement of the deprotonated nitrogen in coordinate bond formation proposed (3). Complexes have been reported which contain from one to three molecules of di-2-pyridyl amine and structural assignments made which embrace the common types, i.e., tetrahedral, planar, and octahedral (1-4).
Ligands in which the bridging atom is a carbon atom (X = C) have not received the attention directed toward di-2-pyridyl amine, perhaps because considerable synthetic difficulties arise since formation of the carbon-carbon bond requires use of the unstable 0(pyridyl Grignard reagent (or oC-lithiopyridine). However, di-2pyridyl ketbne has recently become commercially available.
Di-2-pyridyl ketone (or di-2-pyridyl amine) is formally similar to other bidentate ligands such as acetyl acetone, salicylic acid, 1,8-diaminonaphthalene, imines formed by salicylaldehyde, etc., in that all form six-membered chelate ring systems. However, the resemblance to di-2-pyridyl ketone is closest in the case of acetyl acetone.




2
Both l igands have TT'electron systems and both are of the same symmetry, C2v (d.he C-O bond lengths of acetyl acetone are equivalent in complexes,
H3Cy- C H3 ).
3 QM,0
But of greater importance is the fact that both possess, as do few other ligands of any type, sites susceptible to chemical attack under mild conditions. In the case of complexes of acetyl areton ; the lone ring hydrogen undergoes substitution in a whole series of reactions typical of aromatic systems (halogenation, nitration, suifonation, chloromethylation, etc.) (5). The reactive site in di-2-pyridyl ketone is, of course, the carbonyl group which, in the uncoordinated molecule, might be expected to undergo normal carbonyl reactions (reduction; formation of imines, hydrazones, and ketals; reactions with hydrogen cyanide, Grignard reagents; etc.).
Hydration of the ketone carbonyl, a less common reaction, occurs only to a slight extent and only in aqueous solution (except for f diketones, fluroketones, etc.) with the resulting absence of stable hydrates. The specific property of hydration and the influence of coordination upon the hydration of di-2-pyridyl ketone, together with the physical and chemical nature of the resulting hydrates, constitutes in large part the work described herein. Complexes of three first row transition metal ions [Co(II), Ni(II), and Cu(II)] were isolated and characterized as sulfates, nitrates, chlorides, and thiocyanates. To a lesser degree, the chloride and tartrate salts of the complexes of Pt(II) and Pd(II) were investigated.




EXPERiMENTAL PROCEDURES
Di-2-pyridyl ketone, DPK. The di-2-pyridyl ketone was obtained
I
from Aldrich Chemical Company and used with no further purification.
Di-2-pyridyl amine, DPA. The di-2-pyridyl amine was purchased from Reilley Tar and Chemical Company and was stuhlimd before use
Dichlorodi-2-pyridylamineplatinum(li), [PtDPACl2]. A solution of potassium tetrachloroplatinate(II) (1.0 g, 0.0025 mole) in the minimum amount of water was added to a solution of di-2-pyridyl amine (0.86 g, 0.005 mole) in 25 ml of acetone. The resulting solution was heated on a steam bath, during which time the volume was maintained by adding acetone, until the initial red color had vanished. The yellow precipitate which formed was washed with acetone and diethyl ether and air dried.
Anal. Calcd. for PtC10 H N Cl2: C, 27.47; H, 2.08; N, 9.61. Found: C, 27.30; H, 2.28; N, 9.04. Yield 0.89 g.
Dichlorodi-2-opridylketoneplatinum(Ill, [PtDPKCI ]. The di-2pyridyl ketone complex was prepared by the same method as the di-2pyridyl amine analog, [PtDPACI2].
Anal. Calcd. for PtC H 8N 20CI2: C, 29.35; H, 1.79; N, 6.22. Found: C, 29.26; H, 1.71; N, 6.33.
Dichlorodi-2-pyridlIketonepalladium(II), [PdDPKClI2]. A solution of di-2-pyridyl ketone (0.92 g, 0.005 mole) in N,N-dimethyl formamide (20 ml) was added to a solution of palladium(II) chloride (0.89 g,
3




14
0.005 mole) in warm N,N-dimethyl formamide (75 ml). The solution was allowed to cool andu was Lthen filtered. The yellow solid obtained was washed with acetone and diethyl ether and dried under vacuum.
Anal. Calcd. for PdC,11H8N20C12: C, 36.55; H, 2.23; N, 7.75. Found: C, 36.57; H, 2.22; N, 7.72. Yield approximately 1.3 g.
Bis(di-2-pyridylketonehydrate)platinum(II) chloride monohydrate,
[Pt(DPKH20)2]Cl 2H20. A solution of di-2-pyridyl ketone (0.96 g, 0.005 mole) and potassium tetrachloroplatinate(II) (1.04 g, 0.0025 mole) in water (100 ml) was refluxed for eight hours. The remaining yellow solid was filtered out and discarded. The filtrate was evaporated until crystallization began and subsequently allowed to stand until cool. The white crystalline product was filtered out, washed with acetone and diethyl ether, and dried in vacuo at room temperature. A small portion of the final product was recrystallized from water.
Anal. Calcd. for PtC22H22N405C1 2: C, 38.38; H, 3.22; N, 8.14. Found: C, 38.39; H, 3.29; N, 7.80. Yield 0.38 g.
Bis(di-2-pyridylketonehydrate)palladium(I) chloride monohydrate, [Pd(DPKH20)2]Cl2H20. This yellow material was prepared in a manner similar to that used to prepare [Pt(DPKH20)2]CI 2H20 except that palladium(II) chloride was used and no unreacted material remained after one hour of refluxing.
Anal. Calcd. for PdC22H22N405Cl2: C, 44.06; H, 3.70; N, 9.34. Found: C, 44.28; H, 3.77; N, 9.32. Yield 0.34 g.
Bis(di-2-pyridy lamineplatinum(II) chloride dihydrate, [Pt(DPA)2 Cl 22H 0. A solution of potassium tetrachloroplatinate(II) (1.04 g,




0.0025 mole) and di-2-pyridyl amine (0.855 g, 0.005 mole) in water and acetone (75 ml and 25 ml, respectively) was refluxed for six hours. The tan solid which remained was filtered out and discarded. The filtrate was evaporated until crystallization began and the yellow solid produced was washed with acetone and ether and air dried. A small amount of the final product was recrystallized from water.
Anal. Calcd. for PtC20H22 N 02 C2: C, 37.28; H, 3.44; N, 13.04. Found: C, 36.88; H, 3.42; N, 12.76. Yield 1.3 g.
Bis(di-2-pyridylketonehydrate)platinum(ll) tartrate tetrahydrate,
[Pt(DPKH20)2]C4H4064H20. A saturated aqueous solution (0.20 ml) of potassium tartrate was added over a period of five minutes to a solution of [Pt(DPKH20)2Cl2H20] (0.5 g, 7.3 x 10"4 mole) in water (20 ml). The white crystalline precipitate was filtered out and washed with acetone and diethyl ether.
Anal. Calcd. for PtC26H32N4014: C, 38.09; H, 3.93; N, 6.84. Found: C, 38.16; H, 3.88; N, 6.93.
Bis(di-2-pyridylketonehydrate)_latinumII) tartrate, [Pt(DPKH20)] C4H406. This compound was prepared by heating a sample of [Pt(DPKH20)2] C4H4064H20 for ten minutes at atmospheric pressure at 1400C; a temperature obtained from the thermogravimetric analysis curve.
Anal. Calcd. for PtC26H24N4 010: C, 41.77; H, 3.23; N, 7.50. Found: C, 41.50; H, 3.27; N, 7.20.
Bis(di-2-pyridylketonehydrate)copper(Ill) chloride tetrahydrate,
[Cu(DPKH20)2(H20)2]Cl22H20. A solution of di-2-pyridyl ketone (1.84 g,
0.01 mole) in hot water (30 ml) was added to a solution of copper(II)




6
chloride (0.672 g, 0.005 mole) in water (20 ml). The resulting solution produced dark blue crystals upon standing. The blue material was filtered out, washed with acetone and diethyl ether, and air dried.
Anal. Calcd. for CuC 2H28 N 40 Cl2: C, 43.25; H, 4.60; N, 9.17. Found: C, 43.61; H, 4.65; N, 9.08. Yield 2.0 g.
Bis(di-2-pyridylketonehydrate)copperIll) sulfate hemihydrate,
Cu(urn u2) O 1/2H. The bis sulfate was prepared by the same ethou
2 2 4 2
used to prepare the complex chloride, [Cu(DPKH20)2(H20)2]Cl 2H20. However, the product was heated at 1300C for ten minutes before analysis, (a condition obtained from the TGA curve).
Anal. Calcd. for CuC22H21N 08 1/2S: C, 46.11; H, 3.69; N, 9.78. Found: C, 46.11; H, 3.88; N, 9.66. Yield 2.1 g.
Bisdi-2-pyrEidylketonehydrate)copper Ij nitrate dihydrate,
[Cu(DPKH20)2(H20)2](N03)2. The same method was used to prepare this compound as was used in the preparation of [Cu(DPKH20)2(H20)2]CI22H20.
The product was recrystallized from water.
Anal. Calcd. for CuC22H24N 6 012: C, 42.07; H, 3.85; N, 13.38;
Cu, 10.12. Found: C, 42.22; H, 4.00; N, 13.50; Cu, 10.18. Yield 1.7 g.
Dichlorodi-2-pyridylketonedi-2-pyridylketonehydrate nickel 1l)
dihydrate, [NiDPK(DPKH2 0)CI 2]2H20. This material was prepared by the same method as [Cu(DPKH20)2(H20)2] C122H20.
Anal. Calcd. for NiC22 H 22N 0 Cl 2: C, 47.86; H, 4.02; N, 10.15.
22 22 4 7 2
Found: C, 47.81; H, 3.84; N, 9.80. Yield 1.5 g.
Dichlorobis(di-2-pyridylketone)nickel(II), [Ni(DPK)2Cl2]. The anhydrous chloride was prepared by heating [Ni(DPK)(DPKH2 0)C1212H20




7
at 1800C in air at atmospheric pressure for 15 minutes.
Sr1 for I:r u r C : C, 47. 86; H, 4.02; N. 0. 15.
22"22 4 7 2 78 ,
Found: C, 47.81; H, 3.84; N, 9.80. Yield 1.5 g.
Dichlorobis(di-2-pyr idylketone)nickel(II), [Ni(DPK)2C12]. The anhydrous chloride was prepared by heating [Ni(DPK)(DPKH20 )CI2]2H20 at 1800C in air at atmospheric pressure for 15 minutes.
Anal. Calcd. for NiC22H16N40 2C12: C, 53.06; H, 3.24; N, 11.25. Found: C, 53.36; H, 3.26; N, 11.39. Yield 1.9 g.
Bis(di-2:yridyl ketonehydrate nicke!( _Ijj)nitrate monohydrate,
Ni(DPKH20)2(NO3)2H20. The complex was prepared in this manner described for [Cu(DPKH20) 2 (H20)2] C 122H20.
Anal. Calcd. for NiC22H22N 017: C, 43.66; H, 3.66; N, 13.89. Found: C, 44.08; H, 3.99; N, 13.80.
Bis(di-2-pyridylketone)nickel(II) nitrate dihydrate, Ni(DPK)
2
(NO )22H20. A sample of Ni(DPKH20) (NO )2H20 was heated for ten minutes
3 22 2.'2 32 2
at 1400C in air at atmospheric pressure.
Anal. Calcd. for NiC22H20N6010: C, 45.00; H, 3.43; N, 14.32. Found: C, 45.04; H, 3.55; N, 13.92.
Dinitratobis(di-2-pyridylketone)nickel(II) nitrate, [Ni(DPK)
2
(NO 3)2] The anhydrous nitrate was prepared by heating a sample of Ni(DPKH2 0)2(NO 3) H 20 for 15 minutes at 2200C in air at atmospheric pressure.
Anal. Calcd. for NiC22HI6N608: C, 47.94; H, 2.93; N, 15.25. Found: C, 47.64; H, 2.95; N, 15.14.
Dithiocyanatobis(di-2-pridylketone)nickel(II) dihydrate,




8
[Ni(DPK)2(NCS)2] 12H20. A solution of ammonium thiocyanate (0.76 g,
0.01 mole) in water (50 ml) was added to a stirred solution of di-2pyridyl ketone (1.84 g, .01 mole) and nickel(II) nitrate hexahydrate (1.45 g, 0.005 mole) in water (80 ml). The precipitate was filtered out, washed with acetone and diethyl ether and air dried.
Anal. Calcd. for NiC24H20N604S2: C, 49.76; H, 3.48; N, 14.51. Found: C, 50.22; H, 3.19; N, 14.74. Yield 2.4 g.
Bis(di-2-pyridylketoneh drate)nickel](II) sulfate hemihydrate,
Ni(DPKH20)2SO4 1/2H20. The same method used to prepare [Cu(DPKH20)2 (H20) 2]Cl22H20 was used to prepare the sulfate except that air dried
2 2 2 2
material was additionally dried at 1400C in air for 15 minutes.
Anal. Calcd. for NiC22H21N 08 1/2S: C, 46.50; H, 3.72; N, 9.86; S, 5.64. Found: C, 46.35; H, 3.69; N, 10.16; S, 5.71.
Dichlorodi-2-pyridylketonedi-2-pyridylketonehydrate cobalt(l)dihydrate, [CoDPK(DPKH20)2Cl 2]2H20. The same method was used as was used for [Cu(DPKH20)2(H20)2]CI22H20.
Anal. Calcd. for CoC22H24N406Cl 2: C, 47.84; H, 4.01; N, 10.15. Found: C, 47.72; H, 4.02; N, 10.31. Yield 1.6 g.
Dichlorobis(di-2-pyridylketone)cobalt(ii) chloride, [Co(DPK)
2
Cl2] 1. A sample of [CoDPK(DPKH20)CI12]2H20 was heated in air at atmospheric pressure for ten minutes at 1800C.
Anal. Calcd. for CoC22 H 22N 0 Cl : C, 53.03; H, 3.24; N, 11.25.
--22 22 45 2
Found: C, 53.31; H, 3.27; N, 11.07.
Dithiocya nobisdi-2-pyridylketone)cobalI t(I) monohydrate, [Co(DPK)2(NCS)2]H20. The same procedure was used as in preparing [Ni(DPK) 2(NCS)2 12H 0.




9
Anal. Calcd. for CoC 4H N 0 S : C, 51.33; H, 3.23; N, 14.97.
94 18 6 3 2
Found: C, 51.58; H, 3.0/; N, 14.24. Yield 2.5 g.
Bis(di-2-pyridylketonehydrate)cobalt(IH) sulfate monohydrate.
A method analogous to that used in preparing Cu(DPKH20)2SO4 1/2H20 was employed.
Anal. Calcd. for CoC22 H 22N 0 S: C, 45.76; H, 3.84; N, 9.71; S, 22 22 4 9
5.55; Co, 10.21. Found: C, 46.03; H, 3.75; N, 9.56; S, 5.80; Co, 10.26. Yield 1.9 g.
Cu3(DPKO)2(DPKOH)27H20. To a solution of [Cu(DPKH20)2(H20)2 (N 03)2(3.3 g, 0.005 mole) in boiling water (50 ml) was added to a solution of sodium carbonate (1.7 g, 0.016 mole) in hot water (10 ml). The resulting blue solid was collected, washed with acetone and diethyl ether, and air dried.
Anal. Calcd. for Cu3 C44H48 N 8015: C, 47.20; H, 4.32; N, 10.01;
Cu, 17.03. Found: C, 47.16; H, 4.27; N, 10.24; Cu, 16.74. Yield 2.0 g.
CuDPKO7H20. A solution of di-2-pyridyl ketone (1.84 g, 0.01 mole) and copper(II) nitrate hexahydrate (2.42 g, 0.01 mole) in boiling water (30 ml) was treated with a solution of sodium hydroxide (0.8 g, 0.002 mole) in water (10 ml). A dark blue solution phase separated but converted to a blue solid after standing overnight. The solid material was filtered out, washed with acetone and diethyl ether, and air dried.
Anal. Calcd. for CuC11H22N209: C, 33.89; H, 5.69; N, 7.19; Cu, 16.30. Found: C, 33.71; H, 5.80; N, 7.18; Cl, 0.05; Cu, 16.37. Yield
2.3 g.
PdDPKO2H 0. The palladium compound was prepared by the same




10
method as the copper analog, CuDPKO7H20.
0 r- 0 1
Anal. Calcd. C 3 .6; H, 3 5 ; .1
..r11 12 "2 4 C, 56; H ,
Found: C, 38.42; H, 3.93; N, 8.26. Yield approximately 2 g.
Co(DPKOH)2 1/2H 0. 2.2 g Co(DPKH 0) SO H 0 were dissolved in
22 2 2 42
85 ml of boiling water and the resulting solution was treated with an aqueous solution (20 ml) of sodium carbonate (1.2 g, 0.011 mole). The yellow crystalline solid which formed was washed with acetone and diethyl ether and air dried.
Anal. Calcd. for CoC22H 19N4041/2: C, 56.18; H, 4.07; N, 11.91; Co, 12.53. Found: C, 56.20; H, 4.12; N, 12.20; Co, 12.42; S, none.
+
Co(DPK) 5 1/2H 0-3H 2.0 g Co(DPKH 0) SO H 0 were dissolved in
2 2 2 2 42
hot water (50 ml) and the resulting solution cooled to room temperature. Addition of a solution of sodium hydrogen carbonate (0.58 g, 0.007 ml) in cold water (15 ml) produced a red solution which deposited red-pink crystals on standing in an open vessel for 36 hours.
Anal. Calcd. for CoC22H25N407 1/2: C, 50.48; H, 4.62; N, 10.71; Co, 11.26. Found: C, 50.27; H, 4.82; N, 10.70; Co, 11.14; S, none. Yield approximately 1.2 g.
Dichlorobis di-aEpYidylketonecogpper(ll), [Cu(DPK) Cl ]. The
=_ 2 2
anhydrous copper chloride was prepared by the method used in preparing [Ni(DPK)2C1 2 .
Dinitratobisidi-2-pyridylketone)copper(II, [Cu(DPK) (NO 3)2] See the preparation of [Ni(DPK)2(NO 3 )2




Appra t us
Gouy Balance. Magnetic susceptibility measurements were
made using apparatus previously described (6). Procedures for calibration, temperature control, and cryostat design have also already been described (7).
4Cnortf-nmoto rc A Crr, MrlNA 14s r,-rrinr. seormetear w.c used in obtaining visible and near infrared spectra. Solid-state spectra were obtained using a Cary Model 1411 Diffuse Reflectance Accessory with magnesium carbonate as a reference material. A Perkin-Elmer Corporation Model 237B Infracord recording spectrometer with a scale expansion accessory was used to obtain infrared spectre from 4000 to 625 cm-1. A Sargent Corporation Model SR recorder was used in conjunction with the scale expansion accessory.
Thermoqravimetric Balance. The apparatus used was assembled from a Cahn Model G Electrobalance, a small Kerr furnace, a motordriven transformer, and a Minneapolis-Honeywell temperature bridge. Samples of approximately 0.040 g were suspended in the oven by means of a nichrome wire and weighed on the 0-0.010 g range of the balance using a 0.0.30 g counter weight.
Molecular Weih A_ aratus. A Mechrolab Inc. Model 302 Vapor Pressure Osmometer was used. Several concentrations were run for a particular solute.
Conductance Apparatus. Conductance measurements were made using an Industrial Instruments Model RC-18 Conductivity Bridge and a cell
-l o
with a constant of 1.485 cm- All measurements were made at 25 C;




12
solvent conductivity was measured and subtracted from observed readings.
X-ray Diffraction Apparatus. A Phillips Electronic Instruments Recording Diffractometer equipped with a copper target and a singlecrystal monochromotor was used to obtain powder diffraction data.




RESULTS AND DISCUSSION
The complexes of di-,2-pyridyl ketone involving Co(II), Cu(II), and Ni(II) isolated from aqueous solution contain no more than two molecules of ligand in which one or both ketones contain a molecule of water of hydration (Structure III).
Solid-state composition and cationic structure of these complexes are very dependent upon the nature of the anion present. Only the complexes of copper(II) nitrate and copper(ll) chloride appear to contain ]2+ i h oi tt.Frhr
the simple cation [M(DPKH20)2(H20)2 2+ in the solid state. Further, the bis(di-2-pyridylketonehydrate) complexes exhibit acidic behavior, producing distinct compounds of varying compositions and structures
- 2-when treated with bases such as HCO3, CO 2-, and OH.
3 3
Complexes prepared from Pt(II) and Pd(ll) appear to be somewhat more easily understood than those of the first transition series and are therefore discussed first in order to use certain aspects of their behavior in formulating a model for use in understanding the nature of the remaining complexes.
The di-2-pyridyl ketone complexes prepared from Pt(II) and Pd(II) (and one complex of di-2-pyridyl amine) are listed below:
[Pt(DPKH20) 2C H 0 L4H20 [Pt(DPKH20) IC H 0
S2 4136 2 2 2 4
13




14
[PtCl 2DPK] [Pt(DPKH2 0)2 ]C12 H 0 [Pt(DPA) 2]CI 22H 0
22 2 2 2 2 2
[PdCl 2DPK] [Pd(DPKH 0) ]CI2 H 0 [PtCl DPA]
2 2 2 2 2 2
The symbol "DPK" is used throughout this dissertation to denote di-2pyridyl ketone, "DPKH20" its hydrate, and "DPA" di-2-pyridyl amine. The compounds are of two types, the anhydrous mono(di-2-pyridylketone) complexes (PdCl DPK) and the hydrated bis(di-2-pyridylketone) complexes
2
([Pd(DPKH20)2]CI2H20).
Hydration of the ketone carbonyl should remove the C=0 stretching band found in the infrared spectrum of [PtDPKCl2] (Figure Ic) (1680 cm-1) which in general is quite similar to the spectrum of the free ligand (Figure Id). Indeed the spectrum of [Pt(DPKH 0) I]Cl H 0
2 2 2 2
(Figure lb) exhibits no band at 1680 cm-1 and a general lack of similarity to the free ligand spectrum is evident. In addition, a very broad band is present around 3000 cm-1 in the 0-H and C-H stretching region which is common for hydrogen bonded materials.
If [Pt(Pd)(DPKH20)2]Cl 24H20 is heated to 2500C, a molecule of
ligand and all six water molecules are lost and Pt(Pd)Cl2DPK is formed. The details are displayed in the thermogravimetric analysis curve shown in Figure 2. The weight losses correspond closely to the processes indicated and the infrared spectrum of the material heated to 2200C matches that of [PtCl 2DPK] prepared in aqueous solution. It can be seen in Figure 2 that not all of the water molecules are lost simultaneously. Figure la shows the infrared spectrum of an intermediate monohydrate (prepared by heating at 1200C for ten minutes), and suggests




15
~T h T ~ ~ \ A. 14% '~
I M I
f-l rA h/A
1/1A
z ~
t t~ Ij I II; 4000 3000 2000 1000
FREQUENCY (cm-1)
Figure 1.-The infrared spectra of: (a),[PtDPK(DPKH 2O)1c1
(b),[Pt(DPKH 20) 2ICId 4H 20; (c),[PtDPKCI 1; (d),DPK.




16
b
1 2
1DPK
PtDPKCI
2
100 t o 200 300
Figure 2.-The TGA curves for: (a),IIPt(DPKH 20) ]c1 4H 20; (b),fIPt(DPA) 2]I 2 2H 20.




17
a transient complex containing both a hydrated ligand and an unhydrated ligand; the band at 1680 cm-l supports the existence of the anhydrous ketone and the broad band around 3000 cm the hydrated one. Such mixed complexes are isolated from aqueous solution in complexes of nickel and cobalt (to be discussed later).
The complex, [PtCl DPKJ resists hydration (or even solution)
2
upon prolonged refluxing in water. This fact seems unusual since only hydrated platinum or palladium compounds containing two molecules of ligand are isolated and since attempts at thermal dehydration result in the loss of water followed by immediate loss of a molecule of ligand at the relatively low temperature of 2200C (Figure 2). The analogous chlorides of Ni(II), Cu(II), and Co(II) are readily dehydrated and the anhydrous chlorides are stable over a range of nearly 100C with complete decomposition at almost 3000C (Figure 3).
Inspection of a model (Framework Molecular Models, PrenticeHall, Inc.) of the anhydrous bis(di-2-pyridylketone) complex suggests a reason for its thermal instability and also a reason for the stability of its hydrates. In building the model, the following restrictions were imposed: [11 Pt(II) (or Pd(II)) has only four coordinate bonds in which all nuclei, donor atoms and the metal atom, are located in the same plane (all known Pt(II) and Pd(ll) complexes are four-coordinate and planar); [21 Di-2-pyridyl ketone (or its hydrate) forms only two coordinate bonds involving only the pyridine nitrogens as donors; [31 a conformation of the free ligand allowing planarity of all atoms in




18
3:
cr) Ui
20 100 -tico 200 300
Figure 3.-The TGA curves for:(a),[ Cu(DPKH 2 0) 2 (H 2 0) 2 ICI 2 2H 0;
(b),[CoDPK(DPKH 2 O)CI 2 In 2 0.




19
di-2-pyridyl ketone and therefore maximum resonance interaction of T" symmetry orbitals is favored. Figure 4 shows a sketch of a model of the bis anhydrous complex which indicates that hydrogen atoms on different ligands interact across the'donor-metal plane. Such interaction would either weaken the coordinate bonds by preventing close approach of the donor atoms to the metal atoms or require some sort of distortion from planarity, or both. But a strained condition can be eliminated in either one of two ways: [11 by elimination of one ligand followed by coordination of monodentate ligands which present no steric problems (as in the case of the formation of [PtCl 2DPK] at 2200C); [2] by hydration of one or two ketone carbonyls, which according to the model eliminates all interaction (Figure 5). As is seen in the photograph of the PrenticeHall models (Figure 5a, b), hydration changes the bond angles of the
2
bridging carbon atom from the sp angle to the tetrahedral angle and,as a result, a ''boat'' configuration is possible in which the pyridine rings are canted out of the coordinate plane (a chair configuration would require distortion of the individual pyridine rings). No hydrogen atom interaction is indicated since the two c-hydrogens of one ligand are slanted downward and those of the other upward (Figure 5b). Figure 5c shows the proposed structure for the monohydrate, [Pt(DPKH2 O)DPK]CI2 prepared by heating [Pt(DPKH 20) 2CI2 4H 20 at 1200C for ten minutes. One ketone is hydrated; hence its pyridine rings are not coplanar and their o-hydrogens extend above the anhydrous planar ketone,with the result that no steric interaction between the two ligand molecules is evident.




20
N N
M
N [N
Figure 4.-The nature of the proposed steric interaction
across the coordinate plane of [Pt(DPK) ICl
2 2




21
C
b
Figure 5.-Prentice-Hall models of:(a), The "boat" configuration
formed by di-2-pyridyl ketone hydrate in complexes;
(b),[Pt(DPKH0)2+; (c)[PtDPKDPKH02+
(b),[Pt(DPKH 20Y2 ; (c),[PtDPK(DPKH2O0)]




22
The important conclusion drawn from the above discussion is
that hydration of the ketone carbonyl in complexes of Pd(Il) and Pt(II) occurs because considerable interligand steric interaction destabilizes the ketone carbonyl, which adds a molecule of water with the result that a strain-free, non-interacting, cyclohexane-like boat configuration is formed.
The type of steric interaction discussed in connection with the anhydrous bis(di-2-pyridylketone)platinum(II) chloride is apparently not limited to di-2-pyridyl ketone complexes. The analogous 2,2dipyridine compound, Pt(dipy)2Cl2 is not stable in crystalline Romabut it is reported to exist in solutions containing excess ligand (). 1,10phenanthroline exhibits similar behavior. However, both ligands form solid complexes with Pt(II) and Pd(II) containing two molecules of ligand if the anion involved is C2O PtCl2 or I(8).
In contrast to the bis complex a model of [Pt(Pd)Cl2 DPK] suggests
2
that no steric interaction is present to promote hydration. In addition, electronic stabilization of the ketone form may also be a factor in the absence of hydration in the mono-compounds. One resonance form is shown below which illustrates a possible stabilizing electronic interaction.
0
The complexes prepared from the first row transition metals
considered are of two types: complex metal salts and neutral complexes (containing DPKOH and/or DPKO 2-). Of the two types, the salts exhibit




23
the more regular behavior and are more completely characterized by available methods. Since analysis of their behavior is essential to an understanding of the nature of the neutral complexes, the complex salts will be discussed first,with special attention directed toward influence of the anion present.
_Complex Salts of Cu(I I)
Of all the complex hydrates prepared from salts of copper, nickel, and cobalt shown below, only the nitrate and chloride of copper appear
2+
to contain the simple cation, [Cu(DPKH 0) (H 0) ] in the solid state; all others have too little water for the diaquo cation to exist.
Cu(DPK) Cl 26H 0 Cu(DPK) 2 (NO ) 4H 0 Cu(DPK) 2S 42 1/2H 0
2 22 2 3 22 2 4 2
Ni(DPK)2 Cl 23H20 Ni(DPK)2(NO )23H20 Ni(DPK)2SO 42 1/2H20
Ni(DPK) (NO ) 2H 0 Ni(DPK) (NCS) 2H 0
2 3 22 2 2 2
Co(DPK) Cl 3H 0 Co(DPK) SO 3H 0 Co(DPK) (NCS) H 0
2 2 2 2 4 2 2 2 2
Comparison of the infrared spectra of Cu(DPK) Cl 26H 0 and Pt(DPK) Cl 6H 0
2 2222 2
(Figure 6) suggests that the structure of the complex cation is essentially
the same in both cases, since in this particular system infrared spectra are very sensitive to structural arrangements. As will be seen later, some compounds give infrared spectra characteristic of both hydrated and anhydrous ketones, some lack the broad 0-H stretching absorption
and others show no absorptions characteristic of the hydrated ketone.




24
CbCuDK 2I 0)2( )2II22 ;()[uDK iI2




25
It will be recalled that the cation structure proposed for the platinum compound consists of planar coordination of the four pyridine nitrogens in such a fashion as to produce a boat configuration free from strain and steric interaction (Figbre 5). Such a structure modified to include two trans water molecules is proposed for the solid complexes of copper nitrate and copper chloride. Additional support for this type of tetragonal structure is given by the position of the absorption maxima in the solid state visible spectra (5380A0 for [Cu(DPKH20)2(H 0)] 2 '2 2 2
Cl 22H20 and 5450A0 for [Cu(DPKH20)2(H20) 2 ](N03) and in aqueous solution by both the position of the maxima and the magnitude of the extinction coefficients (5610A, E =37 for [Cu(DPKH20) 2(H20)2]C 22H 20 and 5650A,
E=37 [Cu(DPKH 20) 2(H 20) 2](NO 3) 2). (See the section on visible spectra.) More nearly octahedral structures produce maxima at lower energy and of lower intensity (e.g., 8300A, E =11 for [Cu(H20) 612 ). In Figure 7, the positions of the visible absorption maxima for the copper complexes are arranged according to the energy of the respective transitions. Shifts of varying magnitudes are evident from solid state to solution and a pronounced concentration effect is observed for aqueous solutions of all three complexes. Both the nitrate and the chloride have absorptions of the same energy in the solid state and absorptions of approximately equal energy in the more concentrated aqueous solutions. This parallel spectral behavior indicates that both the nitrate and the chloride have equivalent structures in the solid state and in aqueous solution. An explanation of the spectral concentration dependence of both compounds in aqueous solution is provided by the following observations:




26
-3
o 5x10
-4
o 5x10
6500
-4
4xlO*
6 xO
-4 -4
6000 *5x10 4 x10b4
-3
5 x10 o
-3
5 x10
-4 5 16
9x10 3 4 +5x1 3
3 -5x10 4x10
4x10 5X10 3
4X10 2x103 4 x103
5500
+ + 2( A) (I CI;)N ((:S 04)
a b c
o,inCH30H *,in H20 +,Solid
Figure 7.-The positions of the absorption maxima of:(a),[Cu(DPKH 20)
22
(H20)2]C1 22H20; (b),[Cu(DPKH20)2(H20) 2](NO 3)2; (c),
Cu(DPKH20)2SO4 1/2H20. (The numerical values indicate
concentration in moles per liter.)




27
[1] addition of a strong acid moves the absorption maxima of dilute solutions to higher energies than that of even the concentrated solutions, [2] the conductivity of both complexes approximates that of a di-unielectrolyte (9, P. 339) at high concentrations but deviates markedly toward higher values at low concentration (Figure 8), [31 addition of base to aqueous solutions of either the nitrate or chloride produces an anion-free, deprotonated complex (to be discussed in a later section).
An explanation consistent with the above observations is that
within the solid state of both the chloride and the nitrate salts, the cation, [Cu(DPKH20) 2(H20)2]2, exists which in solution behaves as a weak acid. Thus at low concentrations sufficient conjugate base is present to shift the observed peak to lower energies.
An attendant increase in conductivity in aqueous solution at low concentration is seen for the above complexes in Figure 8. For strong electrolytes, molar conductance is a linear function of C1/2 (C= concentration) and such behavior is observed for [Pd(DPKH20) 2CI 24H20 shown on the same chart. That the palladium complex reveals less acid character suggests that coordination of more than four donor atoms is
important in the ionization process of analogous copper compounds and that the extra donors are possibly deprotonated hydroxyl groups brought into proper spatial relationship by condensation of two or more conjugate bases. Figure 9 shows in a more quantitative fashion the effect of acid on dilute aqueous solutions of [Cu(DPKH 20) 2(H20)2 Id 2 4H 0. A 3.8
24
x 10-4m solution in a ten-centimeter cell (30 ml) exhibits a broad




- MgCI2
250
200
.02 .04 .012 6 .08
Figure 8.-Thempolar conductivities In water of: (a) [Pd(DPKH 20) 23dI 4i 2 0; (b) ,
[CU'(DPKH 0) (H0) ](NO ); (c),[Cu(DPKH 0) (H 0) ICI 2H 0.
2 2(H 2 32 2 2 22 22 0




z
LLJ
801
1 I I I I I
4 5 6 7 8 9 10
WAVELENGTH (A' x 10-3)
Figure 9.-The solution spectra (H20) ,of [Cu(DPKH20)(H20)2]CI 22H20: (a), 3.8xl04 m; (b), 3.8xl04 m with 3 drops 30% perchloric acid in 30 ml; (c), 3.8xl04 m with 10 drops perchloric acid in 30 mi.




30
absorption with a maximum at 6320A. As shown in the figure, addition of 30% perchloric acid in successive amounts of three and ten drops shifts the maximum to nearly 5000A0 and produces a maximum of lower intensity at approximately 7000A, indicating that the acid activity of the complex is surpressed and that the major absorbing species is the diaquobis(di-2-pyridylketonehydrate)copper(II) cation. If perchloric acid in larger amounts is added to more concentrated solutions of the copper nitrate and copper chloride complexes, a peak at about 8300A appears, indicating that the hexaaquo species is formed.
Little effect of concentration on the position of the complex nitrate absorption maximum in methanol solutions is observed; however, the complex chloride absorption is quite concentration-dependent. (Representative spectra are shown in Figure 10.)
No substantial difference between the spectrum of [Cu(DPKH20)2 (H20)2 ](N03)2 in methanol and that of an aqueous solution of [Cu(DPKH20)2(H20)2]CI 24H20 is observed, indicating that methanol solutions of the nitrate contain the same complex as the aqueous solutions or at least a quite similar one. On the other hand, the spectrum of a methanol solution of the chloride is quite distinct, having a much greater width. Such a spectrum is perhaps due to coordination of one chloride ion as suggested by the conductivity data (Figure 11) to form the cation, [Cu(DPKH20)2CIH20]+. Figure 11 shows conductivity data for the chloride and nitrate in methanol together with those for the anhydrous chloride. The behavior of the nitrate approximates that of a di-univalent electrolyte at high concentrations with deviation toward




wC
0
4 5 6 7 8 910
WAVELENGTH (A0 x103
Figure, 10.-The solution speBctra of:(a),LCu(DPKH2 0) 2(H 20) 2ICIl22H2o0 in water (2 cm cells) 3.8xlO- m; (b),
[Cu(DPKH2O0) 2(H 2o) 2] (NO 3) 2in methanol (2 cm cells) 3.OxlO3 m; (c),[Cu(DPKH 2 ) 2(H 2 0) 2
C1 22H 20 in methanol (2 cm cells) 3.6xl0-3 m.




200
0
E
U
7
~2150
Cb fu
C
0
U
100
.02 .04 C/2 .06 .08
Figure 11.-The molar conductivities in methanol of:(a),[Cu(DPIK) 2i .;2 (b),[Cu(DPKH 20)2
2H 2) 2c21420; (c),Cu(DPKH 0) (H 0) (NO
(H0 d2 2!




33
lower molar conductivity at lower concentrations, whereas the behavior of the hydrated chloride is consistent with that of a uni-univalent electrolyte with similar deviation observed at low concentration (9, P. 357-8).
To recapitulate briefly, the cation, [Cu(DPKH20)2]2 exists in
concentrated aqueous solutions and behaves as an acid at low concentrations, producing condensed structures upon ionization. In methanol solutions, however, coordination of chloride ion (and not nitrate ion)
+
occurs (Figure 11) to produce the cation [Cu(DPKH20) 2CIH2 01 or its methanol solvate. Formation of the methanol solvate is probable in the case of the hydrated chloride, since both the hydrated and the anhydrous chloride have almost identical electrical and spectral properties in methanol (Figure 11). Ketal formation is the most probable reaction and would appear to proceed to approximately the same extent with either complexes of the anhydrous ketone or their hydrates.
Unlike their hydrates, the anhydrous copper nitrate ([Cu(DPK)2
(NO)2]) and chloride ([Cu(DPK)2 Cl 2) most likely have cis structures with the anions coordinated in the solid state; a trans structure does not appear reasonable in view of the steric problem discussed earlier. Evidence supporting coordination of the nitrate ion is found in the infrared spectra. Figures 12 and 13 show parts of the infrared spectra for [Cu(DPK)2 Cl 2 ] and [Cu(DPK) 2(NO3 ) 21. The two spectra should be very much alike except for bands produced by the nitrate ion. Indeed, a general similarity is observed in the spectra shown and in other regions
-l -l
not shown (Appendix C), except for two bands at 1310 cm and 1400 cm and a third at 1040 cm-l




ol
U
z
Cr
1400 FREVENCY 13 0 0
Figure 12.-The infrared spectra of:(a),Cu(DPK) 2 (NO 3 )2 (b),ru(DPK) 2 (CI) 2*




35
z
110FRQUNCY(c-' *1000
Figure 13.-The infrared spectra of:(a),Cu(DPK) 2(NO 3) ;(b),Cu(DPK) 2(CI) 2




36
Uncoordinated nitrate has only one band near 1400 cm-l that splits
-1
into two upon coordination, one at 1530-148U cm ', and one at 1290-1250 cm1 (10, p. 161). In addition, a band infrared inactive in NO3 appears as a result of coordinationat 1235-970 cm1l and two other bands of lower intensity are also observed. The spectrum of the anhydrous nitrate (Figures 12 and 13) has three of the bands (1310, 1400, and 1040 cmI) associated with coordinated nitrate, although the splitting of the N-0 stretching band is not as great as reported by Nakamoto (10). However, greater splitting in the anhydrous nickel nitrate (to be discussed later) is observed, perhaps due to a stronger interaction between Ni(II) and nitrate ion (a reasonable conclusion since Ni(II) is less inclined than Cu(II) to form four-coordinate complexes). Two nitrate bands can be assigned but they are of low intensity and the chance of their being obscured by the complicated organic ligand spectrum is quite great.
The visible spectra of the anhydrous copper nitrate and chloride (Figure 14) are almost identical, indicating that chloride, as well as nitrate, is coordinated. Chloride ion and nitrate, although they form relatively weak donor bonds, are not far removed from one another in the spectrochemical series and would be expected to produce equivalent spectra in such a system as that described above.
In attempting to suggest structures for the remaining complex
salts, one observation must be kept in mind: regardless of the anion involved (except for the insoluble thiocyanates), complexes of a particular metal produce identical visible spectra in aqueous solution, no matter how great the variation in the corresponding solid-state spectra. A




Z8
Co
I 1 I I I I I
4 5 6 7 8 9 10
WAVELENGTH (Ao x 103)
Figure 14.-The solid-state absorption spectra of:(a),[Cu(DPK)2Cl2] (diffuse reflectance); (b),
[Cu(DPK)2(N 03)2] (Nujol mull); (c),[Cu(DPKH20)2(H20)2]CI22H20 (diffuse reflectance).
2 3 22 2 22 2 2




38
common coordination polyhedron, therefore, exists in aqueous solution for the complexes of a particular metal and indeed for complexes of all three metals. (See the section on visible spectra.) Conductivity data (Figures 8 and 18) establish that this common species is ionic and that the cation is divalent. In the case of aqueous solutions of the copper chloride and nitrate, a trans-diaquo complex was proposed earlier and in the next section evidence is presented in support of a
trans structure for the analogous nickel cations in aqueous solution.
Having established that all complexes form a common cation in aqueous solution, the problem becomes one of understanding variations in solid-state structure and the following discussions will be directed toward that objective.
Complex Salts of Co(II) and Ni(II)
The chlorides of Ni(II) and Co(II) have the composition, M(DPK)2 Cl 23H 20 and, although prepared in aqueous solution, contain only one hydrated ketone. Figure 15 shows the infrared spectra for the hydrated nickel and cobalt chlorides. The two spectra are identical with a carbonyl band at 1680 cm-I and a broad O-H stretching band occurring near 3000 Cm- In the hydrated chlorides, two strong bands are present
-I
in the region of the highest energy pyridine band (1605 and 1590 cm ).
-l
The band below 1600 cm is associated with the anhydrous ketone as in the spectrum of [Ni(DPK)2 Cl 2, whereas the band above 1600 cm-l is associated with the hydrated ketone as in the spectrum of[Cu(DPKH20) 2] Cl 22H 20.




39
d
c
LLI C-)
X
colt b
<
a
4000 3000 2000 1000
FREQUENCY (cm-1) Figure 15.-The infrared SpeGtra of:(a),(CiA(DPKH 2 0) 2 (H 2 0) 2 ICI 2 2H 2 0;
(b),[NiDPK(DPKH 2 O)CI 2 12H 2 0; (c),(CoDPK(DPKH 2 O)CI 2' 12H 2 0;
(d),[Ni(DPK) 2 Cl 2




4o
Additional areas throughout the chloride spectrum also appear to result from a superpositioning of the spectra of a hydrated ketone and an anhydrous ketone. The reason such a "hemihydrateli should precipitate from water is not completely clear although coordination of chloride ion seems likely, in which case hydration could be prevented by steric hindrance. Molecular models indicate that in the transchloroaquo complex one hydroxyl group would interact with a coordinated chloride ion. A similar interaction is indicated in a dichloro complex containing two hydrated ketones. However, no steric interaction is indicated if one ligand is anhydrous and planar in a trans complex containing one chloride ion and one water molecule as seen in Figure 16a. In Figure 16a, the bottommost group is a chloride ion and the top one a water molecule.
A cis-dichloro configuration with one anhydrous ketone (Figure 16b) is also free of steric interaction and indeed such a structure for the nickel (and cobalt) chloride trihydrate is supported by the visible spectra. As seen in Figure 17, the spectrum of [NiDPK(DPKH20) Cl212H 20 shows a close similarity to the spectrum of [Ni(DPK)2 Cl 2; the latter is expected to have a cis structure as discussed earlier in connection with the copper chloride and nitrate. Both spectra are consistent with approximate octahedral geometry (see the section on visible spectra).
A trans-monochloroaquo structure is unlikely for the solid
nickel (and cobalt) chloride hydrates because methanol solutions containing uni-univalent electrolytes (Figure 18) (and presumably a




41
Figure 16.-Prentice-Hall models of:(a), trans-[NiDPK(DPKH 2 O)H 2 OC11+,
with one hydrogen bond shown; (b), cis-[NiDPK(DPKH 2 O)CI 21.




C-)
C)
< b
5 67 89 10
WAVELENGTH (A' x i0-3)
Figure 17.-Diffuse reflectance spectra of:(a),[Ni(DPK) 2 2;(bNDKPH2 )I 2 20;adslto
spectra of:[NiDPK(DPKH 2O)C 2 12H 20, 5x]0-3 m 10 cm cell:(c), water, (d), methanol.




43
MgC1 Yip 21
--Mg(CNS2,CHOH
3 f
e 20OF d
7
0
E
70
E
4
u
:3
0
CH 01 b
3 100
c 1/2 ..02 .04 .06
FigUre 18.--The molar condLICtiVities in methanol of-(a),[CoDPK(DPKH 2 0) C12)2H 2 0; (b),[NiDPK(DPKH 2 O)cl 2 12H 2 0; (c),Ni(DPK) 2 (NO 3)2 3H20; and in water of:(d),Ni(DPK)2(NO 3 )2 3H 2 0; (e), rNiDPK(DPKfI O)CI 12H 0; (f),[CoDPK(DPKH O)CI 12H 0.
L 2 2 2 2 2 2




44
trans-monochloro complex) exhibit spectra (Figure 17a, b) virtually identical to those of aqueous solutions but quite unlike those exhibited by the solid, [Ni(DPK)2Cl2],and its solid hydrate.
The complex of nickel(II) nitrate and di-2-pyridyl ketone
isolated from aqueous solution is the trihydrate, Ni(DPK)2(NO )23H20. Its infrared spectrum shows no carbonyl band (Figure 19), and only one
-1 -1)
band near 1400 cm- (1385 cm- ) characteristic of uncoordinated nitrate ion (Figures 19 and 20). The corresponding band in the spectrum of
-l
sodium nitrate lies at 1405 cm1. Although a trans-diaquobis(di-2pyridylketonehydrate)nickel(II) cation with ionic nitrate ions would indeed produce an infrared spectrum with the above features, only three of the four requisite water molecules are present in the complex, two of which are involved in the hydration of the two ketone carbonyls. The thermogravimetric analysis curve shown in Figure 20 indicates that only three molecules of water are present and that the trihydrate has an adequate stability range to permit accurate analysis. The solidstate visible spectrum of this complex further confirms that a simple diaquo species does not exist in the solid. As seen in Figure 21, the visible spectrum of the solid is quite distinct from the spectra observed for aqueous solutions of all three nickel complexes, each of which does contain the diaquo cation. Thus, for the solid trihydrate, a polynuclear structure is proposed which would involve coordination of the oxygen atoms of hydroxyl groups as bridging units.
Complete dehydration of the trihydrate, Ni(DPK)2(NO3)23H20,at 2200C produces a complex containing coordinated nitrate ions (Figures




Ad d
A VA j i A A
1( VivN
4w
<
FRQUNC (b -1.
Figure 19.-The infrared spectra of:.(a),[Cu(DPKH 2a) 2(H ? ) 2ICI 2 2 0
(b),[Ni(DPK) 2(No3 ) 21; (c), Ni(DPK) 2(N03 )2 2H 20;
(d), Ni(D-PKH 20) 2(NO3)2 HO20




406
HH-0 2HO0
2
20 100 t2 O 200 300
Figure 20.-The TGA curve for: Ni(DPKHO0) (NiO) H 0.
2 2 32 2




wC
b
01
I I I I I I
5 6 7 8' 9 10
WAVELENGTH (Aox 0l"3)
Figure 21.-Nujol mull spectra of:(a),NI(DPK)2(NO )2; (c), Ni(DPK)2(NO )22H20; (d), Ni(DPK)2(NO )23H20;
and te solution spectrum (H20, 5.1xO3 m cm cell) of: (b), Ni(DPKH20)2(N 3)2H20.
and the solution spectrum (H 20, 5.1x10-3 m 10 cm cell) of: (b), Ni(DPKH2O0) 2(NO 3) 2H 20.




48
19 and 22) characterized by infrared bands at 1450 cm-1, 1285 cm-1, and 1020 cm A cis-dinitrato structure analogous to the copper(ii) nitrate complex is proposed.
An intermediate dihydrate is formed at 1200C (Figure 20),whose infrared spectrum (Figures 18 and 23) shows bands arising from both a hydrated ketone and an anhydrous ketone. In addition, only one
-i
nitrate ion appears to be coordinated (infrared bands at 1440 cm
-l -l
1285 cm and 1020 cm ); the other nitrate ion appears to be uncoordinated (one band at 1380 cm-1). The following structure is therefore reasonable: +
H. H2 ;NO3
ONO2
The visible spectra of the three solid nitrates discussed above show additional complications not observed in the spectrum of the complex nickel chlorides and will be discussed more fully in the later section on visible spectra.
The complex thiocyanates, [Ni(DPK)2(NCS)2]2H20 and [Co(DPK)2
(NCS)2]H20 prepared show no indication of ketone hydration and accordingly a carbonyl band is seen in the infrared spectrum of each compound (Figure 24). The water in each compound produces an absorption at 3400 cm-1 quite distinct from the type of band observed in the complexes of hydrated ketones (Figure 15a). The infrared bands observed for the thiocyanate ion are those characteristic of coordinated thiocyanate linked to the metal through nitrogen, 2075 cm-1 and 800 cm-1. The values observed are within the ranges established by Nakamoto (10, p. 173), 2150-2080 cm- Iand 810-690 cm-1




1400 1300
FREQUENCY (cm-1)
Figure 22.-The infrared spectra of:(a),[NI(DPK) 2(NO 3) 23; (b),[NI(DPK) 2Cl 2.




C
LU
b
a
1400 ~ FREQUENCY (cm' 130
Figure 23.-The infrared spectra of:(a),N!(OPK) 2(NO3)22H 20; (b), Ni(DPKH 2O)2(N0.3 ) 2H 20; (c),[Cu(DPKH 20)2
(2o)2 2 HO




51
b
IH IIIj I
4000 3000 2000 1000
FREQUENCY (cm )
Figure 24.-The infrared spectra of:(a),[Ni(DPK) 2Cl 1;(b),[Ni(DPK)2 (NCS) 212H 2o; (c),[Co(DPK) 2(NCS) 2lu 0.




52
The visible spectrum of the nickel complex is consistent with
an approximately outahedal arrangement of donor atoriL s l etal ion.
The cobalt(tI) thiocyanate is isomorphous to the analogous nickel compound, as seen from the X-ray diffraction data (Table 1).
The three complex sulfates investigated, Cu(DPK)2 SO 42 /2H 20,
Ni(DPK) 2S042 1/2H20, and Co(DPK) 2SO43H20 produce very similar infrared spectra (Figure 25), exhibit similar thermogravimetric behavior (Figure 26), and, according to X-ray diffraction data, are indeed isomorphous (Table 2).
All three compounds were analyzed and investigated after having been heated for ten minutes at 2000 C (Figure 26) to remove a small amount of nonstructural water (the infrared spectrum of the unheated material matched exactly the spectrum of the heated material).
Figure 25 shows the infrared spectra of the three complex
sulfates which differ considerably from the spectrum of [Cu(DPKH 20)2 (H20)2]CI22H20 included for comparison. The broad 0-H band is replaced
-l
by several absorptions spread out over almost 2000 cm the bands arising from C-H linkage are observed in the sulfates, and only two bands are observed near 800 cm in the sulfates, whereas three are present in the complex copper(II) chloride spectrum.
The dissimilarity of the two classes of spectra indicates that the simple diaquobis(di-2-pyridylketonehydrate)meta](II) cation does not exist in the sulfates.




53
Table 1
X-Ray Diffraction Data: 28 Values and Relative intensities
[Co(DPK)2 (NCS)2]H20 [Ni(DPK) 2 (NCS) 212H20
28 Rel. Int. 28 Rel.'Int.
7.38 0.19 7.38 0.24
10.46 0.41 10.46 0.52
12.00 0.42 11.98 0.42
12.28 1.00 12.29 1.00
13.20 0.28 13.20 0.30
16.34 0.35 16.34 0.36
18.76 0.15 18.76 0.12
20.70 0.22 20.80 0.15
23.20 0.49 23.24 0.47
24.00 0.63 24.00 0.63
26.00 0.42 26.02 0.45
26.72 0.50 26.74 0.60
33.40 0.14 33.40 0.10
35.16 0.14 35.16 0.11
39.18 0.10 39.20 0.10




Table 2
X-Ray Diffraction Data: 29 Values and Relative Intensities
Cu(DPK)2SO4 H20 Co(DPK)2SO 4 H20 Ni(DPK)2SO4 H20
20 Rel. Int. 29 Rel. Int. 29 Rel. Int.
9.4 .81 9.7 .675 9.5 .43
12.3 .56 12.6 .59 12.2 .53
12.8 1.00 13.0 1.00 12.5 .80
15.7 .57 15.9 .52 15.5 .48
16.3 .16 16.3 .19
17.8 .18 17.5 .21 17.7 .18
18.1 .17 18.0 .17
19.9 .30 20.2 .38 19.9 .24
20.4 .42 20.8 .38 20.6 .29
22.4 .32 22.8 .37 22.8 .48
23.4 .30 23.6 .31 24.0 .23
24.5 .26 24.8 .33
25.4 .88 25.7 .99 25.2 1.00
25.8 .46 26.1 .37
26.4 .27 26.9 .23 26.6 .19
34.5 .22 35.0 .21 34.2 .13




d
V \f1P1ilY
Cz
%tn
4000 3000 2000 1000
FREQUENCY (cm 224
Figure 25.-The infrared spectra of:(a), Co(DPKH 0) SO H 0; (b),
Ni(DKH 0)2S4 12' ;() Cu(DPKH2O0) 2O s41/11 2 0
(d),[Cu(DPKfH 0) 2(H 20) 2IN 2H1 0.




56
LIJ
20 100 tl co 20030
Figure 26.-The TGA Curves for:(a), Cu(DPKH 2 )2 so 41/2H2O0; (b),
Co(DPKH 0) SO H 0; (c), Ni(DPKH 0) SO 1/2H 0.
2.2 4 2'2 4 2




57
Further evidence that the diaquo cation is not present in the sulfate comes from the fact that the complex cobalt sulfate can be treated with sodium carbonate in boiling aqueous solution to produce a crystalline material of the composition, Co(DPKOH)2 1/2H2 whose infrared spectrum shows considerable similarity to the spectrum of the parent sulfate. The region of the infrared spectrum in which sulfate absorbs accounts for much of the difference between the spectra of the complex cobalt sulfate and that of the resulting deprotonated compound. The deprotonated compound certainly does not contain the diaquobis(di-2-pyridylketonehydrate)cobalt(II) cation, nor does the parent sulfate, since both compounds produce comparable infrared spectra.
A polymeric structure for the complex sulfates is proposed, as in the case of the complex nickel(II) nitrate. However, in the case of the complex sulfates one of the bridging hydroxyl groups appears to have been deprotonated by the sulfate ion which then exists in the solid as the hydrogen sulfate ion. Treatment with base removes another proton from the complex with the result that the elements of sulfuric acid are eliminated from the complex.
The solid-state complex sulfates for which polymeric structures have been proposed produce visible spectra for the individual metals distinct from the spectra of other salts of the same metal and their aqueous solutions. However, the aqueous solution spectra of the complex sulfates are identical to spectra produced by aqueous solutions of the respective metal nitrates or chlorides, indicating that the polymeric structures exist only in the solid state.




58
Conductivity data (Figure 27) support the existence of dipositive, diaquo species (9, P. 339) in aqueous solutions of the sulfates and indicate that species of condensed structures are present in methanol solutions. The complexes present in methanol solutions exhibit visible spectra distinct from the spectra of the respective solid complex sulfates or their aqueous solutions. Hence another condensed complex sulfate structure exists in methanol solution. An indication that a new type of complex is formed in methanol solutions comes from the observation that the complex nickel and copper sulfates require several hours to dissolve in methanol to produce a 5xlO-3 m solution. The complex cobalt sulfate only partially dissolves in methanol, a color change having occurred in the insoluble portion.
Figure 28 shows a model of a possible solid-state complex sulfate structure. Only the dipositive, dimeric cation is shown. The anions not shown are hydrogen sulfate ions.
Deprotonated Complexes
The deprotonated complexes investigated have the following metalto-ligand ratios as determined by carbon and metal analysis: M:DPK, 3M:4DPK, and M:2DPK. In general, available physical methods short of X-ray crystal structure analysis provide insufficient information to establish with any degree of certainty the structures of these deprotonated complexes. An analogous system is that of simple metal ions in aqueous solution whose deprotonated species indeed exhibit quite complex behavior.




59
250-
0
0
2 I
c.J
2d
E
C
~200
C
0
0
50
0 i__.01' .02 .03 Cd 4 .05 .0.7
Figure 27.-The molar conductivities in methanol of:(a), Ni(DPKH 20)2
so041/2H 20; -(b), Cu(bPKH 20) 2so4 1/2H 20- and in water; (c),
Ni(DPKH 2O)2S4 1/2H12 0. (d), Cu(DPKH 20) 2so4 1/2H 0; (e),
Co (DPKYI2 0) 2 so0 H2 0.




60
Figure 28.- Two views of [Co(DPKH20)(DPKOH)] 2.




61
However, certain statements can be made about the structural natures of these compounds. Table 3 lists the specific complexes prepared and also includes infrared, equivalent weight, and molecular weight data. The anionic cpmponent of these complexes is either deprotonated water (0 and/or OH) or deprotonated di-2-pyridyl ketone hydrate (DPKOH- and/or DPKO 2-).
Infrared data suggest that deprotonated DFKH20 serves the
anion function in these complexes. The band near 1400 cm- referred to in Table 3 is assigned to the 0-H bending vibration of the alcohol
group (ll) and is present in most of the hydrated salt complexes dis-1
cussed earlier. The band near 1400 cm in the salt complexes is removed by deuteration and in certain cases by treatment with base.
Treatment of the salt complexes with base of course produces the
complexes listed in Table 3, and it can be seen in the infrared spectra shown in Figure 29 that none of the deprotonated complexes has a band
-l
at 1400 cm of the intensity shown by the spectrum of Co(DPKH20) SO4 H20. The spectrum of Cu3(DPKO)2(DPKOH)27H20 has a poorly defined band at
-1
1400 cm which is not found in the spectrum of CuDPKO7H20 (which should contain no alcohol hydrogen atoms).
The infrared spectrum of Cu3(DPKO)2(DPKOH)27H20 (Figure 29b) indicates that two chemical arrangements of deprotonated di-2-pyridyl ketone hydrate are present. Two bands are present near 1600 cm-1 in the region of the highest energy pyridine band,suggesting that two types of pyridine species are present. On the other hand, the spectrum of
CuPK7H 0 (Fi-lure 29a) shows only one band near 1600 cm as expected.
CuDPKO7H20 (Figure 29a) shows only one band near 1600 cm as expected.




Table 3
Deprotonated Complexes Observed Calculated Molecular
Formula Equivalent Equivalent Weight
Compound IR Spectra Weight Weight Weight
I Co(DPKOH) 2 1/2H20 Like Co(DPK)2S043H20 470 234 235 378
No band at 1400 cm 11 Co(DPK)25 1/2H20-3H+ All bands broad -1 524 515 175 358
No band at 1400 cm III Cu(DPKO)2(DPKOH)27H 0 Band at 1400 cm-1 re- 1120 185 187 502
moved by deuteration IV CuDPKO7H20 Fewer bands than III 390 194 195 --*
No band at 1400 cm-1 V PdDPKO2H20 Similar to IV 327 -- --*
Insoluble in methanol. Insoluble in hydrochloric acid.
ON




63
e eU
C
z ~
I A FREQUENCY (cm'.] Figure 29.-The infrared spectra of:(a), CuDPK07H 20; (b), Cu 3(DPKO)2
(DPKOH) 27H 20; (c), Co(DPK) 25 1/2H 20-3H +; (d) Co(DPKOH) 2
1/2H 20; e), Co(DPKH 20) 2SO LjH 20.




64
A possible structure for Cu 3(DPKO) 2(DPKOH) 27H 20 having two distinct types of ligands is shown in Figure 30c. An analogous structure for CuDPKO7H 20 is shown in Figure 30a. A similar structure lacking the two trans water molecules might be expected for PdDPKO2H 20. However, a structure of the type shown in Figure 30b is also possible, although the infrared spectrum of PdDPKO2H 20 is not that of the simple hydrated ketone.
The equivalent weights of both copper compounds are seen in
Table 3 to match closely the calculated values. However, similar agreement between formula weight and molecular weight in methanol is not observed for Cu 3(DPKO) 2(DPKOH) 27H 20, perhaps because solution in methanol results in dissociation into neutral fragments in addition to an acid-base reaction producing methoxide ions. Conductivity data (Figure 31) support the existence of ionic species in methanol.
It was pointed out in an earlier discussion that the deprotonated compound Co(DPKOH) 1/2H 20 has an infrared spectrum quite similar to that of Co(DPKH20)2So4H20; both spectra are distinct from the spectra of other neutral and salt complexes. A polymeric structure involving bridging hydroxyl groups is probable for Co(DPKOH) 21/2H 20. But as in the case of the copper compound, the value for its molecular weight in methanol (378) is less than the formula weight (470), indicating that not polymerization but dissociation occurs in methanol.
Conductivity data indicate that methanol solutions of Co(DPKOH) I/2H2 0 are electrolytic conductors (Figure 31), as noted for solutions of the copper compound'Cu (DPKO) 2(DPKOH) 27H2 0. Methanol may react,
3 2"22




H H C
22 2
H H
H ~ Pd itPd~
-0H
22
n
a
Figure 30.-Possible structures for:(a), CuDPK07H 20; (b), PtDPK02H 20; (c), Cu 3(DPKO)2 (DPKOH) 7H 0. &r
2 2\-




6 6
150
E
0
E
U%
E
U
0
0
00 50 C.) a
.0 0 0 lT0 0 0 0
Fiue3 -h oa odciiis nmtao f a oDK /
Figre31-The molar codtiiie 2n mtHao of:(a(), CO)2(DPKO) 52
7H 20.




67
donating a proton to the basic complex to form methoxide ions and complex cations. Moreover, dissociation of the unreacted polymeric species into neutral fragments probably occurs in methanol.
The complex, Co(DPK) 25 l/2H 20-3H+ is formulated as a Co(Ill) compound because of its unusually low magnetic moment (0.96BM) and high apparent equivalent weight (515 vs. 175 calculated). The great majority of Co(Ill) compounds are low spin and diamagnetic, hence a low magnetic moment would be expected. The chemical inertness of Co(III) ions quite likely would prevent protonation of one or more anionic oxygen atoms. Only one anionic oxygen atom of the three required to balance the three positive charges of Co(III) in Co(DPK) 25 l/2H 20-3H+ appears to accept a proton since the observed equivalent weight is equal t o the formula weight.




SUMMARY
It is possible to formulate from the earlier discussion a pattern of behavior for di-2-pyridyl ketone (DPK) as a ligand in aqueous solution based on the following factors: [I] the tendency for hydration of the ketone carbonyl to occur, [2] the steric problem in Pt(II) and Pd(ll) compounds containing two ligand molecules, [3] the tendency to form complexes with Cu(II), Co(II), and Ni(II) in which the number of DPK ligands is two or less, and [4] the acidic nature of the bis(di-2-pyridylketonehydrate)metal(II) cations.
All complexes prepared in aqueous solution contained at least one molecule of the hydrated ketone except [Pt(Pd)DPKCI 2]. The hydration of the ketone carbonyl appears to be enhanced by coordination to the extent that dehydration of many of the solid hydrates occurred only near or above 1000C. Further, hydration of all ketone molecules
present occurs unless prevented by steric interactions (as in the case of [CoDPK(DPKH20)CI2]H20 and [Ni(DPK)2(NCS)2]2H20). The related reaction of ketal formation occurs in methanol, producing a ligand of almost the same nature as the original ketone hydrate.
An important facet of the coordination chemistry of di-2-pyridyl ketone is the steric interaction which occurs in complexes containing two molecules of the anhydrous ketone bound in a rigidly planar fashion. Evidence for this interaction was found in the thermal instability of
68




69
[Pt(Pd)(DPK)2]Cl2 relative to [Cu(Co)(DPK)2]CI 2. The consequences of this steric interaction are, in the case of first row transition metals, that only cis structures are expected for the octahedral complexes of the type [M(DPK)2ClI2]. A similar interaction was not indicated in trans-bis(di-2-pyridylketonehydrate)metal(II) cations because a nonplanar boat arrangement of the hydrated ligands is possible.
Most complexes of Ni(II) and bidentate di-imines disproportionate in aqueous solution to form one trisdi-imine cation and one hexaaquo cation. It is therefore unusual that complexes of Ni(II), Cu(II), and Co(II) containing only two molecules of di-2-pyridyl ketone hydrate are isolated from aqueous solution. Inspection of molecular models of the tris(di-2-pyridylketonehydrate)metal(II) complexes shows that there is considerable steric interaction which is perhaps the reason why no tris complexes were isolated. Moreover, hydrogen bonding between the C-OH oxygen atoms and the trans water hydrogen atoms may occur in the diaquobis(di-2-pyridylketone)metal(II) complexes to provide additional stabilization.
Finally, the acidic nature of bis(di-2-pyridylketonehydrate) metal(II) complexes terminates the characterization of di-2-pyridyl ketone as a ligand. All complexes investigated exhibited acidic behavior as shown by abnormal conductivity behavior and the isolation of deprotonated complexes. Cu(II) formed complexes with metal-to-ligand ratios of 3:4 and 1:1. Palladium formed a 1:1 complex much like the Cu(II) analog. Cobalt yielded two complexes with ratios of 2:1, one of which appeared to contain Co(Ill). No complexes with either discrete or reproducible metal-to-ligand ratios were isolated for Ni(II).




A P P E N D I C E S




Appendix A
VISIBLE SPECTRA
A common spectrum having a maximum near 5600A0 is observed
for aqueous solutions of all the copper salts investigated. In addition, the solid complexes, [Cu(DPKH20)2(H20)2]CI22H20 and [Cu(DPKH20)2(H20)2 NO3)2,exhibit one band near 5600A in the solid state. Such a spectrum for Cu(II) compounds is consistent with a tetragonal structure as evidenced by the spectrum of [Cu(en)2(H20)21 + (en=ethylenediamine) (Figure 32a), a known tetragonal complex cation.
The anhydrous copper complexes, [Cu(DPK)2ClI2] and [Cu(DPK)2
(NO3)2] were assigned cis structures on the basis of visible and infrared spectral evidence. The 2,2'-dipyridine analog [Ni(Dipy)2Cl2] has been assigned an octahedral structure (12) and the complex cations
2+ ]2+
[Cu(Dipy)2(H20)2 2+ and [Cu(Phen) (H20)2 2+ (Phen=1,10-phenanthroline) have been assigned cis structures in aqueous solution (13).
Evidence for the existence of a trans diaquonickel(II) cation
in aqueous and methanol solutions is provided by the fact that the Ni(II) solution spectra of di-2-pyridyl ketone hydrate complexes (Figure 21b) match.closely the solution spectra of the complex Ni(Salicylaldehyde)2 (Figure 32b) known by X-ray crystal structure analysis to be trans in the solid dihydrate(II) (14).
In regular octahedral complexes three absorption bands are
expected corresponding to the transitions indicated on the energy level
71




72
I Dimethyt lotrnvmde x UtE Powder
DZ Pyridine I '*'
400 600 100 20 40 .(A)
F1a
002
00
mote of curcchloride a md 0.005, 0.01 nd002 mote -of
ethyeneir av e leg mz
Figure 32.-Reproductions of the visible spectra of:(a), Aqueous
solutions containing cupric chloride and ethylenediamine
(15); (b), Ni(salicylaldehyde) 2 (16).




73
diagram shown in Figure 33. The lowest energy transition (d) corresponds to the crystal field splitting parameter, Aand the transition next highest in energy (c) corresponds to 1.8A, while the highest energy transition (a) is a function of the energy difference between the energy states, 3F and 3. of the free ion as well as a function of A .
The spectra of [Ni(DPK) 2(NO 3) 21, Ni(DPK) 2NO 32H 20, and Ni(DPK)2 (NO3)22H20 shown in Figure 21 contain more bands than the spectra of the chloride complexes (Figure 17) and more bands than aqueous solutions of Ni(II) ions. Figure 33 shows an energy level diagram for Ni(II). The three transitions normally observed for octahedral Ni(II) are indicated; however, a fourth band (b) is sometimes observed and is designated 3A2 ) I E. Perhaps the additional bands in Figure 21 are produced by this transition, i.e., 3A E.
Table 4 lists spectral assignments for some of the nickel compounds investigated.




74
ds B 1080 cm-1 for Ni(11) 80 T ~ F
70r(ei
60 4I
IS-e
40-
30
20- IE
I
10 -Oaj 0 20 AB30 40 50
d
*a= 3A22-'T1 b= 2A E
* 3A 2 T d= 3A2 T2
*Transitions normally observed f or octahedral Ni(II).
Figure 33.-The energy level diagram for Ni(II) in an octahedral
field.




Table 4
Spectral Assignments for Some Ni(ll) Compounds in the Solid State Transition (cm-1)
2 TE3 A T(3p)
Complex 3A24- 3T2 3A2- 3TI 3A2 E 3A2.- 3T 13
[Ni(DPK)2CI2] 9000 18200 -- 24700 9000
[Ni(DPK)2(NCS)]2H20 10900 18500 -- 23500 10900
[NiDPK(DPKH20)CI2J2H20 9090 17500 -- 22700 9390
[Ni(DPK)2(N03)2] 10000 18200 12900* 23600 10000
Ni(DPK)2(N03)23H20 10500 19300 13200* -- 10500
Ni(DPK)2(NO3)22H20 10200 15900 12800 23800 10200
+The spectra are shown in Figures 17 and 21. Average value of more than one band.




Appendix B
MAGNETIC MOMENTS
The magnetic moments ,for most of the compounds investigated are listed in Table 5.
All are within the normal octahedral range for the individual metals (Cu(II), 1.70-2.20BM; Ni(II), 2.80-3.50BM; and Co(Il), 4.305.20BM, except the value for Co(DPKH20)2SO H20 and the value for Co(DPK)25 1/2H20-3H Data for Co(DPKH20)2SO4 H20 are shown in Figures 34 and 35 and Table 6. Such behavior has been observed before and a quantitative interpretation has been attempted (17).
A similar effect has been observed for a strongly tetragonally
distorted Cobalt(II) complex (18),which perhaps indicates that Co(DPKH20)2 S04H20 is similarly distorted.
The magnetic moment observed for Co(DPK)25 1/2H20-3H (0.96BM) is far too low for Co(II), hence the compound is assumed to contain Co(IIl) which in most compounds is low spin and therefore diamagnetic. The residual paramagnetism observed for the above compound is not well understood and requires a thorough investigation.
76




77
Table 5
Room Temperature Magnetic Moments
Complex ~qeff
Cu(DPK) 2 C I26H2o0 1.90
Cu(DPK) (NO ) 4Hi 0 1.83
2 3 2 2
Ni(DPK) 2(NO 3) 23H 20 3.12
Ni(DPK) 2Cl 23H 20 3.10
Ni(DPK) 2Cl 23.16 Co(DPK) 2Cl 23H 20 4.74
Co(DPK) 2(SCN) 2H 20 4.97
Ni(DPK) 2(ScN) 2H 20 3.08
Cu(DPK) 2S04 2 1/2H 20 1.98
Co(DPK) 2SO 43H2 0
Ni(DPK) 2 so42 1/2H 20 3.14
Co(DPKOH) 21/2H 20 4.45
Co(DPK) 25 1/2H 20-3H + 0.96
CU 3 (DPKO) 2(DPKOH )27H 20 1.80
CuDPK07HO 1.99
"See Table 6 and Figures 34 and 35.




350
- 300
250
200[
., I t T t t
100 160 220 280 340 400
T (KO) Figure 34.-The temperature susceptibility of Co(DPK)2SO 43H20.




4.0
3.5
4-.
C
0
U
3.0
2.5
oo
2.0 I
150 200 250T (K 300 350 400
Figure 35.-The temperature dependence of the magnetic moment of Co(DPK)2SO43H20.




80
Table 6
Temperature Dependence of the Molar Susceptibility
and Magnetic Moment of Co(DPK)2SO43H20
T, K x 106(cgs units) Aeff(Bohr magnetons)
124.99 4806 2.20
139.35 4529 2.24
152.98 3945 2.20
294.65 3188 2.74
310.15 3294 2.86
328.59 3759 3.14
346.17 4378 3.48
365.55 5044 3.85
382.99 5398 4.07
398.92 5494 4.20
174.51 3444 2.19
192.45 3191 2.22
210.31 2972 2.24
230.00 2831 2.28
250.00 2768 2.35
260.00 2768 2.40
270.00 2766 2.45
280.00 2828 2.52
294.65 3002 2.66




Appendix C
INFRARED SPECTRA
The infrared spectra, of [PtDPKCl2] and di-2-pyridyl ketone are shown in Figures 36 and 37. The greater number of bands in the spectrum of di-2-pyridyl ketone (Figure 36) suggests that both cis and trans conformations exist in the molten free ligand whereas, as expected, only a cis conformation is present in [PtDPKCI2] (Figure 37). 2,2dipyridine, a related molecule, does have a cis conformation in the solid state (19).
Figure 38 shows the infrared spectra of CuDPACI2, Cu(DPA)2C12, [PtDPACI2], and [Pt(DPA)2]CI22H20 (DPA=di-2-pyridyl amine). Splitting of the band corresponding to the iT -hydrogen out-of-plane bending vibrational mode occurs in both complexes containing two ligand molecules but does not occur in the complexes containing only one ligand molecule. This splitting is perhaps a spectral manifestation of the ligand distortion discussed earlier in connection with the problem of interligand steric interaction. If this is the case, the structure of the copper complex, Cu(DPA)2Cl2,would be expected, like the platinum analog, to involve a planar arrangement of the donor nitrogen atoms and a nonplanar boat arrangement of the two ligand molecules.
81




LI
1700 '500 1300 1100 !900 700
FREQUENCY (cm1)
Figure 36.-The infrared spectrum of di-2-pyridyl ketone (Imelt on NaCI mull plates). 0




z
17010 10 10 o 0
FRQUNC (c11
Fiur /7-h nrrdsetu PDK1 Krds)
IC




84.
aA A
dp }
b ~ ~~ AIAr 1
4000 3000 2000 1000
FREQUENCY (cm )
Figure 38.-The infrared spectra of:(a),[PtDPAC12] (b),
(Pt(DPA) 2]C122H2o; (c), Cu(DPA) 2 C12; (d),
CuDPACI 2




85
Deuteration of the complex, [Pt(DPKH20)2]CI24H20,produces considerabe change in its infrared spectrum as is seen in Figures 39 and 40.
No clear explanation,is readily apparent for the several shifts
-l -l
observed in the region 2000-625 cm. In the region 4000-2000 cmmore normal behavior is observed with one peak being shifted to the 1/
predicted value (Y hydrogen=2w2'deuterium).
The possibility of exchange of ring hydrogen atoms for deuterium atoms was ruled out by decomposing the deuterated complex into [PtDPKCl 2 and DPK, whose infrared spectra revealed no abnormalities.




0
Sf I
F
1700 1500 1300 1100 900 700
FREQUENCY (cm-1)
Figure 39.-The infrared spectrum of [Pt(DPKH20)2]CI24H20 (KBr disc).
0
or




1700 1500 1300 1100 900 700
FREQUENCY (cm1)
Figure 40.-The Infrared spectrum of [Pt(DPKH20)2]Cl24H20 recrystallized from D20 (KBr disc).
22 2202




88
Selected Infrared Spectra
Representative infrared spectra of each type of salt complex and each type of deprotonated compound investigated are shown in the following pages. All spectra were obtained using KBr discs. The ordinate of each curve is in units of transmittance (%), and the abscissa is in units of frequency (cm-l




3800 3400 3000 2600 2200 1800
Figure L1.4[Cu(DPKH 2O) 2(H 20) 2ICI2 2H 20.
2 22




1 1 I 1 1
1700 1500 1300 1100 900 700
Figure 42.-[Cu(DPKH 0) (H 0) 2]CI 2H 0.
2 222 22




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AN INVESTIGATION OF SOME SIX-MEMBERED CHELATE RING SYSTEMS By FOY WYMAN MORGAN A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF THE UNIVERSITY OF FLORIDA IN P A.RTIAL FULFILLMENT OF THE REQUIREMENTS FOR TI-1.E DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA Augu s t, 1967

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ACKNOWLEDGMENTS The author wishes to express his sincere appreciation to Dr. R. C. Stoufer for his valuable direction and personal friendship during the past four years. wish also to thank the remaining members of my committee, Ors. R. D. Dresdner, E. H. Hadlock, W. M. Jones, ~nd J. D. Winefordncr, for their ~ssist~ncc. In addition I would 1 ike to thank Mr. J. G. Norman for his loyal support and cilso to th a nk the following members of the Depart ment of Chemistry for their understanding help: Mrs. Em.11a Bm '1ffia n, Mr. Forest A. Cheves, Miss Mary H e len Hall, Mrs. Evelyn Lea, Mr. Wil 1 iam E. Luckhurst, Mr. Joseph W. Miller, Sr., Mr. Morris D. Mixson, and Mr. Trueman Robbins, Jr. My grateful appreciation is extended to Mrs. Jack Smith for the expert typing of this dissertation and for the personal inter est taken by her although she was already heavily com11itted to other endeavors. I am grateful to my wife for her continuing invaluable assistance which nas spanned the past eight years and which in the particular case of this dissertation involved typing the rough draft, preparing numerous figures, and providing considerable editorial assistance. ii

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ACKNOWLEDGMENTS LIST OF TABLES. LIST OF FIGURES INTRODUCTION ..... EXPERIMENTAL PROCEDURES Apparatus ..... RESULTS AND DISCUSSION. TABLE OF CONTENTS Complex Salts of Cu(( I). Complex Salts of Co(II) and Ni(II) Deprotonated Complexes SUMMARY .... APPENDICES ...... A. VISIBLE SPECTRA. B. MAGNETIC MOMENTS C. INFRARED SPECTRA Selected Infrared Spectra BIBLIOGRAPHY .... BIOGRAPH I CAL SKETCH iii Page ii iv V 3 l l 13 23 38 58 68 70 71 76 81 88 112 113

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Tf\ n1 lMUL.L 1. LIST OF TABLES X-Ray Diffraction D ata : 28 Valu es and Relative Inten s ities ........ 2. X-Ray Diffraction D ata: 28 Valu e s and Relative Int en sities 3. Deprotonated Co~plexes 4. Sp ectra l Assignm ents for Som e Ni(I I) Compounds+ in the Sol id State .... 5. Room Temperature Magnetic Moments. 6. Te mperatu r e Dep endence of the Molar Susce ptibi lity Page 53 54 62 75 77 and Magn e tic Moment of Co(DPK) 2 S\3H 2 0 . . 80 iv

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LIST OF FIGURES n ............ r O'::JC 1. The infrared spectra of: (a) ,[PtDPK(DPKH'")O)]Cl ; ,. 2 (b) ,[Pt(DPKH 2 0) 2 ]C1/fH 2 0; (c) ,[PtDPKC1 2 ]; (d) ,DPK. 15 2. Th e TGA curves for: ( a ) ,[Pt(DPKH 2 0) ]Cl LrH O; 2 2 2 (b) ,[Pt(D PA ) ]Cl 2H 0 ........... 2 2 2 16 3. Th e TGA curves for: (a) ,[Cu(DPKH 2 0) (H 0) ]Cl 2H O; 2 2 2 2 2 (b) ,[CoDP K (DP KH O)C1 2 ]2H O 2 2 18 4. The natur e of the proposed steric interaction across the coordinate plane of [Pt(D PK ) 2 ]c1 2 20 5. Prentice-H a l] models of: (a), Th e 11 boat 11 configuration form ed by di-2-pyridyl ketone hydrate in 2+ 2+ complex es; (b) ,[Pt(DPKH 0) ] ; (c) ,[PtDPK(DPKH 0)] 21 2 2 2 6. Th e infr are d spectra of: (a) ,[Pt(DP KH 0) ]Cl 4H O; 2 2 2 2 (b) ,[Cu(DPKH 2 0) (H 0) ] Cl 2H O; (c) ,[Cu(DPK) Cl J 222 22 22 24 7. The positions of the absorption maxima of: (a), [Cu(DPKH 2 0) (H 0) ]Cl 2H O; (b),[Cu(DPKH 2 0) (H 0)] 2 2 2 2 2 2 2 2 (NO ) 2 ; (c), Cu(DPKH 0) so 4 1/2H 0. . . 26 3 2 2 2 8. 9. The molar conductivities in water of: (a) ,[Pd(DPKH 0) ] 2 2 C1 2 LfH O; (b) ,[Cu(DPKH 2 0) (H 2 0) ] (NO) ; (c), 2 2 2 3 2 [Cu(DP KH 0) (H 0) ]cl 2 2H O ........ 2 2 2 2 2 The solution spectra (H 0) of [Cu(DPKH O)(H 0) J 2 2 2 2 -4 -4 Cl 2 2H 2 0: (a), 3.8 x 10 m; (6), 3.8xl0 m .,, ith 3 -L f drops 30 % perchloric acid in 30 ml; (c), 3.8 x 10 m with 10 drops perchloric acid in 30 m l V 28 29

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FiGURE 1 o. LIST OF FIGURES, Continued The solution spectra of: (a) ,[Cu(DPKH 0) (H 0) ] 2 2 2 2 Cl 2H O in \"later (2. cm cells) 3.Bxl03 m; (b), 2 2 [Cu(DPKH 2 0) (H 2 0) ](NO ) in methanol (2 cm eel ls) 2 2 3 2 3.0xl03 m (c) ,[Cu(DPKH 2 0) (H 0) ]Cl 2H O in 2 2 2 2 2 methanol (2 cm eel ls) 3.6 x l03 m .. 11. The molar conductivities in methanol of:(a), 12. 13. 14. [Cu(DPK) Cl ]; (6) ,[Cu(DPKH 0) (H 2 0) ]Cl 2H 2 0; 2 2 2 2 2 2 (c) ,Cu(OPKH 2 0) (H 0) (NO) 2 2 2 3 2 The infrared spectra of: (a) ,Cu(DPK) 2 (NO ) ; 3 2 (6) ,Cu (DPK) (Cl) 2 2 . . The infra red spectra of:(a),Cu(DPKL(NO); L 3 2 (6) ,Cu(DP K ) (Cl) 2 2 . The sol id-state absorption spectra of: (a), . [Cu(DPK) Cl 2 ] (diffuse reflectance); (b) ,[Cu(DPK) 2 2 (N0 3 )] (Nujol mull); (c),[Cu(DPKH 0) (H 0) ]Cl 2H 0 2 2222 22 (diffuse reflectanc e ) .......... 15. The infrared spectra of:(a),[Cu(DPKH 0) (H 0) J 2 2 2 2 Cli2H 2 0; (6) ,[NiDPK(DPKH 2 0)Cl 2 ]2H 2 0; (c) ,[CoDPK (DPKHO)Cl ]2HO; (d),[Ni(DPK) Cl l. 2 2 2 2 2 16. Prentice-Hall models of: (a), !~an~-[NiDPK(DPKH 2 0) H 2 0cl]; .,_,ith one hydrogen bond shown; (6), cisvi Pag e 31 32 34 35 37 39 41

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LIST OF FIGURES, Co~lnu~~ F!GUP.E 17. Diffuse reflectance spectra of: (a) ,[Ni (DPK\c1 2 ]; (b) ,[NiDPK(DPKH O)Cl ]2H O; and solution spectra of: 2 '2 2 [NiDPK(DPKH O)C1 2 ]2H 0, 5xl03 m 10 cm cel 1: (c), 2 2 water, (d), methanol .. 18. The m8lar conductivities in methanol of: (a) ,[CoDPK 19. 20. 21. (DPKH O)C1 2 ]2H O; (b) ,[NiDPK(DPKH O)Cl ]2H O; (c), 2 2 2 2 2 Ni (DPK) (NO ) 3H O; and in water of: (d) ,Ni (DPK) 2 (NO ) 2 2 3 2 2 3 3H 0; (e) ,[NiDPK(DPKH O)Cl ]2H O; (f) ,[CoDPK(DPKH 0) 2 2 2 2 2 The infrared spectra of: (a) ,[Cu(DPKH 0) (H 2 0) J 2 2 2 C1 2 2H O; (b) ,[Ni (DPK) (NO ) ]; (c) ,Ni (DPK) (NO ) 2 2 3 2 2 3 2 2HO; (d), Ni(DPKHO) (N0 3 ) HO ... 2 2 2 2 2 The TGA curve for: Ni(DPKH 0) 2 (NO) H 0 2 3 2 2 Nujol mul 1 spectra of: (a) ,Ni (DPK) (NO ) ; (c), 2 3 2 Ni(DPK) 2 (N0 3 ) 2H O; (d), Ni(DPK) (NO) 3H O; and 2 2 2 3 2 2 the solution spectrum (H 0, 5.lxlo3 m 10 cm cell) of: 2 (b), Ni(DPKH 2 o) 2 (N0 3 ) 2 H 2 0 ..... 22. The 'infrared spectra of: (a) ,[Ni(DPK) (NO) ]; 2 3 2 23. (b),[Ni(DPK) Cl ] .. 2 2 The infrared spectra of: (a) ,Ni (DPK) (NO ) 2H O; 2 3 2 2 (b), Ni (DPKH 0) (NO ) HO; (c) ,[Cu(DPKH 2 0)'2(H 0) j 2 2 3 2 2 2 2 C 1 2H 0. 2 2 vii 42 43 45 46 47 50

PAGE 8

FIGURE 24. 25. The infrared spectra of: (a) ,[Ni (DPK) Cl ]; 2 2 (b),[Ni(DPK) (NCS) ]2H O; (c),[Co(DPK) (NCS) ]H 0. 2 2 2 2 2 2 The infrared spectra of: (a), Co(DPKH 0) s 4 H r 0; 2 2 "L (b), Ni(DPKH 2 o) 2 so 4 1/2H 2 0; (c), Cu(DPKH 2 2 s 4 1/2H 2 0; (d) ,[Cu(DPKH 0) (H 0) ]Cl 2H O 2 2 2 2 2 2 26. The TGA curves for: (a), Cu(DPKH 2 o) 2 S0 1 fl/2H 2 0; (b), Co(DPKH 2 o) 2 SOL~H 2 0; (c), Ni (DPKH 2 o) 2 so 4 1/2H 2 0 27. The molar conductivities in methanol of: (a), 28. 29. Ni (DPKH 2 o) SO, l/2H O; (b), Cu(DPKH 0) so 4 1/2H O; 2 q 2 2 2 2 and in "'-'ater; (c) ,Ni (DPKH 0) SO l/2H O; (d), 2 2 4 2 Cu(DPKH 0) S0 1 l/2H O; (e) ,Co(DPKH 0) SOL H 0. 2 2 4 2 2 2 f2 Two views of [Co(DPKH 0) (DPKOH)] 2 + 2 2 The infrared spectra of: (a), CuDPK07H O; (b), 2 + Cu 3 (DPK0) 2 (DPKOH) 2 7H 2 0; (c), Co(DPK) 2 5 l/2H 2 0-3H ; (d), Co(DPKOH) l/2H O; (e) ,Co(DPKH 0) S0 4 H 0 2 2 2 2 2 30. Possible structures for: (a) ,CuDPK07H 2 0; (b), PtDPKO 2H O; (c), Cu (DPKO) (DPKOH) 7H 0. 2 3 2 2 2 31. The molar conductivities in methanol of:(~), + Co(OPK) 2 5 l/2H 2 0-3H (b), Co(DPKOH) 2 l/2H 2 0; (c), Cu(OPK0) 2 (DPKOH) 7H 0. 2 2 32. Reproductions of the visible spectra of: (a), Aqueous solutions containing cupric chloride and Page 51 55 56 59 60 63 65 66 ethylenediamine (15); (b), Ni (sal icylaldehyde) 2 (16) 72 viii

PAGE 9

LIST OF FIGURES, Continu ed FIGURE Page 33. The energy level diagram for Ni(II) in an octahedral field 34. The temperature susceptibility of Co(DPK) so 4 3H 0. 2 2 35. The temperature dependence of the magnetic moment of Co(DPK) S0 4 3H O ... 2 2 36. The infrared spectrum of di-2-pyridyl ketone (melt 37. 38. 39. 40. l+ 1. 42 _44. 45. 46. 47. 48. 49. 50. on NaCl mull plates) .. The i~frared spectrum (PtDPKC1 2 ] (KBr disc). The infrared spectra of: (a) ,[PtDPACl ]; (b), 2 [Pt(DPA) ]Cl 2H O; (c), Cu(DPA) C1 2 ; (d), CuDPACl 2 2 2 2 2 The infrared spectrum of [Pt(DPKH 0) ]Cl 4H O (KBr disc) 2 2 2 2 The infrared spectrum of [Pt(DPKH 0) ]Cl 4H 0 2 2 2 2 recrystallized from o 2 o {KBr disc) [Cu{DPKH 0) 2 (H 2 0) ]Cl 2H 0 2 2 2 2 [Cu(DPKH 2 o) (H 0) ]Cl 2H 0 2 2 2 2 2 [NiDPK(DPKH O)Cl ]2H 0 2 2 2 [NiDPK(DP K H O)Cl ]2H 2 0 2 2 [Ni ( DPK) C 1 ]. 2 2 [Ni (DPK) 2 c1 2 J. Ni(DPKH 0) (N0 3 ) 2 H 0 2 2 2 Ni(DPKH 0) (NO) H 0 2 2 3 2 2 [Ni (DPK) (NO ) ] 2 3 2 [Ni (DPK) 2 {No 3 ) 2 Jix 74 78 79 82 83 86 87 89 90 91 92 93 94 95 96 97 98

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LIST OF FIGURES, Continu e d FiGURE Page 51. Ni (DPK) (NO) 2H 0 2 3 2 2 99 52. Co(DPKH 0) SO H 0. 2 2 4 2 100 53. Co(DPKH 0) SO H 0. 2 2 4 2 101 54. [Ni(DPK) (NCS) ]2H 0 2 2 2 102 55. [Ni (DPK) (NCS) ]2H O 2 2 2 103 56. Cu 3 (DPKOH) 2 (DPK0) 2 7H 2 0 104 57. Cu 3 (DPKOH) (DPKO) 7H 0 2 2 2 105 58. Co(DPKOH) 2 1/2H 2 0 106 59. Co(DPKOH) 2 1/2H 2 0 107 60. CuDPK07H 0 108 2 61. CuDPK07H 2 0 109 62. Co(DPK) 5 l/2H 0-3H+ 110 2 2 63. Co(DPK) 2 5 1/2H 0-3H + 111 2 X

PAGE 11

INTRODUCTION Ligands of the type illustrated @it) in Stru ct ure I have received little attention except for di-2-pyridyl amine (X = N, R = H), which exhibits behavior typical of bidentate 1 ig an ds with coordinate bond formati on restricted to the two pyridine nitro gens (1). The acidity of the amine hydrogen h as been d emon strat ed (2) and the involve men t of the deprotonated nitrogen in coordinate bond formation pr opose d (3). Comple xes have b ee n report e d which contain from one to three molecules of di-2-pyridyl amin e and struc tural assignm e nts made which embrace the common types, i.e., t et ra hedral, planar, and octahedral (1-4). Ligands in which the bridging atom is a carbon atom (X = C) have not receiv e d the attention directed toward di-2-pyridyl amin e perhaps because considerable synthetic difficulties arise since forrna ti on of the carbon-carb on bond requires use of the uns tab 1 e cl.. pyridyl Grignard reagent (or~ -1 ithiopyridin e ). Howev e r, di-2pyridyl ketone has re cent ly become com:n e rcially available. Di-2-pyridyl ketone (or di-2-pyridyl amine) is formally similar to other bidentate I igands such as acetyl acetone, salicylic acid, 1,8-diaminonaphth a lene, imines formed by sal icylaldeh yde etc., in that al 1 form six-membered chelate ring systems. However, the resem blance to di-2-pyridyl ketone is close s t in th e case of ac e tyl acetone.

PAGE 12

Both I igands have TT'electron systems and both are of the same symmetry, c 2 v (~~e C-0 bond lengths of acetyi acetone H 3 C0,yCH 3 QMO are equivalent in complexes, ) But of greater importance is the fact that both possess, as do few other I igands of any type, sites susceptible to chemical attack under mild conditions. In the case of complPxPS of a~ptyl a~etnn P, thP lone ring hydrog e n undergoes substitution in a whole series of reactions typical of aromatic systems (halogenation, nitration, suifonation, chloromethylation, etc.) (5). The reactive site in di-2-pyridyl ketone is, of course, the carbonyl group which, in the uncoordinated m o lecule, might be expect e d to undergo normal carbonyl reactions (reduction; formation of imines, hydrazones, and ketals; reactions with hydr oge n cyanide, Grignard reagents; etc.). Hydration of the ketone carbonyl, a less co mmo n reaction, occurs only to a slight extent and only in aqueous solution (e x cept for p dike~ones, fluroketones, etc.) with the resulting absence of stable hydrates. The specific property of hydration and the influence of coordination upon th e hydration of di-2-pyridyl ketone, togeth e r with the physicaJ and ch em ical nature of the resulting hydrates, constitutes in large part the work d e scribed h ere in. Co mp le xes of thr ee first row transition metal ions [Co(II), Ni(II), and Cu(II)] w e re isolated and characterized as sulfates, nitrates, chlorides, and thiocyanates. To a lesser degree, the chloride and tartrate salts of the comple xe s of Pt(I I) and Pd(II) were investigated. 2

PAGE 13

EXPERiMENTAL PROCEDURES Di-2-pyridyl ketone, DPK. The di-2-pyridyl ketone was obtained from Aldrich Chemical Company and used with no further purification. Di-2-pyridyl amine, DPA. The di-2-pyridyl amine was purchased from Reilley Tar and Ch e mical Company anrl wris st1hlim P. c:l h':'fOrl:' 1 1se_ Dichlorodi-2-e_yridylamineplatinum(l_!_l, [PtDPAC1 2 ]. A solution of potassium tetrachloroplatinate(II) (1.0 g, 0.0025 mole) in the minimum amount of water was added to a solution of di-2-pyridyl amine (0.86 g, 0.005 mole) in 25 ml of acetone. The resulting solution was heated on a steam bath, during which time the volume was maintained by adding acetone, until the initial red color had vanished. The yellow precipitate which formed was washed with acetone and diethyl ether and air dried. Anal. Calcd. for Ptc 10 H 9 N 3 c1 2 : C, 27.47; H, 2.08; N, 9.61. Found: C, 27.30; H, 2.28; N, 9.0Lf. Yield 0.89 g. Dichlorodi-2-pyriftyJ.ketonee.latinum(II), [PtDPKC1 2 ]. The di-2pyridyl ketone complex was prepared by the same method as the di-2pyridyl ami~e analog, [PtDPAC1 2 ]. Anal. Calcd. for Ptc 11 H 8 N 2 0c1 2 : C, 29.35; H, 1.79; N, 6.22. Found: C, 29.26; H, 1.71; N, 6.33. Dichlorodi-2-py~ketonepalladium(II), [PdDPKC1 2 J. A solution of di-2-pyridyl ketone (0.92 g, 0.005 mole) in N,N-dimethyl formamide (20 ml) was added to a solution of palladium(! I) chloride (0.89 g, 3

PAGE 14

0.005 mole) in warm N,N-dimethyl formamide (75 ml). The solution was allowed to co o l and was then filtered. The yellow sol id obtained was washed with acetone and diethyl ether and dried und er vacuu m Anal. Calcd. for PdC 11 H 8 N 2 0cl 2 : C, 3 6 .55; H, 2.23; N, 7.75. Found: C, 36.57; H, 2.22; N, 7.72. Yield approximately 1 .3 g. Bis(di-2-pyridylk etonehydra te)platinu m( II) chloride monohydrate [Pt(DPKH 2 o) 2 Jcl 2 H 2 0. A solution of di-2-pyridyl ketone (0.96 g, 0.005 mole) and potassium tetrachloroplatinate(II) (1.04 g, 0.0025 mole) in water (100 ml) was r ef luxed for eight hours. The re main ing yellow sol id was filt ered out and discard ed The filtrate was evaporated until crystal I i zat ion began and subsequently allo w ed to stand until cool. The white crystal] ine product was filtered out, washed with acetone and diethyl ether, and dried J..'2 va~uo at ro om te mpe r atu re. A small portion of the final product was recrystalli zed from water Anal. Calcd. for Ptc 22 H 22 N 4 o 5 c1 2 : C, 38.38; H, 3.22; N, 8.14. Found: C, 38.39; H, 3.29; N, 7.80. Yield 0.38 g. Bis (di -2-p_y.!:_l_d y 1 ke t onehy d rate) pa 11 ad i um il!_)__h l o r i de monoh_y~.I_.l te, [Pd(DPKH 2 o) 2 ]cl 2 H 2 0. This yellow mate rial was prep a r ed in a manner similar to that us ed to prepare [Pt(DP KH 0) ]Cl HO except that 2 2 2 2 palladium(!~) chloride was used and no unreacted material remained after one hour of refluxing. Anal. Calcd. for Pdc 22 H 22 N40 5 c1 2 : C, 44.06; H, 3 70; N, 9.3 4 Found: C, 44.28; H, 3.77; N, 9.32. Yield 0.34 g. B i s ( d i 2p y_r:1_9.y I am i n tlP l at i n um ( I I ) ch l or i de d i h yd rate [ Pt ( D PA) 2 ] Cl 2 2H 2 0. A solution of potassium tetrachloropl2tinate(I I) (1 .04 g,

PAGE 15

0.0025 mole) and di-2-pyridyl amine (0.855 g, 0.005 mole) in water and acetone (75 ml and 25 mi, respectively) was reflu xed for six hours. The tan sol id which remained was filtered out and discard e d. The filtrate was evaporated untJl crystal I ization began and the yellow sol id produced was washed with acetone and ether and air dried. A smal 1 amount of the final product was recrystallized from water. Anal. Calcd. for Ptc 20 H 22 N 6 o 2 c1 2 : C, 37.28; H, 3.44; N, 13.04. Found: C, 36.88; H, 3.42; N, 12.76. Yield 1.3 g. Bis(di-2-pyridylketon ehydra te)platinum(I I) tartrate tetrahydrate, potassium tartrate was added over a period of five minutes to a -4 solution of [Pt(DPKH 2 2 c1 2 H 2 0] (0.5 g, 7.3 x 10 mole) in water (20 ml). The white crystalline precipitate was filtered out and washed with acetone and diethyl ether. Anal. Ca led. for Ptc 26 H 32 N 4 o 14 : C, 38.09; H, 3.93; N, 6.84. Found: C, 38. 16; H, 3.88; N, 6.93. Bis(di-2-e_y_~l~tlketonehxirat~L~num(I I) tartrate, [Pt(DPKH 2 o) 2 ] c 4 H 4 o 6 This co~pound was prepared by heating a sampl e of [Pt(DPKH 2 o) 2 ] c 4 H 4 o 6 4H 2 0 for ten minutes at atmosph er ic pressure at 140C; a tempera ture obtained fr om the th e rmogravimetric a~alysis curve. Anal. Calcd. for Ptc 26 H 24 N 4 o 10 : C, 41 .77; H, 3.23; N, 7.50. Found: C, 41 50; H, 3.27; N, 7.20. Bis(di-2-pyridylket onehy drat e ) coppe r(II) chloride tetrahydrate, [Cu(DPKH 2 o) 2 (H 2 o) 2 ]c1 2 2H 2 0. A solution of di-2-pyridyl ketone (1.84 g, 0.01 mole) in hot water (30 ml) was added to a solution of copper(! 1) 5

PAGE 16

chloride {0.672 g, 0.005 mole) in water (20 ml). The resulting solution produced dark blue crystals upon standing. The blue material was filtered out, washed with acetone and diethyl ether, and air dried. Anal. Calcd. for CuC,2 2 H 28 N 4 o 8 cl 2 : C, 43.25; H, 4.60; N, 9.17. Found: C, 43.61; H, 4.65; N, 9.08. Yield 2.0 g. Bis(di-2-pyridylketonehydrate)copper(I I) sulfate hemihydrate, used to prepare the complex chloride, [Cu{DPKH 2 o) 2 (H 2 o) 2 ]cl 2 H 2 0. How ever, the product was heated at 130c for ten minutes before analysis, (a condition obtained from the TGA curve). Anal. Calcd. for Cuc 22 H 21 N 4 o 8 112 s: C, 46.11; H, 3.69; N, 9.78. Found: C, 46. 11; H, 3.88; N, 9.66. Yield 2.1 g. ~~~~:_2-P1~ i dy l ke tonehyd rate) copp~!J l.!.1 nitrate d Lt~yd rate, [Cu{DPKH 2 o) 2 (H 2 0) 2 ](N0 3 ) 2 The same method was used to prepare this compound as was used in the preparation of [Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0. The product was recrystallized from water. Anal. Calcd. for Cuc 22 H 24 N 6 o 12 : C, 42.07; H, 3.85; N, 13.38; Cu, 10.12. Found: C, 42.22; H, lf.00; N, 13.50; Cu, 10.18. Yieid 1.7 g. Di ch l orod i-2-pyr i dyl ketoned i-2:.2..Y..!:.~9.Y..!_ke!_~~hyd rate n l eke l ( 11) ~~y_drat~, {NiDPK(DPKH 2 0)Cl 2 ]2H 2 0. This material was prepared by the same method as [Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0. Anal. Ca led. for Nic 22 H 22 N 4 o 7 cl 2 : C, 47.86; H, 4.02; N, 10. 15. Found: C, 47.81; H, 3.84; N, 9.80. Yield 1.5 g. Dichlorobis(di-2-pyridylketone)nickili_.!_!l, [Ni(DPK) 2 cl 2 ]. The anhydrous chloride was prepared by heating [Ni(DPK)(DPKH O)Cl 2 ]2H 0 2 2 6

PAGE 17

at 180c in air at atmospheric pressure for 15 minutes. 1 +7 8 6 ; H, I, n.,. ~, 1 n 1 C:: I VL..' 11 J IV I ,_,1 9 Found: C, 47.81; H, 3.84; N, 9.80. Yield 1.5 g. Dichlorobis(di-2-e_y_sldylketone)nickel(II), [Ni(DPK) 2 c1 2 J. The anhydrous chloride was prepared by heating [Ni(DPK)(DPKH O)C1 2 ]2H Oat 2 2 J8o 0 c in air at atmospheric pressure for 15 minutes. Anal. Calcd. for Nic 22 H 16 N 4 o 2 c1 2 : C, 53.06; H, 3.24; N, 11.25. Found: C, 53.36; H, 3.26; N, 11 .39. Yield 1 .9 g. Bis(il:.~:.2.z'...!:~ketonehydrate)nickel{I I) nitrate monohydrate, Ni(DPKH 2 o) 2 (No 3 ) 2 H 2 0. The complex was prepared in this manner describ e d for [Cu(DPKH 2 0) 2 (H 2 0) 2 ]c1 2 2H 2 0. Anal. Calcd. for Nic 22 H 22 N 6 o 17 : C, 43.66; H, 3.66; N, 13.89. Found: C, 44.08; H, 3.99; N, 13.80. Bis(di-2-pyridylketone)~ickel(II) nitrate dihydrate, Ni(DPK) 2 (N0 3 )z2H 2 0. A sample of Ni(DPKH 2 0) 2 (N0 3 ) 2 H 2 0 ~vas heated for ten minutes at J4o 0 c in air at atmospheric pressure. Anal. Calcd. for NiC 22 H 20 N 6 o 10 : C, 45.00; H, 3.43; N, 14.32. Found: C, 45.04; H, 3.55; N, 13.92. Dinitratobis(di-~yridylketone)nickel(II) nitrate, [Ni(DPK) 2 (No 3 ) 2 ]. The anhydrous nitrate was prepared by heating a sa~ple of Ni(DPKH o) 2 (NO) HO for 15 minutes at 220c in air at atmospheric 2 3 2 2 pressure. Anal. Calcd. for NiC 22 H 16 N 6 o 8 : C, 47.94; H, 2.93; N, 15.25. Found: C, 47.64; H, 2.95; N, 15. 14. Di t h i oc ya na tob i s (di 2 ::Y..Ci it.l_ keton e 2-:2 i c k e 1 ( I I ) di hydrate, 7

PAGE 18

[Ni(DPK) 2 (NCS) 2 ]2H 2 0. A solution of ammonium thiocyanate (0.76 g, 0.01 mole) in \.Jater (50 m 1 \ Ill t / ~.:as added to a stirred solution of di-2pyridyl ketone (1 .84 g, .01 mole) and nickel(! 1) nitrate hexahydrate (1.45 g, 0.005 mole) in wat~r (80 ml). The precipitate W3S filtered out, washed with acetone and diethyl ether and air dried. Anal. Calcd. for Nic 24 H 20 N 6 o 4 s 2 : C, 49.76; H, 3.48; N, 14.51. Found: C, 50.22; H, 3.19; N, 14.74. Yield 2.4 g. Bis(di-2-pyridylketon e hydrate)nickel(l I) sulfate hemihydrate, Ni(DPKH 2 o) 2 so 4 l/2H 2 0. The same method used to prepare [Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0 was used to prepare the sulfate except that air dried material was additionally dried at 140c in air for 15 minutes. Anal. Calcd. for Nic 22 H 21 N 4 o 8 112 s: C, 46.50; H, 3.72; N, 9.86; S, 5.64. Found: C, 46.35; H, 3.69; N, 10.16; S, 5.71. Dichlorodi-2-pyridylketonedi-2-el!:_idylketonehydrate cobalt(! 1) dihydrate, [CoDPK(DPKH 0) Cl ]2H 2 0. The same method was used as was 2 2 2 used for [Cu(DPKH 2 0) (H 2 0) ]Cl 2H 0. 2 2 2 2 Anal. Calcd. for Coc 22 H 24 N 4 0 6 c1 2 : C, 47.84; H, 4.01; N, 10. 15. Found: C, 47.72; H, 4.02; N, 10.31. Yield 1.6 g. Dichlorobis(di-2-pyridylketone)cobalt(l I) chloride, [Co(DPK) 2 A sa~ple of [CoDPK(DPKH 2 0)Cl ]2H 0 was heated in air at atmos2 2 pheric pressure for ten minutes at 180c. Anal. Calcd. for Coc 22 H 22 N 4 o 5 c1 2 : C, 53.03; H, 3.24; N, 11.25. Found: C, 53.31; H, 3.27; N, 11.07 .QJ_thio~~nobis{di-2-e_yridylketone)cobalt(I I) monohydrate, [Co(DPK) 2 (NCS) 2 JH 2 0. The same procedure was used as in preparing [Ni(DPK) 2 (NCS) 2 ]2H 2 0. 8

PAGE 19

Anal. Calcd. for CoC 24 H 18 N 6 o 3 s 2 : C, 51.33; H, 3.23; N, 14.97. Found: C, 51.58; H, 3.U/; N, 14.24. Yield 2.5 g. Bis(di-2-e_y__r:idylketonehydrate)cobalt( 11)_ sulfate monohydr a te. A method analogous to that used in preparing Cu(DPKH 2 o) 2 so 4 1/2H 2 0 was employed. Anal. Calcd. for Coc 22 H 22 N 4 o 9 s: C, 45.76; H, 3.84; N, 9.71; S, 5.55; Co, 10.21. Found: C, Lr6.03; H, 3.75; N, 9.56; S, 5.80; Co, 10.26. Yield 1.9 g. To a solution of [Cu(DPKH 0) (H 0) ] 2 2 2 2 (N0 3 ) 2 (3.3 g; 0.005 mole) in boiling water (50 ml) was added to a solution of sodium carbonate (1.7 g, 0.016 mole) in hot water (10 ml). The resulting blue sol id was collected, washed with acetone and diethyl ether, and air dried. Anal. Calcd. for Cu 3 c 44 H 48 N 8 o 15 : C, 47.20; H, 4.32; N, 10.01; Cu, 17.03. Found: C, 1+7.16; H, 4.27; N, l0.2L~; Cu, 16.74. Yield 2.0 g. CuDPK07H 2 0. A solution of di-2-pyridyl ketone (i .84 g, 0.01 mole) and copper(II) nitrate hexahydrate (2.42 g, 0.01 mole) in boiling water (30 ml) was treated with a solution of sodium hydroxide (0.8 g, 0.002 mole) in water (10 ml). A dark blue solution phase separated but con verted to a blue sol id after standing overnight. The sol id material was filtered out, washed with acetone and diethyl ether, and air dried. Anal. Calcd. for Cuc 11 H 22 N 2 o 9 : C, 33.89; H, 5.69; N, 7.19; Cu, 16.30. Found: C, 33.71; H, 5.80; N, 7.18; Cl, 0.05; Cu, 16.37. Yield 2.3 g. PdDPK02H 2 0. The palladium compound was prepared by the same 9

PAGE 20

method as the cop pe r analog, CuDPK07H 2 o. Found: C, 38.42; H, 3.93 ; N, 8.26. Yield appro x i ma tely 2 g. J.2 g Co(DPKH 0) so 4 H O were dissolv e d in 2 2 2 85 ml of boiling water and the resulting solution was treated with an aqueous solution (20 ml) of sodium carbonate (1.2 g, 0.011 mole). Th e yello w crystal] in e sol id which form ed was washed with acetone and diethyl ether and air dried. Anal. Calcd. for Coc 22 H 19 N 4 o 4 1/2: C, 56. 18; H, 4.07; N, 11 .91; Co, 12.53. Found: C, 56.20; H, 4.12; N, 12.20; Co, l2.lf2; S, none. Co(DPK) 5 1/2H 0-3H+. 2.0 g Co(DP KH 0) SOHO were diss o lved in 2 2 2 2 4 2 hot water (50 ml) and the resulting solution cool ed to room temperatur e Addition of a solution of sodium hydrog e n carbonate (0.58 g, 0.007 ml) in cold water (15 ml) produced a r e d solution which deposited red-pink crystals on standing in an open v esse l for 36 hours. Anal. Calcd. for Coc 22 H 25 N 4 o 7 112 : C, 50.48; H, 4.62; N, 10.71; Co, 11.26. Found: C, 50.27; H, 4.82; N, 10.70; Co, 11.14; S, none. Yield appro x imately 1 .2 g. Dichlorobis(di-a-~1'..!:.liYlketon e )co~i.!Jl, [Cu(DPK) Cl ]. The 2 2 anhydrous copper chloride was pr epa red by the method used in pre pa ring [Ni ( DPK) l l 2]. Dinitratobisldi-2-pyridylk etone )coe..e.~ll, [Cu(DPK) 2 (NO) ]. 3 2 Se e the prep a ration of [Ni(DPK) (NO) ]. 2 3 2 10

PAGE 21

Aeearatus Gouy Balance. Magnetic susceptibility measurements were made using apparatus previously described (6). Procedures for cali bration, temperature control, and cryostat design have also already been described (7). A Cary Model 14 spectrometer was used in obtaining visible and near infrared spectra. Solid-state spectra were obtained using a Cary Model 1411 Diffuse Reflectance Accessory with magnesi~m carbonate as a reference material. A Perkin-Elmer Corporation Model 237B lnfracord recording spectrometer with a scale expansion accessory was used to obtain infrared spectra from L+OOO to 625 cm1 A Sargent Corporation Model SR recorder was used in con junction with the scale expansion accessory. Thermogravimetric Balance. The apparatus used was assembled from a Cahn Model G Electrobalance, a small Kerr furnace, a motor driven transformer, and a Minneapolis-Honeywell temperature bridge. Samples of approximately 0.040 g were suspended in the oven by means of a nichrome wire and weighed on the 0-0.010 g range of the balance using a 0.030 g counter weight. Molecular Wei_g_ht Apparatus. A Mechrolab Inc. Model 302 Vapor Pressure 0smometer was used. Several concentrations were run for a particular solute. Conductance Ap~aratus. Conductance measurements were made using an Industrial Instruments Model RC-18 Conductivity Bridge and a cell with a constant of 1.485 cm-I. All measurements were made at 25c; 11

PAGE 22

solvent conductivity was measured and subtracted from observed readings. X-ray Diffraction App~rat~. A Phillips Eiectronic Instruments Recording Diffractometer equipp e d with a c o pper target and a single crystal monochromator was used to obtain po w d e r diffraction data. 12

PAGE 23

RESULTS AND DISCUSSION The comple x es of di-J-pyridyl ketone involving Co(II), Cu(I I), and Ni(II) isolated from aqueous solution cont a in no more than two molecules of ligand in which one or both ketones contain a molecule of water of hydration (Stru c ture II I). Sol id-state composition and cationic structure of these comple x es are very depend e nt upon the nature of the anion present. Only the com ple x es of copper(! I) nitrate and copper(! I) chloride app e ar to contain the simple cation [M(DPKH 0) (H 0) ] 2 + in the sol id state. Furth e r, 2 2 2 2 the bis(di-2-pyridylketonehydrate) complexes exhibit acidic behavior, producing distinct compounds of varying compo s itions and structures 2when treated with bases such as Hco 3 co 3 and OH Comple x es prepared from Pt(I I) and Pd(ll) appear to be som e what more easily understood than those of th e first transition series and are therefore discussed first in order to u s e certain asp e cts of their beh a vior in for m ulating a model for use in understanding the nature of th e r e maining c om ple x es. The di-2-pyridyl ketone comple x es prepared from Pt(II) and Pd(II) (and one complex of di-2-pyridyl amin e ) are list e d b e low: [Pt(DPKH 0) ]CLH o 6 4H 0 2 2 4 2 13 [Pt (DPKH 0) Jc H 0 2 2 4 4 6

PAGE 24

[PtCl DPK] 2 [PdCl DPK] 2 [Pd(DPKH 0) ]Cl H 0 2 2 2 2 [Pt(DPA) ]Cl 2H 0 2 2 2 [PtCl DPA] 2 The symbol 11 DPK 11 is used throughout this dissertation to d e n o te di-2pyridyl ketone, 11 DPKH 2 0 11 its hydrate, and 11 DPA 11 di-2-pyridyl amine The co m pounds are of two types, the anhydrous mono(di-2-pyridylketone) co m ple xe s (PdCl DPK) a n d the hydrated bis(di-2-pyridylketone) comple x es 2 ([Pd(DPKH 0) ]Cl H 2 0). 2 2 2 Hydration of the ket o ne carbonyl should remove th e C = 0 stretching band found in the infrared spectrum of [PtDPKCl 2 ] (Figure le) (1680 cm1 ) which in g e neral is quite similar to the spectrum of the free ligand (Figure ld). Indeed the spectrum of [Pt(DPKH 0) ]Cl H 0 2 2 2 2 (Figure lb) exhibits no band at 1680 cm-l and a general lack of similarity to the free liga n d spectrum is evident. In 2dditi o n, a -1 very br oa d band is pres e nt around 3000 cm 1n the 0-H and C-H stretching region which is co m mon for hydrogen bond e d mat e rials. If [Pt(Pd)(DPKH 0) ]Cl 4H 0 is heated to 250c, a molecule of 2 2 2 2 ligand and all six water molecules are lost and Pt(Pd)CllPK is formed. The details are displayed in the therm o gravim e tric analysis curve shown in Figure 2. The weight losses correspond closely to the p~ocesses indicat e d and the infrared spectrum of the m a terial heated to 220c matches that of [PtCl 2 DPK] prepared in aqueous solution. It can be seen in Figur e 2 that not all of the w ater m o lecules are lost simul taneously. Figure la shows the infrared spectrum of an inter me diate monohydrate (pr e pared by heating at 120c for ten minutes), and suggests 14

PAGE 25

w u z <( II I 4000 3000 2000 1000 FREQUENCY (cm1 ) Figure 1.-The infrared spectra of: (a) ,[PtDPK(DPKH O)]Cl ; 2 2 {b) ,[Pt(OPKH 0) ]Cl 4H O; (c) ,[PtDPKCI ); (d) ,DPK. 2 2 2 2 2 15

PAGE 26

I I 5H6 2HO 2 2 16 b -----------------100 t C 0 200 1DPK t PtDPKCI 2 ( 300 Figure 2.-The TGA curves for: (a) ,[Pt(DPKH 0) ]Cl 4H O; {b),[Pt(DPA) 2 ]Cl 2H 2 0. 2 2 2 2 2

PAGE 27

a transient comple x containing both a hydrat e d 1 igand and an unhydrat e d -1 1 igand; the band at 1680 cm supports the existence of th e anhydrous -1 ketone and the broad band arnu n ci 3000 cm th e hydrated one. Such mixed co m plexes are isolated from aque o us solution in comple xe s of nickel and cobalt (to be discussed lat e r). The ccxnplex, [PtCl DPK] resists hydration (or even solution) 2 upon prolonged refluxing in water. This fact s ee ms unusual since only hydrated platinum or palladium compounds containing 'two molecules of 1 igand are is~lated and since attempts at thermal d e hydration result in the loss of water followed by im me diate loss of a mol e cule of 1 igand at the relatively low temperature of 220c (Figure 2). The analog o us chlorides of Ni(II), Cu(II), and Co(II) are readily deh y drat e d and the anhydrous chlorides are stable over a range of nearly 100c with co m plete decomposition at almost 300c (Figure 3). Inspection of a model (Framework Molecular Models, Prentice Hall, Inc.) of the anhydrous bis(di-2-pyridylketon e ) c o ~plex sugg e sts a reason for its thermal instability and also a reason for th e sta b ility of its hydrates. In building the model, the following restri c tions were imposed: [1] Pt(II) (or Pd(II)) has only four coordinate bonds 1n which all nucl e i, donor atoms and the m e tal atom, are located 1n the same plane (all kn ov, m Pt(II) and Pd(II) comple xe s are four-coordinate and planar); [2] Di-2-pyridyl k e tone (or its hydrat e ) forms only tw o coordinate bonds involving only the pyridine nitrog e ns as donors; [3] a conform a tion of the free l igan~ allo w ing planarity of all atoms in 17

PAGE 28

lI (.9 w s: \ 20 100 200 Figure 3.-The TGA curves for: (a) ,[Cu(DPKH 0) (H 0) ]Cl 2H 0; 2 2 2 2 2 2 {b) ,[CoDPK(DPKH 2 0)Cl 2 ]2H 2 o. 18 300

PAGE 29

di-2-pyridyl ketone and therefore maximum resonance interaction of rr symmetry orbitals is favored. Figure 4 sh ows a sketch of a model of the bis anhydrous co mp l ex which indic ates that hydrog en atoms on differ en t 1 igands interact across the donor-m et al pla ne Such interactio n would either weaken the coordinate bonds by preventing clos e approach of the donor atoms to the metal atoms or require some sort of distortion from planarity, or both. But a strained condition can be eliminated in either one of two w ay s: [1] by elimination of one 1 ig an d followed by coordination of monodentate 1 igands which present no steric pro b l em s (as in the case of the format ion of [PtC 1 2 DPK] at 220c); [2] by h y dration of one or two ketone carbonyls, which according to the model eliminates all interaction (Figure 5). As is seen in the photograph of the Prentice Hal 1 models (Figure Sa, b), hydration chang e s the bond angles of the bridging carbon ato~ from the sp 2 angle to the tetrah e dral angle and,as a result, a 11 boat 11 configuration is possible in which th e pyridine rings are canted out of the coordinate plane (a chair configuration would require distortion of the individual pyridine rings). No hydrogen atom interaction is indicated sinc e the two ((-hydrogens of one ligand are slanted do wnw ard and those of the other upward (Figure Sb). Figure Sc sho ws the proposed structure for the monohydrate, [Pt(DPKH O)DP K] Cl 2 2 prepared by he at ing [Pt(DPKH 0) ]Cl 4H Oat 120c for ten minutes. One 2 2 2 2 ketone is hydrated; hence its pyridine rings are not coplanar and their c{-hydrog en s extend above the anhydrous plan ar ketone,with the result that no steric interaction betw een the two ligand molecules is evident. 19

PAGE 30

Fi g ur e 4.-Th e n a tur e of t he pr opose d s t e ric i nte r ac ti on acro ss t he c oor din a t e pl ane of [Pt(D PK ) ] Cl 2 2 20

PAGE 31

C b a Figure 5.-Prentice-Hall models of: (a), The 11 boat 11 configuration formed by di-2-pyridyl keton e hydrate in complexes; {b) ,[Pt(DP K H 2 o) 2 J 2 +; {c) ,[PtDPK(DP K H 2 o)] 2 +. 21

PAGE 32

The important conclusion drawn from the above discussion is that hydration of the ketone carbonyl in complexes of Pd(l1) and Pt(I I) occurs because considerable inter] igand steric interaction destabilizes the ketone carbonyl, which adds a molecule of water with the result that a strain-free, non-interacting, cyclohexanc-1 ike boat configuration is formed. lhe type of steric interaction discussed in connection with the anhydrous bis(di-2-pyridylketone)platinum(I I) chloride is apparently not 1 imited to di-2-pyridyl ketone complexes. The analogous 2, J dipyridine compound, Pt(dipy) Cl is not stable in crystal 1 in c < r"l,1 but 2 2 it is reported to exist in solutions containing excess I igand ( 8) 1 ,10 phenanthroline exhibits similar behavior. How e ver, both 1 ig ands form solid complexes with Pt(II) and Pd(II) containing two molecules of ligand if the anion involved is c10 4 PtCl~or (8). In contrast to the bis complex a model of [Pt(Pd)Cl DPK] 2 sugg e sts that no steric interaction' is present to promote hydration. In addition, electronic stabilization of the ketone form may also be a factor in the absence of hydration in the mono-compounds. One resonance forrn is shown below which illustrates a possible stabilizing e l ectronic inter action. The complex e s prepared from the first row transition m e tals consid ered are of two types: complex metal salts and neutral complexes (containing DPKOHand/or DPK0 2 -). Of the two types, the salts exhibit 22

PAGE 33

the more regular behavior and are more completely characterized by av~i1ab1~ methods. Since -:. ..... --.1\JC"':C"' "-F V IIU I 1--' I .J ....... their behavior is essential to an understanding of the nature of the neutral complexes, the complex salts wil 1 be discussed fir~t,with special attention directed to war d influence of the anion present. _!:()mp l ~x S a l ts of _f u ( I I ) Of al 1 the complex hydrates prepared from salts of copper, nickel, and cobalt shown below, only the nitrate and chloride of copper appear 2+ to contain th_e simple cation, [Cu(DPKH 2 0) (H 0) ] in th e sol id state; 2 2 2 all others have too little water for the diaquo cation to exist. Cu(DPK) Cl 6H 0 2 2 2 Ni ( DPK) C 1 3H 0 2 2 2 Ni(DPK) 2 (NO) 2H 0 3 2 2 Co(DPK) Cl 3H 0 2 2 2 Cu(DPK) (NO ) 4H 0 2 3 2 2 Ni (DPK) (NO ) 3H 0 2 3 2 2 Ni (DPK) (NCS) 2H 0 2 2 2 Co(DPK) SO 3H 0 2 4 2 Cu(DPK) SOL2 l/2H 0 2 f 2 Co(DPK) (NCS) H 0 2 2 2 Comparison of the infrared spectra of Cu(DPK) Cl 6H O and Pt(DPK) Cl 6H 0 2 2 2 2 2 2 23 (Figure 6) suggests that the structure of the complex cation is essentially the same in both cases, since in this particular system infrared spectra are very sensitive to structural arrangem e nts. As will be seen later, some compounds give infrared spectra characteristic of both hydrated and anhydrous ketones, some lack the broad 0-H stretching absorption and others show no absorptions characteristic of the hydrated ketone.

PAGE 34

Q) u C ,,, E Ill C ,,, L I24 C I 4000 3000 2000 1000 Figure 6.-The infrared spectra of: (a) ,[Pt(DPKH 2 0) ]Cl 4H O; .. 2 2 2 (b) ,[Cu(DPKH 2 o) 2 (H 2 0) 2 ]Cl 2 2H 2 0; (c) ,[Cu(DPK) 2 cl 2 ].

PAGE 35

It will be recalled that the cation structur~ proposed for the platinum compound consists of planar coordination of the four pyridine nitrogens in such a fashion as to produce a boat configuration free from strain and steric interaction {Figure 5). Such a structure modified to include two trans water molecules is proposed for the solid complexes of copper nitrate and copper chloride. Additional support for this type of tetragonal structure is given by the position of the absorption maxima in the sol id state visible spectra (5180A 0 for [Cu(DPKH 2 o) 2 (H 2 o) 2 J Cl 2 2H 2 0 and 5450A 0 for [Cu(DPKH 2 o) 2 (H 2 o) 2 J(N0 3 1) and in aqueous solution by both the position of the maxima and the magnitude of the extinction coefficients {56lOA 0 E =37 for [Cu{DPKH 2 o) 2 (H 2 o) 2 Jcl 2 2H 2 0 and 5650A 0 =37 [Cu{DPKH 2 0) (H 0) 2 ]{NO) ). {See the section on visible spectra.) 2 2 3 2 More nearly octahedral structures produce maxima at lower energy and o [ 2+ of lower intensity (e.g., 8300A, E =ll for Cu{H 2 o) 6 J ). In Figure 7, the positions of the visible absorption maxima for the copper complexes are arranged according to the energy of the respective transitions. Shifts of varying magnitudes are evident from sol id state to solution and a pronounced concentration effect is observed for aqueous solutions of all three complexes. Both the nitrate and the chloride have absorp tions of the same energy in the sol id state and absorptions of approxi mately equal energy in the more concen~rated aqueous solutions. This parallel spectral behavior indicates that both the nitrate and the chloride have equivalent structures in the solid state and in aqueous solution. An explanation of the spectral concentration dependence of 25 both compounds in aqueous solution is provided by the following observations:

PAGE 36

-3 o 5x10 -4 0 5x10 6500 -4 4 x10 -3 6 x10 -4 -4 6000 x10 4x10 -3 5 x10 -3 9x 1-0 4 5x10 I : 4X10 3 3 -4 -3. 5x10_g-5x10 4 ~10 3 4x10 0 2x10 3 5500 ct.) + + ')_ ( Cl-) ( N0 3 ) ( SC ) a b C 0 ,inCH 3 oH 1n H 2 O + Solid I Figure 7.-The positions of the absorption maxima of: (a) ,[Cu(DPKH 0) 72 (H 2 o) 2 ]Clz2H 2 0; (b),[Cu(DPKH 2 0) 2 (H 2 o) 2 ](N0 3 ) 2 ; (c), Cu(DPKH 2 o) 2 s 4 1/2H 2 0. (The nu m erical values indicate conc e ntration in m oles per 1 iter.) 26

PAGE 37

[l] addition of a strong acid mo ves th e absorption ma x ima of dilute solutions to high e r energies than that of even the concentrat e d soluti on s, [2] the conductivity of both complexes appro x imates that of a di-uni electrolyte (9, p. 339) at high concentrations but deviat e s mark e dly toward high e r values at low concentration {Figure 8), [3] addition of ba s e to aqueous solutions of either the nitrate or chloride produces an anion-free, deprotonat e d complex (to b e discussed in a later section). An explanation consistent with the a b ove observations is that within the sol id state of both the chloride and the nitrate salts, the cation, [Cu(~P K H 2 o) 2 (H 2 o) 2 ] 2 : exists which in solutio n b e hav e s as a weak acid. Thus at low concentrations sufficient conjugate base is present to shift the observed peak to lower energies. An attenda n t increase in conductivity in aqueous solution at low concentration is seen for the above co m plexes in Figur e 8. For strong electrolytes, molar conductance is a 1 in e ar function of c 112 (C= concentration) and such behavior is obs e rv e d for [Pd(DPKH 2 o) 2 ]cl 2 4H 2 shown on the same chart. That the palladium comple x reveals less acid character suggests that coordination of more than four do n or atoms is important in the ionization process of analog o us copper compound s and that the e x tra donors are possibly deproton a ted hydro x yl gr o ups brought into proper spati a l r e lationship by cond e nsation of tw o or m o r e conjugat e bases. Figure 9 shows in a more quantitative fashion th e eff e ct of acid on dilute aqueous solutions of [Cu(DPKH 2 o) 2 (H 2 o) 2 ]c1 2 4H 2 0. A 3.8 -4 x 10 m solution in a ten-centimeter cell (30 ml) e x hibits a br oa d 27

PAGE 38

300 ------------------MgCl 2 250 -200 .0 2 04 Cl/2 .06 .08 Figure 8.-The,molar conduct1vlt1es In water of: (a),[Pd(DPKH 0) ]C1 2 4H 0; (b), 2 2 2 [C~(DPKH 2 0) 2 (H 2 0) ](No 3 ) ; (c) ,[Cu(DPKH 2 0) (H 0) ]Cl 2H 0. 2 2 222 22

PAGE 39

UJ u z <( co 0::. 0 V'I co <( 4 5 6 7 8 9 10 WAVELENGTH (A 0 x 10-3) Figure 9.-The solution spectra (H 2 0) of [Cu(DPKH 2 0)(H 2 o) 2 Jcl 2 2H 2 0: (a), 3,Sxl04 m; {b), 3,Sxl04 m with 3 drops 30% perchloric acid in 30 ml; (c), 3.8xJ04 m with JO drops perchloric acid in 30 ml.

PAGE 40

absorption with a maximum at 6320A 0 As shown in the figure, addition of 30% perchloric acid in successive amounts of three and ten drops shifts the maximum to nearly 5000A 0 and produces a maximum of lower intensity at approximately 7000A~ indicating that the acid activity of the complex is surpressed and that the major absorbing species is the diaquobis(di-2-pyridylketonehydrate)copper(II) cation. If perchloric acid in iarger amounts is added to more concentrated solutions of the copper nitrate and copper chloride complexes, a peak at about 8300A 0 appears, indicating that the hexaaquo species is formed. Little effect of concentration on the position of the complex nitrate absorption maximum in methanol solutions is observed; however, the C()ll)plex chloride absorption is quite concentration-dependent. (Representative spectra are shown in Figure 10.) No substantial difference between the spectrum of [Cu(DPKH 2 o) 2 (H 2 o) 2 ](N0 3 ) 2 in methanol and that of an aqueous solution of [Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 4H 2 0 is observed, indicating that methanol solutions of the nitrate contain the same complex as the aqueous solu tions or at least a quite similar one. On the other hand, the spectrum of a methanol solution of the chloride is quite distinct, having a much greater width. Such a spectrum is perhaps due to coordination of one chloride ion as suggested by the conductivity data (Figure 11) to form the cation, [Cu(DPKH 2 0) 2 ClH 2 0]+. Figure 11 shows conductivity data for the chloride and nitrate in methanol together with those for the anhydrous chloride. The behavior of the nitrate approximates that of a di-univalent electrolyte at high concentrations with devi3tion toward 30

PAGE 41

4 5 6 7 8 9 10 WAVELENGTH (A 0 x 10-3) -3 Figure 10.-The solution spectra of: (a),[Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0 in water (2 cm cells) 3.BxlO m; (b), [Cu(DPKH 2 o) 2 (H 2 o) 2 ](N0 3 ) 2 in methanol (2 cm cells) 3.0xlo3 m; (c) ,[Cu(DPKH 2 o) 2 (H 2 o) 2 ] c1 2 2H 2 0 in methanol (2 cm cells) 3.6x10-3 m.

PAGE 42

I (\) 0 E N E u I E .!: 0 (1) u C Ct) u :, -0 C 0 u Ct) 0 ::,: 200 150 f Cs C I ; Mg (C N S ) 2 = 2 4 0 10 0 t ___ __._ __ ...__ _.,,_ ___. __ _._ __. __ __.._ __ _.1., ____, .02 .04 Cl/2 .06 .08 Figure ll.-The molar conductivities In methanol of:(a),[Cu(DPK) 2 c1 2 : ; (b) ,[Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0; (c),Cu(DPKH 0) (H 0) ( N O) 2 2 2 2 3 2 w N

PAGE 43

lower molar conductivity at lo we r conc e ntrat ions whereas the behavior of the hydrated chloride is consistent with that of a uni-univalent electro lyte with similar deviation obs e rved at low concentration (9, p. 357-8). To recapitulate briefly, the cation, [Cu(DP K H 2 o) 2 J 2 ~ exists in concentrated aqueous solutions and behaves as an acid at low concentra tions, producing condensed structures upon ionization. In methanol solutions, however, coordination of chloride ion (and not nitrate ion) + occurs (Figure 11) to produce the cation [Cu(DPKH 2 o) 2 ClH 2 0] or its methanol solvate. Formation of the m e thanol solvate is probable in the case of the hydrated chloride, since both the hydrated and the anhydrous chlorid e have almost identical electrical and spectral properties in methanol (Figure 11). Ketal formation is the most probable reaction and would app e ar to proceed to approximately the same e x tent w!th eith e r complexes of th e anhydrous ketone or their hydrates. Unlike their hydrates, the anhydrous copper nitrate ([Cu(DPK) 2 (N0 3 ) 2 ]) and chloride ([Cu(DPK) 2 ci 2 J) most 1 ik e ly have cis structures with the anions coordinated in the sol id state; a trans structure does not appear reasonable in view of the steric problem discussed earlier. Evidence supporting coordination of the nitrate ion is found in the infrared spectra. Figures 12 and 13 show parts of the infrared sp ec tra for [Cu(DPK) 2 ci 2 J and [Cu(DPK) 2 (No 3 ) 2 J. The two spectra should b e very much alike except for bands produced by the nitrate ion. Inde e d, a general similarity is observ e d in the spectra shown and in other regi o ns -1 -1 not shown (App e ndix C), except for two bands at 1310 cm and 1400 cm and a third at 1040 cm-l 33

PAGE 44

w u z < I::c V, z <( a:: I1400 1300 Figure 12.-The infrared spectra of: (a) ,Cu(DPK) 2 (N0 3 ) 2 ; (b) ,Cu(DPK) 2 (C1) 2

PAGE 46

Uncoordinated nitrate has only one band near 1400 cm-l that splits into t~o upon coordination, one at l530-148u cm-I, and one at 1290-1250 -1 cm (10, p. 161). In addition, a band infrared inactive in N0 3 appears as a result of coordination at 1235-970 cm-l and two other bands of lower intensity are also observed. The spectrum of the anhydrous nitrate (Figures 12 and 13) has three of the bands (1310, 1400, and 1040 cm1 ) associated with coordinated nitrate, although the splitting of the N-0 stretching band is not as great as reported by Nakamoto (10). However, greater splitting in the anhydrous nickel nitrate (to be discussed later) is observed, perhaps due to a stronger interaction between Ni(II) and nitrate ion (a reasonable conclusion since Ni(II) is less inclined than Cu(I I) to form four-coordinate complexes). Two nitrate bands can be assigned but they are of low intensity and the chance of their being obscured by the complicated organic ligand spectrum is quite great. The visible spectra of the anhydrous copper nitrate and chloride (Figure 14) are almost identical, indicating that chloride, as well as nitrate, is coordinated. Chloride ion and nitrate, although they form relatively weak donor bonds, are not far removed from one another in the spectrochemical series and would be expected to produce equivalent spectra in such a system as that described above. In attempting to suggest structures for the remaining complex salts, one observation must be kept in mind: regardless of the anion in volved (except for the insoluble thiocyanates), complex e s of a particular metal produce id e ntical visible spectra in aqueous solution, no matter how great the variation in the corresponding sol id-state spectra. A 36

PAGE 47

5 6 7 8 9 WAVELENGTH (A 0 x 10-3) Figure 14.-The solid-state absorption spectra of: (a) ,[Cu(DPK) 2 c1 2 J (diffuse reflectance); (b), [Cu(DPK) 2 (No 3 ) 2 J (Nujol mull); (c) ,[Cu(DPKH 2 0) 2 (H 2 0) 2 Jc1 2 2H 2 0 (diffuse reflectance). 10

PAGE 48

common coordination polyhedi-on, therefore, exists in aqueous solution for the complexes of a particuiar metal and indeed for complexes of all three metals. (See the section on visible spectra.) Conductivity data (Figures 8 and 18) establish that this common species is ionic and that the cation is divalent. In the case of aqueous solutions of the copper chloride and nitrate, a trans-diaquo complex was proposed earlier and in the next section evidence is presented in support of a trans structure for the analogous nickel cations in aqueous solution. Having established that all complexes form a common cation in aqueous solution, the problem becomes one of understanding variations in solid-state struc:ture and the following discussions will be directed toward that objective. Come lex Salts of Co(I I) and Ni(I I) The chlorides of Ni (11) and Co(I I) have the composition, M(DPK) 2 C1 2 3H 2 0 and, although prepared in aqueous solution, contain only one hydrated ketone. Figure 15 shows the infrared spectra for the hydrated nickel and cobalt chlorides. The two spectra are identical with a carbonyl band at 1680 cm-l and a broad 0-H stretching band occurring -1 near 3000 c m In the hydrated chlorides, two strong bands are present -1 in the region of the highest energy pyridine band (1605 and 1590 cm ). -1 The band below 1600 cm is associated with the anhydrous ketone as in the spectrum of [Ni(DPK) 2 c1 2 ], whereas the band above 1600 cm-I is associated with the hydrated ketone as in the spectrum of[Cu(DPKH 2 o) 2 J Cli2H 2 0. 38

PAGE 49

( ,n, I' i i j jl 4000 3000 2000 1000 FREQUENCY (cm1 ) Figure 15.-Thc inf~ared spectra of: (a) ,[C~(DPKH 2 o) 2 (H 2 o) 2 Jct 2 2H 2 0; (b) ,[NiDPK(DPKH 2 0)C1 2 ]2H 2 0; (c) ,[CoDPK(DPKH 2 0)Cli]2H 2 0; ( d) [Ni ( DPK) 2 Cl 2 ] 39

PAGE 50

Additional areas throughout the chloride spectrum also appear to result from a superpositioning of the spectra of a hydrated ketone and an anhydrous ketone. The reason such a 11 hemihydrate 11 should precipi tate from water is not cornp letely clear ,tlthough coordination of chloride ion see:ns 1 ikely, in which case hydration could be prevented by steric hindrance. Molecular models indicate that in the trans chloroaquo complex one hydroxyl group would interact with a coordinated chloride ion. A similar interaction is indicated in a dichloro complex containing two hydrated ketones. However, no steric interaction is indicated if one 1 igand is anhydrous and planar in a trans complex containing one chloride ion and one water molecule as seen in Figure 16a. In Figure 16a, the bottommost group is a chloride ion and the top one a water molecule. A cis-dichloro configuration with one anhydrous ketone (Figure 166) is also free of steric interaction and indeed such a structure for the nickel (and cobalt) chloride trihydrate is supported by the visible spectra. As seen in Figure 17, the spectrum of [NiDPK(DPKH 2 0) Cl 2 ]2H 2 0 shows a close similarity to the spectrum of [Ni(DPK) 2 c1 2 J; the latter is expected to have a cis structure as discussed earlier in connection with the copper chloride and nitrate. Both spectra are consis t ent with approximate octahedral geometry (see the section on visible spectra). A 1rans-monochloro a quo structure is unlikely for the sol id nickel (and cobalt) chloride hydrates because methanol solutions con taining uni-univalent electrolytes (Figure 18) (and presumably a 40

PAGE 51

b a + Figure 16.-Prentice-Hall mod e ls of:(a), trans-[NiDPK(DPKH 2 0)H 2 0Cl], with one hydrog en bond shown; {b), ~l2_-[NiDPK(DPKH 2 0)Cl 2 ]. 41

PAGE 52

I.LI u z
PAGE 53

...-.. I V 0 E N I E u I Ill E .c 0 ......., V u C: IU +-' u :, "O C: 0 u L II;) 0 ::t: Mg Cl 0 2 1 2 r-... :... 200~ .... 100 -----CsCI CH OH I 3 ----'----~ ---_!_ __ _._ cl/2 02 .04 .06 fjgure 18.Th C! molar condl1 c tivities in methanol of:(a),[CoDPK(DPKH 2 o) C1 2 ]2H O; (b),[NiDPK(DPKH 2 0)C1 2 ]2H 2 0; (c),Ni(DPK) (N0 3 ) 2 2 2 3H 2 0; and in water of: (d) ,Ni(DPK) 2 (N0?) 2 3H 2 0; (e), .J [NiDPK(DPKH 2 0)C1 2 ]2H 2 0; (f),[CoDPK(DPKH 2 0)C1 2 ]2H 2 0. 43

PAGE 54

trans-monochloro complex) exhibit spectra (Figure l?a, b) virtually identical to those of aqueous soiutions but quite uniike those ex hibited by the sol id, [Ni (DPK)/1 2 ], and its sol id hydrate. The canplex of nickel(I I) nitrate and di-2-pyridyl ketone isolated from aqueous solution is the trihydrate, Ni(DPK) (NO) 3H 0. 2 3 2 2 Its infrared spectrum shows no carbonyl band (Figure 19), and only one band near 1400 cm-l (1385 cm1 ) characteristic of uncoordinated nitrate ion (Figures 19 and 20). The corresponding band in the spectrum of I sodium nitrate I ies at 1405 cm Although a trans-diaquobis(di-2pyridylketonehydrate)nickel(I I) cation with ionic nitrate ions would indeed produce an i~frared spectrum with the above features, only three of the four requisite water molecules are present in the complex, two of which are involved in the hydration of the two ketone carbonyls. The thermogravimetric analysis curve shown in Figure 20 indicates that only three molecules of water are present and that the trihydrate has an adequate stability range to permit accurate analysis. The sol id state visible spectrum of this complex further confirms that a simple diaquo species does not exist in the sol id. As seen 1n Figure 21, the visible spectrum of the sol id is quite distinct from the spectra observed for aqueous solutions of all three nickel complexes, each of which does contain the diaquo cation. Thus, for the sol id trihydrate, a polynuclear structure is proposed which would involve coordination of the oxygen atoms of hydroxyl groups as bridging units. Complete dehydration of the trihydrate, Ni(DPK) 2 (NO) 3H O,at 3 2 2 220c produces a complex containing coordinated nitrate ions (Figures 44

PAGE 55

IJJ u :z o:( ~ nj l\ r \ ( 1.-.q r ; ( i; I \ : I I 1\ I l ,1 1 1 I I /11 I f 1 jl H I 1 I I I I -. ( I 1I l 11 \~ 1 !I f I J ri l--------'-~_.._l _1 ___ L__1 __._____._..._I --'--1 ___.._____J_____a__L _.________,___ 4000 3000 2000 1000 FREQUENCY (cm1 ) Figure 19.-The infrared spectra of: (a) ,[Cu(DPKH 0) (H 0) ]Cl iH O; 2 2 2 2 2 2 (b) ,[~i(OPK) 2 (N0 3 ) 2 ]; (c), Ni(OPK) 2 (N0 3 ) 2 2H 2 0; (d), Ni(DPKH 2 o) 2 (No 3 ) 2 H 0 2 45

PAGE 56

46 -I ________ H 2 0 ____ 2HIO 2 20 100 t, C 0 200 300 Figure 20.-The TGA curve for: Ni(DPKH 2 o) (NO) H 0. 2 3 2 2

PAGE 57

UJ u z <( a:) 0::: 0 V'> a:) <( 5 6 7 s g 10 WAVELENGTH (A 0 x l o-3) Figure 21.-Nujol mull spectra of: (a), Ni (DPK) (NO ) ; (c), Ni (DPK) 2 (NO ) 2H O; (d), Ni (DPK) (NO ) 3H O; 2 32 32 2 2 32 2 and the solution spectrum (H 2 o, 5.lxl0-3 m 10 cm cell) of: (b), Ni(DPKH 2 o) (NO) Ho. 2 3 2 2

PAGE 58

19 and 22) characterized by infrared bands at 1450 cm-l, 1285 cm-l and 1020 cm-l. A cis-dinitrato structure analogous to the copper(i i) nitrate complex is proposed. An intermediate dihydrate is formed at 120c (Figure 20), whose infrared spectrum (Figures 18 and 23) shows bands arising from b0th a hydrated ketone and an anhydrous ketone. In addition, only one nitrate ion appears -1 1285 cm and 1020 i to be coordinated (infrared bands at 1440 cm -1 cm ); the other nitrate ion appears to be un-1 coordinated (one band at 1380 cm ) The following structure is thereH2 N0 3 ON0 2 The visible spectra of the three sol id nitrates discussed above show additional comp] ications not observed in the spectrum of the complex nickel chlorides and will be discussed more fully in the later section on visible spectra. The complex thiocyanates, [Ni(DPK) 2 (NCS) 2 ]2H 2 0 and [Co(DPK) 2 (NCS) 2 JH 2 0 prepared show no indication of ketone hydration and accord ingly a carbonyl band is seen in the infrared spectrum of each compound (Figure 24). The water in each compound p~oduces an absorption at 3400 cm-l quite distinct from the type of band observed in the complexes of hydrated ketones (Figure 15a). The infrared bands observed for the thiocyanate ion are those characteristic of coordinated thiocyanate -1 -1 1 inked to the metal through nitrogen, 2075 cm and 800 cm The 48 values observed are within the ranges established by Nakamoto (10, p. 173), 2150-2080 cm-l and 810-690 cm-l

PAGE 59

LJ.J u z c:( f~ V'> z 1400 1300 FREQUENCY (cm1 ) Figure 22.-The infrared spectra of:(a),[N!(DPK} 2 (N0 3 ) 2 J; (b),[Ni(DPK) 2 ct 2 J.

PAGE 60

UJ u z <( f1400 -1 FREQUENCY (cm ) 1300 Figure 23.-The infrared spectra of:(a),Ni(DPK) 2 (N0 3 )/H 2 0; (b), Ni(DPKH 2 0) 2 (N0 3 ) 2 H 2 0; (c),[Cu(DPKH 2 0) 2 (H 2 0) 2 ]Cl/H 2 0. V, 0

PAGE 61

w u z c:{ IV'> z I51 Jr I. i 11 I I I 1 I 4000 3000 2000 1000 FREQUENCY (cm-I) Figure 24.-The infrared spectra of: (a) ,[Ni (DPK) Cl ]; {b) ,[Ni (DPK) 2 2 2 (NCS) 2 ]2H 2 0; (c) ,[Co(DPK) (NCS) ]H 0. 2 2 2

PAGE 62

The visible spectrum of the nickel complex is consistent with an approximately octai1eclrcil dffdng emen t of donor atoms about the metal ion. The cobalt(I I) thio~yanate is isomorphous to the analogous nickel compound, as seen from the X-ray diffraction ddta (Table 1). The three complex sulfates investigated, Cu(DPK) 2 so 4 2 l/2H 2 0, Ni(DPK) 2 so 4 2 l/2H 2 0, and Co(DPK) 2 so 4 3H 2 0 produce very similar infrared spectra (Figure 25), exhibit similar thermogravimetric behavior (Figure 26), and, according to X-ray diffraction data, are indeed isomorphous (Table 2). All three compounds were analyzed and investigated after having been heated for ten minutes at 200c (Figure 26) to remove a small amount of nonstructural water (the infrared spectrum of th e unheated material matched exactly the spectrum of the heated material). Figure 25 sho\'JS the infrared spectra of the three complex sulfates which differ considerably from the spectrum of [Cu(DPKH 2 o) 2 (H 2 o) 2 ]cl 2 2H 2 0 included for comparison. The broad 0-H band is replaced -1 by several absorptions spread out over almost 2000 cm the bands arising from C-H linkage are observed in the sulfates, and only t~vo -1 bands are obs er ved near 800 cm in the sulfates, whereas three are present in the complex copper(I I) chloride spectrum. The dissimilarity of the two classes of spectra indicates that the simple diaquobis(di-2-pyridylketonehydrate)metal{I I) cation does not exist in the sulfates. 52

PAGE 63

53 Table 1 X-Ray Dif f ra ct i o n D ata : 28 V a lu es an d Re i ati v e i ntens i ties [Co(D PK ) (NCS) ]H 0 2 2 2 [Ni(DP K ) (NCS) ]2HO 2 2 2 28 R e 1. Int. 28 R e l. Int. 7 38 0. 19 7 38 0. 2L f 1 O .4 6 0. 4 1 10.li 6 0.52 12 00 o.42 11.98 0.42 12.28 1.00 12 29 1.00 13.20 0.28 13.20 0.30 16. 34 0.35 16.34 0.3 6 18.7 6 o. 15 18.76 0. 12 20.70 0.22 20.8 0 0. 15 23.20 0.49 23.2 4 0 Lf] 24.00 0. 6 3 24 00 0. 6 3 26.00 0 .lf2 26.02 o.45 26 72 0 50 26.74 0. 6 0 33 40 0. 1 lf 33.40 0. 10 35. 1 6 o. 14 35. 16 o. 11 39 18 0. 10 39.20 0. 10

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54 Table 2 XRay Diffraction Data: 29 Values and Relative Intensities Cu(D P K) 2 so 4 H 2 0 Co(DPK) so 4 2 H 2 0 Ni (DPK) lo 4 H 0 2 28 Rel. Int. 28 Rel. Int. 20 Rel. Int. 9.4 .81 9.7 675 9.5 .43 12.3 .56 12.6 .59 12.2 .53 12.8 l.00 13.0 l.00 12.5 .80 15.7 .57 15.9 .52 15.5 .48 16.3 16 16.3 .19 17 .8 18 17.5 .21 17. 7 .18 18. l 17 18.0 17 19.9 .30 20.2 .38 19.9 .24 20.4 .42 20.8 .38 20.6 .29 22.4 .32 22.8 3 7 22.8 .48 23 .4 .30 23.6 31 24.0 .23 24.5 .26 24.8 .33 25 4 .88 25.7 .99 25.2 l.00 25.8 .46 26. l .37 26 .4 .27 26.9 .23 26.6 .19 34.5 .22 35.0 .21 34.2 13

PAGE 65

w u z <( I:: V) z I-_,II I I I I I I I I 4000 3000 2000 -1 FREQUENCY (cm ) I I ,_ 1000 Figure 25.-The infrared spectra of: (a), Co(DPKH 0) so 4 H O; (b), 2 2 2 Ni(DPKH 2 o) 2 so 4 1/2H 2 0; (c), Cu(DPKH 2 o) 2 so 4 1/2H 2 0; (d) ,[Cu(DPKH 0) (H 0) ]Cl 2H O. 2 2 2 2 2 2 55

PAGE 66

:r: (.9 w 5 56 20 100 t C 0 200 Figure 26.-The TGA Curves for: (a), Cu(DPKH 0) so 4 1/2H O; (b), 2 2 2 Co(DPKH 2 ~) 2 s 4 H 2 0; (c), Ni(DPKH 2 0) 2 so 4 1/2H 2 0.

PAGE 67

Further evidence that the diaquo cation is not present in the sulfate canes from the fact that the complex cobalt sulfate can be treated with sodium carbonate in boiling aqueous solution to produce a crystal] ine material of the composition, Co(DPKOH) 2 1/2H 2 0 whose infrared spectrum shows considerable similarity to the spectrum of the parent sulfate. The region of the infrared spectrum in which sulfate absorbs accounts for much of the difference between the spectra of the ccmplex cobalt sulfate and that of the resulting deprotonated ccmpound. The deprotonated compound certainly does not contain the diaquobis(di-2-pyridylketonehydrate)cobalt(II) cation, nor does the parent sulfate, since both compounds produce comparable infrared spectra. A polymeric structure for the complex sulfates is proposed, as in the case of the comple x nickel(( I) nitrate. However, in the case of the complex sulfates one of the bridging hydroxyl groups appears to have been deprotonated by the sulfate ion which then exists in the sol id as the hydrogen sulfate ion. Treatment with base removes another proton from the complex with the result that the elements of sulfuric acid are eliminated from the complex. The solid-state complex sulfates for which polymeric structures have been proposed produce visible spectra for the individual metals distinct from the spectra of other salts of the same metal and their aqueous solutions. However, the aqueous solution spectra of the complex sulfates are identical to spectra produced by aqueous solutions of the respective metal nitrates or chlorides, indicating that the polymeric structures exist only in the sol id state. 57

PAGE 68

Conductivity data {Figure 27) support the e x istence of dipositive, diaquo species (9, p. 339) in aqueous solutions of the sulfates and indicate that species of condensed structures are present in methanol solutions. The complexes present in methanol solutions exhibit visible spectra distinct from the spectra of the respective solid complex sulfates or their aqueous solutions. Hence another condensed complex sulfate structure exists in methanol solution An indication that a new type of complex is formed in mP.thanol solutions comes from the observation that the complex nickel and copper sulfates require several hours to dissolve in methanol to produce a Sxl03 m solution. The complex cobalt sulfate only partially dissolves in methanol, a color change having occurred in the insoluble portion. Figure 28 shows a model of a possible solid-state complex sulfa~e structure. Only the dipositive, dimeric cation is shown. The anions not shown are hydrogen sulfate ions. Deprotonated Complexes The deprotonated complexes investigated have the following metal to-1 igand ratios as determined by carbon and metal analysis: M:DPK, 3M:4DPK, and M:2DPK. In general, available physical methods short of X-ray crystal structure analysis provide insufficient information to establish with any degree of certainty the structures of these deproton ated complexes. An analogous system is that of simple metal ions in aqueous solution whose deprotonated species indeed exhibit quite complex behavior. 58

PAGE 69

.-.. I C1) 0 E N E u I E .c 0 C1) I) C t1l ,I.J u ::i "O C 0 u IV 0 250" 200 -50 1 b '~ -0----D---. ---<>-----<>() --------'. __ ..._ ___ ___.__ __ __._ __ ___._ ___ __. __ ... __ .01 02 .03 .04 .05 .06 .07 Figurt C 1/2 27.-The molar conductivities in methanol of: (a), Ni(DPKH 0) 2 2 S0 4 1/2H 2 0; {b), Cu{OPKH 2 o) 2 so 4 112H 2 0; and in water; {c), Ni(DPKH 2 o) 2 so 4 t/2H 2 0: {d), Cu{DPKH 2 0) 2 so 4 1/2H 2 0; (e), Co(OP-KH 2 0) 2 s\ H 2 0 59

PAGE 70

60 Figure 28.Two views of [Co(DPKH 2 0)(DP K OH)]~+.

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However, certain statements can be made about the structural naturPs uf these compounJs. Table 3 11sts the specific --1. -1..,VlllfJlt::At::::> prepared and 3Jso includes infrared, equivalent weight, and molecular weight data. The anionic cpmponent of these complexes is either de protonated water (0and/or OH-) or deprotonated di-2-pyridyl ketone 2hydrate (DPKOHand/or DPKO ) Infrared data suggest that deprotonated DFKH O serves the 2 anion function in these complexes. The band near 1400 cm-l referred to in Table 3 is assigned to the 0-H bending vib~ation of the alcohol group (11) and is present in most of the hydrated salt complexes dis-1 cussed earlier. The band near 1400 cm in the salt co~plexes is removed by deuteration and in certain cases by treatment with base. Treatment of the salt complexes with base of course produces the complexes 1 isted in Table 3, and it can be seen in the infrared spectra shown in Figure 29 that none of the deprotonated complexes has a band -1 at 1400 cm of the intensity shown by the spectrum of Co(DPKH 0) SOLH 0. 2 2 I 2 The spectrum of cu 3 (DPK0) 2 (DPKOH) 2 7H 2 0 has a poorly defined band at -1 1400 cm, which is not found in the spectrum of CuDPK07H 2 0 (which should contain no alcohol hydrogen atoms). The infrared spectrum of cu 3 (DPK0) 2 (DPKOH) 2 7H 2 0 (Figure 29b) indicates that two chemical arrangements of deprotonated di-2-pyridyl ketone hydrate are present. I Two bands are present near 1600 cm in the region of the highest energy pyridine band, suggesting that two types of pyridine species are present. On the other hand, the spectrum of -1 CuDPK07H 2 o (Figure 29a) shows only one band near 1600 cm as expected. 61

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Table 3 Deprotonated Complexes Observed Calculated Molecular Formula Equivalent Equivalent Weight Compound IR Spectra Weight Weigh t Weight Co ( DP KOH) 1 /2H 0 Like Co(DPK) 2 so 4 3H 2 0 470 234 235 378 2 2 No band at 1400 -1 cm 11 Co(DPK) 2 5 + All bands broad 524 358 1 /2H 2 0-3H -1 515 175 No band at 1400 cm II I Cu(DPKO) (DPKOH) 7H 0 Band at 1400 cm -1 1120 185 l87 502 re2 2 2 moved by deuteration IV CuDPK07H 2 0 Fewer bands than I I I 390 194 195 _,_ --~ No band at 1400 -1 cm V PdDPK02H 2 0 Similar to IV 327 -;'~ Insoluble in methanol. k; '\ Insoluble in hydrochloric acid. ,/ /

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w u z <( I:: V> z I.111~~t 1~~r1 r l l II ~r n fi 1 Jn\n r ,1 ,, 11 it f 1 r~ ""\ \ l /1 r r I (~I a 4000 3000 2000 -1 FREQUENCY (cm ) l. 11 i \ 1000 Figure 29.-The infrared spectra of:( a ), CuDPK07H 2 0; (b), Cu 3 (DPK0) 2 + (DPKOH) 7H O; (c), Co(DPK) 5 1/2H 0-3H ; (d), Co(DPKOH) 2 2 2 2 2 1/2H 2 0; ( e), Co(DPKH 2 0) 2 SOL/1 2 0.

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A possible structure for cu 3 (DPK0) 2 (DPK0H) 2 7H 2 0 having two distinct types of ligands is shown in Figure 30c. An analogous structure for CuDPK07H 2 0 is shown in Figure 30a. A similar structure lacking the two trans water molecules might be e x pected for PdDPK02H 2 0. However, a structure of the type shown in Figure 306 is also possible, although the infrared spectrum of PdDPK02H 2 0 is not that of the simple hydrated ketone. The equivalent weights of both copper compounds are seen in Table 3 to match closely the calculated values. However, similar agree ment between formula weight and molecular w e ight in methanol is not observed for cu 3 (DPK0) (DPK0H) 7H 0, perhaps because solution in 2 2 2 methanol results in dissociation into neutral fragm e nts in addition to an acid-base reaciion producing m e thoxide ions. Conductivity data (Figure 31) support the existence of ionic sp e cies in methanol. It was pointed out in an earlier discussion that the deprotonated compound Co(DPK0H)l/2H 0 has an infrared spectrum quite similar to that 2 of Co{DPKH 2 o) 2 so 4 H 2 0; both spectra are distinct from the sp e ctra of other neutral and salt complexes. A polymeric structu r e involving bridging hydro x yl groups is probable for Co(DPK0H) 2 1/2H 2 0. But as in the case of the copper compound, the value for its mol e cular w e ight in methanol (378) is less than the formula weight (LOO), indicating that not polymerization but dissociation occurs in meth a nol. Conductivity data indicate that methanol solutions of Co{DPK0H) 2 l/2H 2 0 are electrolytic conductors {Figure 31), as noted for solutions of the copp e r compound Cu {DPK0) {DPK0H) 7H 0. Methanol may react, 3 2 2 2 64

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H 2 0 H 2 0 H ~H H 2 0 H 2 0 H 2 0 H H I .._ __ __ ...... H 2 0 b n a Figure 30.-P 0 ssible structures for: (a), CuDPK07H 2 0; (b), PtDPK02H 2 0 ; (c), cu 3 (DPK0) 2 (DP K OH) 2 7H 2 0. C H

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150 .,,...., I 0 E N E u I E .c 0 u C 100 IO u ::, "C C: 0 u L IO 0 2: 50 .01 .02 03 112 04 C .05 .06 .07 Figure 31.-The molar conductivities in methanol of: (a), Co(DPK) 5 1/2 2 + H 2 0-3H; (6), Co(DPKOH) 2 1/2H 2 0; (c), Cu(DPK0) 2 (DP K OH) 2 66

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donating a proton to the basic complex to form methoxide ions and complex cations. Moreover, dissociation of the unreacted polymeric species into neutral fragments probably occurs in methanol. The complex, Co(DPK) 5 1/2H 0-3H+ is formulated as a Co(I I I) 2 2 compound because of its unusually low magnetic moment (0.96BM) and high apparent equivalent weight (515 vs. 175 calculated). The great majority of Co(I I I) compounds are low spin and diamagnetic, hence a low magnetic moment would be expected. The chemical inertness of Co(l 11) ions quite 1 ikely would prevent protonation of one or more anionic oxygen atoms. Only one anionic oxygen atom of the three required to balance the three positive charges of Co(l 11) in Co(DPK) 2 5 l/2H 2 0-3H+ appears to accept a proton since the observed equivalent weight is equal t o the formu 1 a weight. 67

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SUMMARY It is possible to formulate from the earlier discussion a pattern of behavior for di-2-pyridyl ketone (DPK) as a ligand in aqueous solution based on the following factors: [l] the tendency for hydration of the ketone carbonyl to occur, [2] the steric problem in Pt(I I) and Pd(I I) compounds containing two 1 igand molecules, [3] the tendency to form complexes with Cu(I I), Co(I I), and Ni(I I) in which the number of DPK ligands is two or less, and [4] the acidic nature of the bis(di-2-pyridylketonehydrate)metal(I I) cations. All complexes prepared in aqueous solution contained at least one molecule of the hydrated ketone except [Pt(Pd)DPKC1 2 J. The hydration of the ketone carbonyl appears to be enhanced by coordination to the extent that dehydration of many of the solid hydrates occurred only near or above 100c. Further, hydration of all ketone molecules present occurs unless prevented by steric interactions (as in the case of [CoDPK(DPKH 2 0)Cl ]HO and [Ni(DPK) (NCS) ]2H 0). The related 2 2 2 2 2 reaction of ketal formation occurs in methanol, producing a 1 igand of almost the same nature as the original ketone hydrate. An important facet of the coordination chemistry of di-2-pyridyl ketone is the steric interaction which occurs in complexes containing two molecules of the anhydrous ketone bound in a rigidly planar fashion. Evidence for this interaction was found in the thermal instability of 68

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[Pt(Pd)(DPK) ]Cl relative to [Cu(Co)(DPK) ]Cl The consequences of 2 2 2 2 this steric interaction are, in the case of first row transition metais, that only cis structures are expected for the octahedral complexes of the type [M(DPK) 2 c1 2 ]. A s imilar interaction was not indicated 1n trans-bis(di-2-pyridylketonehydrate)metal(I I) cations because a non planar boat arrangement of the hydrated 1 igands is possible. Most complexes of Ni(II) and bidentate di-imines disproportionate in aqueous solution to form one trisdi-imine cation and one hexaaquo cation. It is therefore unusual that complexes of Ni(II), Cu(II), and Co(I I) containing only two molecules of di-2-pyridyl keton e hydrate are isolated from aqueous solution. Inspection of molecular models of the tris(di-2-pyridylketonehydrate)metal(II) complexes shows that there is considerable steric interaction which is perhaps the reason why no _lris complexes were isolated. Moreover, hydrogen bonding be tween the C-OH oxygen atoms and the trans water hydrogen atoms may occur in the diaquobis(di-2-pyridylketone)metal(I I) complexes to provide additional stabilization. Finally, the acidic nature of bis(di-2-pyridylketonehydrate) metal(I I) complexes terminates the characterization of di-2-pyridyl ketone as a 1 igand. All complexes investigated exhibited acidic behavior as shown by abnormal conductivity behavior and the isolation of de protonated complexes. Cu(I I) formed complexes with metal-to-! igand ratios of 3:4 and I: l. Palladium formed a 1: I complex much 1 ike the Cu(I I) analog. Cobalt yielded two complexes with ratios of 2: 1, one of which appeared to contain Co(I I I). No complexes with either discrete or reproducible metal-to-ligand ratios were isolated for Ni(II).

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A P P E N D I C E S

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Appendix A VISIBLE SPECTRA A common spectrum hawing a maximum near 5600A 0 is observed for aqueous solutions of all the copper salts investigated. In addition, the solid complexes, [Cu(DPKH 2 0) 2 (H 2 o) 2 ]c1 2 2H 2 0 and [Cu(DPKH 2 o) 2 (H 2 o) 2 ] N0 3 ) 2 ,exhibit one band near 5600A 0 in the sol id state. Such a spectrum for Cu(I I) compounds is consistent with a tetragonal structure as evidenced by the spectrum of [Cu(en) (H 2 0) ]+ (en=ethylenediamine) 2 2 (Figure 32a); a known tetragonal complex cation. The anhydrous copper complexes, [Cu(DPK) Cl J and [Cu(DPK) 2 2 2 (N0 3 ) 2 J were assigned els structures on the basis of visible and infrared spectral evidence. The 2,2 1 -dipyridine analog [Ni(Dipy) 2 c1 2 J has been assigned an octahedral structure (12) and the complex cations 2+ 2+ [Cu(Dipy) (H 0) J and [Cu(Phen) (H 0) ] (Phen=l, 10-phenanthrol ine) 2 2 2 2 2 2 have been assigned cis structures in aqueous solution (13). Evidence for the existence of a trans diaquonickel(I I) cation in aqueous and methanol solutions is provided by the fact that the Ni(II) solution spectra of di-2-pyridyl ketone hydrate complexes (Figure 216) match closely the solution spectra of the complex Ni(Sal icylaldehyde) 2 (Figure 326) known by X-ray crystal structure analysis to be trans in the sol id dihydrate(I I) (Jlr). In regular octahedral complexes three absorption bands are expected corresponding to the transitions indicated on the energy level 71

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b a t t +\ I \ i i N t\ I / \ i I l .i : \ I Oimelhyl lormol1', (Al O.G [ f 0 4 "Q ai -~ 802[~ OC 500 700 Waye leogth, m,, Absorption spectra of sohitions containing 0.01 mole of cupric chloride 2nd 0.005, 0 f)l and 0.02 mole of ethylen e diamine per liter. Figure 32.-Reproductions of the visible spectra of: (a), Aqueous solutions containing cupric chloride and ethylenediamine (15); (b), Ni(salicylaldehyde) 2 (16). 72

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diagram shown in Figure 33. The lowest energy transition (d) corresponds to the crystal field splitting parameter, 6, and the transition next highest in energy (c) corresponds to 1.86, while the highest energy transition (a) is a function of the energy difference between the energy states, 3 F and 3 P, of the free ion as well as a function of 6 The spectra of [Ni (DPK) (NO ) ] Ni (DPK) NO 2H 2 O, and Ni (DPK) 2 2 3 2 2 3 (NO 3 ) 2 2H 2 O shown in Figure 21 contain more bands than the spectra of the chloride complexes (Figure 17) and more bands than aqueous solutions of Ni (11) ions. Figure 33 shows an energy level diagram for Ni (11). The three transitions normally observed for octahedral Ni(I I) are indicated; however, a fourth band (b) is sometimes observed and is designated 3A 2 -> 1 E. Perhaps the additional bands in Figure 21 are produced by h . 3A 1 E t 1s trans1t1on, ,.e., 2 -, Table 4 lists spectral assignments for some of the nickel com pounds investigated. 73

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d 8 B = 1080 crn1 for Ni(!() 80 .---.--.---,------,--, C d ----'E 20 30 40 50 A/B d:: *Transitions normally observed for octahedral Ni(II). Figure 33.-The energy level diagram for Ni(I I) in an octahedral field. 74

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Table 4 Spectral Assignments for Some Ni(I I) Compounds+ in the Sol id State T r ansition (cm1 ) Complex 3A23TJ 3A2-, l E [Ni (DPK) 2 c1 2 J 9000 18200 24700 9000 [Ni(DPK) 2 (NCS)]2H 2 0 10900 18500 23500 1 0 300 [NiDPK(DPKH 2 0)C1 2 ]2H 2 0 9090 17500 22700 9)90 [Ni (DPK) 2 (No 3 ) 2 J 10000 18200 -23600 12900" 1 0000 _,_ Ni(DPK) (NO) 3H 0 10500 19300 13200" 10500 2 3 2 2 Ni (DPK) 2 (No 3 ) 2 2H 2 0 10200 15900 12800 23800 1 0200 + The spectra are shown in Figures 17 and 2 l. _,_ "Average value of more than o!le band.

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Appendix B MAGNETIC MOMENTS The magnetic moments for most of the compounds investigat e d are 1 isted in Table 5. All are within the normal octahedral range for the individual metals (Cu(II), l.70-2.20BM; Ni(II), 2.80-3.SOBM; and Co(II), 4.305.20BM, exc e pt the value for Co(DPKH 2 0) SOHO and the value for 2 4 2 + Co(DPK) 2 5 l/2H 2 0-3H Data for Co(DPKH 2 o) 2 so 4 H 2 0 are sho w n in Figures 34 and 35 and Table 6. Such behavior has b e en observed before and a quantitative interpretation has be e n attempted (17). A similar effect has been observed for a strongly tetragonally distorted Cobalt(! I) complex (18),which perhaps indicates that Co(DPKH 0) 2 2 S0 4 H 2 0 is similarly distorted. The magnetic moment observed for Co(DPK) 2 5 l/2H 2 0-3H+ (0.96BM) is far too low for Co(I I) ; hence the compound is assumed to contain Co(I I)) which in most compounds is low spin and therefore diamagnetic. The residual paramag ne tism observed for the above compound is not well understood and requires a thorough investigation. 76

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Table 5 Room Temperature Magnetic Moments Complex Cu(DPK)i1 2 6H 2 0 Cu(DPK) (NO ) 4H 0 2 3 2 2 Ni (DPK) (NO ) 3H 0 2 3 2 2 Ni (DPK) Cl 3H 0 2 2 2 Ni(DPK) Cl 2 2 Co(DPK) Cl 3H 0 2 2 2 Co(DPK) 2 (SCN) H 0 2 2 Ni (DPK) (SCN) 2H 0 2 2 2 Cu(DPK) 2 so 4 2 1/2H 2 0 Co(DPK) l0 4 3H 2 0 Ni(DPK) 2 so 4 2 l/2H 2 0 Co(DPKOH) 2 1/2H 2 0 Co(DPK) 5 1/2H 0-3H+ 2 2 Cu 3 (DPK0) 2 (DPKOH) 2 7H 2 0 CuDPK07H 0 2 *see Table 6 and Figures 34 and 35. /1.. eff l.90 1.83 3. 12 3. lo 3. 16 4. 74 4.97 3.08 1.98 3. 14 4.45 0.96 1.80 J.99 77

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350 ~1x 300 250 200 100 160 220 280 340 400 T ( K 0 ) Figure 34.-The temperature susceptibll ity of Co(DPK) 2 so 4 3H 2 0.

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4.0 3.5 ... C Q) E 0 ::: u ....., 3.0 Q) C O'l (Q ::: 2.5 0 0 0 2.0 150 200 250T (Ko) 300 350 400 Figure 35.-The temperature dependence of the magnetic moment of Co(DPK) 2 so 4 3H 2 0.

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Tabl e 6 Temperature Dependence of the Molar Susceptibility and Magnetic Moment of Co(DPK) 2 so 4 3H 2 0 T, K 0 6 units) eff(Bohr magnetons) -Xe X 10 ( cgs 124.99 4806 2.20 139.35 4529 2.24 152.98 3945 2.20 294.65 3188 2.74 310. 15 3294 2.86 328.59 3759 3. 14 346. 17 4378 3.48 365.55 5044 3.85 382.99 5398 4.07 398.92 5494 4.20 174. 51 3444 2. 19 192.45 3191 2.22 210.31 2972 2.24 230.00 2831 2.28 250.00 2768 2.35 260.00 2768 2.40 270.00 2766 2.45 280.00 2828 2.52 294.65 3002 2.66 80

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Appendix C INFRARED SPECTRA The infrared spectra of [PtDPKCl) and di-2-pyridyl ketone are shown in Figures 36 and 37. The greater number of bands in the spectrum of di-2-pyridyl ketone {Figure 36) sugg e sts that both cis and trans conformations exist in the molten free ligand whereas, as expected, only a cis conformation is present in [PtDPKC1 2 J {Figure 37). 2,2dipyridine, a related molecule, does have a cis conformation in the sol id state (19). Figure 38 shows the infrared spectra of CuDPAC1 2 Cu{DPA) 2 c1 2 [PtDPAC1 2 ], and [Pt{DPA) ]Cl 2H O (DPA=di-2-pyridyl amine). Splitting 2 2 2 of the band corresponding to the Tr -hydrogen out-of-plane bending vibrational mode occurs in both comple x e s containing two ligand mol e cules but does not occur in the comple x es containing only one ligand molecule. This splitting is perhaps a spectral manifestation of the 1 igand distortion discussed earlier 1n connection with the problem of interl igand steric interaction. If this is the case, the structure of the copper comple x Cu{DPA) 2 c1 2 J would be expected, 1 ike the platinum analog, to involve a planar arrangement of the donor nitrogen atoms and a nonplanar boat arrangem e nt of the two 1 igand molecules 81

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r r 1700 :soo 1300 1100 900 FREQUENCY (cm1 ) Figure 36.-The infrared sp~ctrum of di-2-pyridyl ketone (~elt on NaCl mull plates). 700 00 N

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w u z < IV) z II 1700 1500 1300 1100 FREQUENCY (cm-1) Figure 37.-The infrared spectrum (PtDPKC1 2 ] (KBr disc). I ) 900 700 00 \,J

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L1J u z <( tV) z ..... A ......... ,_. d 4000 3000 2000 1000 FREQUENCY ( cmf) Figure 38.-The infrared spectra of: (a) ,[PtDPACl 2 ]; (b}, [Pt(DPA) 2 Jc1 2 2H 2 0; (c), Cu(DPA) 2 cJ 2 ; {d), CuDPACJ 2 84

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Oeuteration of the complex, [Pt(DPKH 2 o) 2 ]cl 2 4H 2 0 produces considera b c ch~nge in its infrared spectrum as is seen in Figur e s 39 and 40. No clear e x planation is readily apparent for the several shifts -1 -1 observed in the region 2000-625 cm In the region 4000-2000 cm more normal behavior is observ e d with one peak being shifted to the 1/ predicted value ( Y hyd rogen=2' 2 Y deuterium) The possibility of exchange of ring hydrogen atoms for deuterium atoms was ruled out by decomposing the deuterated canple x into [PtDPKC1 2 ] and DPK, who i e infrared spectra revealed no abnor m alities. 85

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LLJ u z ct IV) z I1700 1500 1300 1100 FREQUENCY (cm-1) Figure 39.-The infrared spectrum of [Pt(DPKH 2 0) ]Cl 4H 0 (KBr disc). 2 2 2 h 5)00 700

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o-1: UJ u z
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Selected Infrared Spectra Representative infrared spectra of each type of salt complex and each type of deprotonated compound investigated are shown in the following pages. All spect'ra were obtained using KBr discs. The ordinate of each curve is in units of transmittance ( % ), and the abscissa is in units of frequency (cm1 ). 88

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3800 3400 3000 2600 2200 1800 (X) \.0

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1700 1500 Figure 42.-[Cu(DPKH 0) (H 0) ]Cl 2H 0. 2 2 2 2 2 2 I 1300 1100 900 700 \.D 0

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3800 3400 Figure 43.-[NiDPK(DPKH 2 0)Cl ]2H 0. 2 2 3000 2600 2200 1800

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1700 1500 1300 1100 900 700 \.0 N

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3800 3400 Figure 45.-[Ni(DPK) Cl ]. 2 2 3000 2600 2:200 1800

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1700 1500 1300 1100 900 700

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3800 3400 3000 2600 2200 1800 \.0 V,

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1700 1500 Figure 48.Ni (DPKH 0) (NO ) H O. 2 2 3 2 2 1300 1100 900 700

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3800 3400 3000 2600 2200 1800

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1700 1500 1300 1100 900 700 \0 co

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1700 1500 Figure 51.Ni (DPK) (NO ) 2H O. 2 3 2 2 1300 1100 ~100 700 \.0 \.0

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3800 3400 3000 2600 2200 1800 0 0

PAGE 111

1700 1500 1300 1100 900 700 0

PAGE 112

3800 3400 3000 2600 r 2200 1800 0 N

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1 1700 1500 ; 1300 1100 9'.JO 700 0 w

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3800 3400 3000 2600 2200 1800

PAGE 115

1700 1500 1300 1100 900 700 V 0 V,

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3800 3400 3000 2600 noo 1800 Figure 58.Co(DPK0H) 2 1/2H 2 0.

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1700 1500 1300 Figure 59.Co(DPK0H) 2 1/2H 2 0. 1100 5'00 700 0 --.J

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3800 3400 3000 Figure 60.CuDPK07H 2 0. 2600 2200 1800 0 CX>

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1700 1500 1300 Figure 61.CuDPK07H 2 0. 1100 900 700 0 \.D

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3800 3400 3000 2600 noo 1800 0

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, L, 1700 1500 1300 1100 900 700

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BIBLIOGRAPHY 1. W. R. McWhinnie, J. Chem. Soc., 5165 (1964). 2. J. F. Geldard and Francis Lions, J. Am. Chem. Soc., 84, 2262 (1962). 3. T. J. Hurley and M. A. Robinson. In Press. 4. M. Goodgame, J. Chem. Soc., (A)' 63 (1966). 5 R G. Gorild ; "Rec1ctions of Coordln,:1ted Lig a nds and Homogeneous Catalysis; Advances in Chemistry Series # 37,'' American Chemical Society Applied Publ ic.ations, Washington, D.C., 1963, pp. 78-98. 6. E. A. Clevenger, Master's Thesis, University of Florida, 1961. 7. B. N. Figgis and R. S. Nyholm, J. Chem. Soc., 331 (1959). 8. W.W. Brandt, Chem. Rev., 54, 959 (1954). 9. D. A. Macinnes, "The Principles of Electrochemistry," Dover Publications, Inc., New York, N. Y., 1961, p. 339 and pp. 357-8. 10. K. Nakamoto, "Infrar e d Spectra of Inorganic and Coordination Compounds," John Wiley and Sons, Inc., New York, N.Y., 1963, pp. 161 and 173. 11. N. B. Colthup, L. H. Daly, and S. E. Wiberley, "Introduction to Infrared and Raman Spectroscopy," Academic Press, York, N.Y., 1964, p. 2 75. 12. R.H. Lee, Ernest Griswold, and Jacob Kleinberg, lnorg. Chem., l, 1278 ( 1964). 13. C. K. Jorgensen, Acta Chem., Scand., _2, 1362 {1955). 14. J.M. Stewart, E. C. Lingafelter, and J. D. Breaz e ale, Acta Cryst., ~' 888 (1961). 15. H. B. Jonassen and T. H. Dexter, J. Am. Chem. Soc. l.!., 1553 (1949). 16. Gi Ida Maki, J. Chem. Phys., 29, 162 (1958). 17. D. L. Williams, D. W. Smith, and R. C. Stoufer, lnorg. Chem., ., 590 (1967). 18. 0. Ramirez, Ph.D. Dissertation, University of Florida, 1965. 19. F. W. Cagle, Acta Cryst. l, 658 ( 1958). 112

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BIOGRAPHICAL SKETCH F. Wyman Morgan was born January 7, 1941, in Russellville, Alabama. After attending Union Elementary School, he attended Phil Campbell High School and was graduated in May, 1958. In June, 1962, he received the degree of Bachelor of Science from Florence State College, Florence, Alabama. He began his graduate studies September, 1962, at the University of Florida. From that time until August, 1963, he held a graduate assistantship, and from September, 1963, through June, 1965, he held the position of Interim Instructor. From July, 1965, through June, 1967, he held a research assistantship. Mr. Morgan is married to the former Judith Trapp. 113

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This dissertation was prepared under the direction of the chairman of the candidate's supervisory committee and hc:s b ee n app:-oved by all members of that committee. It was submitted to the Dean of the College of Arts and Sciences and to the Graduate Council, and was approved as partial fulfillment of the requirements for the degree of Doctor of Philosophy. August, 1967 _Lll c,.._ Dean, College of Arts and Sciences Dean, Graduate School Supervisory Committee: (7-:. 1 /f : l _..f_ .,I i,. ;_ ;. /" I _..., ., ___ c hai rman l'