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Homo and Heterometallic Manganese Clusters

Permanent Link: http://ufdc.ufl.edu/UFE0021614/00001

Material Information

Title: Homo and Heterometallic Manganese Clusters New Metal Architectures, Single-Molecule Magnets, and Physical Phenomena
Physical Description: 1 online resource (254 p.)
Language: english
Creator: Lampropoulos, Christos
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: clusters, magnet, magnetic, magnetism, manganese, material, mn, smm
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Polynuclear discrete clusters incorporating transition metals have been attracting a lot of attention, due to their aesthetically pleasing chemical structures, and their magnetic properties, such as single-molecule magnetism (SMM); this is a property intrinsic to the individual molecules, which makes them capable of functioning as nanoscale magnetic particles. The first species to exhibit such properties was Mn sub12 acetate, which now serves as the ?drosophila? of molecular magnetism. Extension of this chemistry has led to a new high-symmetry Mn sub12 derivative (Mn sub12 tBu) with no intermolecular communication. The thorough investigation of its physical and spectroscopic properties has led to exciting new physics. The use of Mn sub12 clusters as models has allowed for accurate measurement of the magnetization reversal barriers, with the latter finding addressing several misconceptions about SMMs. In the synthesis of clusters, organic groups are often used as ligands, such as oximes, which in this work have been used in Mn chemistry either alone or with azide groups known to be ferromagnetic couplers. The use of methyl two-pyridyl ketone oxime (mpkoH) in combination with azides has afforded a family of half-integer spin hexanuclear SMMs. Extending this work to the bifunctional form of mpkoH, the use of 2,6-diacetylpyridine oxime has provided an entry into new cluster types, including a pentanuclear family of Mn(IV) sub2 Mn(III)MnII sub2 clusters, as well as a Mn(IV) Gd(III)sub2 triangular complex with an unusual combination of metal oxidation states. The thorough study of the latter, using both physical and theoretical methods, allowed for spin-frustration effects to be investigated and understood. Ferromagnetic Mn(III) sub3 triangles have also been important in the recent literature, since some of them behave as SMMs. Thus, a new Mn(III) sub3 triangle was synthesized, from the use of bis(hydroxymethyl)-p-cresol (hmcH sub3), which is ferromagnetically coupled but not a SMM, which is in contrast with other literature examples. The comprehensive magnetostructural correlation between Mn(III) sub3 triangles has led to insights in the structure / property relationship, and to important conclusions about the origin of ferromagnetism and molecular anisotropy. Another ligand used in this work is the non-flexible 1,8-naphthalene dicarboxylate, which has afforded a family of Mn sub13 clusters, resembling the body-centered cubic structure of mineral salts, and the mathematic model of the Archimedian solid, cuboctahedron. A magnetostructural correlation was possible for these Mn sub13 cages, which proved that small ?tweaking? of the structures can affect the magnetic properties, and change the ground states of the molecules. The incorporation of lanthanides could also lead to novel structures, while high oxidation-state clusters could be potentially useful in the chemical industry instead of metal oxides, i.e. in the catalysis of nitric oxides. To replicate these conditions in a molecule a Ce sub6Mn sub4, a Mn sub4 Ce sub2, and a Mn sub8 Ce clusters were synthesized. The Ce(IV) sub6 Mn(III) sub2 Mn(IV) sub2 complex possesses a central Ce(IV) octahedron, capped by two Mn/Ce cubane units, while the Mn4Ce2 cage is a snub octahedron, both unprecedented structural motifs. This work has also afforded the fifth isolated member of a Mn8Ce family of clusters with a saddle-like topology. From the challenging magnetostructural correlation a previously-ignored magnetic pathway was found to dictate the overall spin ground state, and thus the SMM properties.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Christos Lampropoulos.
Thesis: Thesis (Ph.D.)--University of Florida, 2009.
Local: Adviser: Christou, George.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0021614:00001

Permanent Link: http://ufdc.ufl.edu/UFE0021614/00001

Material Information

Title: Homo and Heterometallic Manganese Clusters New Metal Architectures, Single-Molecule Magnets, and Physical Phenomena
Physical Description: 1 online resource (254 p.)
Language: english
Creator: Lampropoulos, Christos
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: clusters, magnet, magnetic, magnetism, manganese, material, mn, smm
Chemistry -- Dissertations, Academic -- UF
Genre: Chemistry thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Polynuclear discrete clusters incorporating transition metals have been attracting a lot of attention, due to their aesthetically pleasing chemical structures, and their magnetic properties, such as single-molecule magnetism (SMM); this is a property intrinsic to the individual molecules, which makes them capable of functioning as nanoscale magnetic particles. The first species to exhibit such properties was Mn sub12 acetate, which now serves as the ?drosophila? of molecular magnetism. Extension of this chemistry has led to a new high-symmetry Mn sub12 derivative (Mn sub12 tBu) with no intermolecular communication. The thorough investigation of its physical and spectroscopic properties has led to exciting new physics. The use of Mn sub12 clusters as models has allowed for accurate measurement of the magnetization reversal barriers, with the latter finding addressing several misconceptions about SMMs. In the synthesis of clusters, organic groups are often used as ligands, such as oximes, which in this work have been used in Mn chemistry either alone or with azide groups known to be ferromagnetic couplers. The use of methyl two-pyridyl ketone oxime (mpkoH) in combination with azides has afforded a family of half-integer spin hexanuclear SMMs. Extending this work to the bifunctional form of mpkoH, the use of 2,6-diacetylpyridine oxime has provided an entry into new cluster types, including a pentanuclear family of Mn(IV) sub2 Mn(III)MnII sub2 clusters, as well as a Mn(IV) Gd(III)sub2 triangular complex with an unusual combination of metal oxidation states. The thorough study of the latter, using both physical and theoretical methods, allowed for spin-frustration effects to be investigated and understood. Ferromagnetic Mn(III) sub3 triangles have also been important in the recent literature, since some of them behave as SMMs. Thus, a new Mn(III) sub3 triangle was synthesized, from the use of bis(hydroxymethyl)-p-cresol (hmcH sub3), which is ferromagnetically coupled but not a SMM, which is in contrast with other literature examples. The comprehensive magnetostructural correlation between Mn(III) sub3 triangles has led to insights in the structure / property relationship, and to important conclusions about the origin of ferromagnetism and molecular anisotropy. Another ligand used in this work is the non-flexible 1,8-naphthalene dicarboxylate, which has afforded a family of Mn sub13 clusters, resembling the body-centered cubic structure of mineral salts, and the mathematic model of the Archimedian solid, cuboctahedron. A magnetostructural correlation was possible for these Mn sub13 cages, which proved that small ?tweaking? of the structures can affect the magnetic properties, and change the ground states of the molecules. The incorporation of lanthanides could also lead to novel structures, while high oxidation-state clusters could be potentially useful in the chemical industry instead of metal oxides, i.e. in the catalysis of nitric oxides. To replicate these conditions in a molecule a Ce sub6Mn sub4, a Mn sub4 Ce sub2, and a Mn sub8 Ce clusters were synthesized. The Ce(IV) sub6 Mn(III) sub2 Mn(IV) sub2 complex possesses a central Ce(IV) octahedron, capped by two Mn/Ce cubane units, while the Mn4Ce2 cage is a snub octahedron, both unprecedented structural motifs. This work has also afforded the fifth isolated member of a Mn8Ce family of clusters with a saddle-like topology. From the challenging magnetostructural correlation a previously-ignored magnetic pathway was found to dictate the overall spin ground state, and thus the SMM properties.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Christos Lampropoulos.
Thesis: Thesis (Ph.D.)--University of Florida, 2009.
Local: Adviser: Christou, George.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-05-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0021614:00001


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5 6 7 8 5 6 7 8 9 10 11 9 10 11

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13 14 13 13 13 13 14 14 14 16 17 18 19 16 18 16 19 16 19 16

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15

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3 U U 3 5 6 10 13 15 16 17 18 3 3 5 8 5 6 7 8 9 10 11 9 10 11 13 14 13 14 16-18

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16 17 18 5 6 7 8 9 10 11 9 10 13 14 16 17 18 16

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T 1 1 y y z z 1 1

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3 3 3 MT 3 3 D g 3 M M 3 3 3 M 3 3 3 3 S 1 3 3 2 3 3 T 3

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2 2 T 3 T 2 5 5 5 6 6 6 7 7 7 8 8 8 5 8 M H T 5 6 M H T 6 M H T 7 8 T 5 6 T 7 8 9 9

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10 10 11 11 11 T 9 T 10 11 9 10 11 9 10 11 13 14 13 M H T 13 MMT T 13 14 MMT T 14 S S> 14 14 J J S S

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16 16 16 17 18 18 16 19 M H T 16 16 MMT T 16 19 16 9 9 13 14 15 15 M H T 15 D vs g M B vs H T 15

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T 15

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p

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p

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Where Nature finishes producing its own species, man begins, using natural things and with the help of this nature, to create an infinity of species.

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T T kT

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T

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T

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T 1 1

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S D S

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trans x y z z S S S S E D D D 1 U S D S U S D 1

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1 1 D

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S N N S N S S N S N N S N S N S N S

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z T

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-1 -0.5 0 0.5 1 -1 -0.5 0 0.5 1 M/Ms 0H (T) 0.004 T/s 1.3 K 1.8 K 2 K 2.2 K 2.4 K 2.6 K 2.8 K 3 K 3.6 K

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2.1 Introduction

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1 1 1 1 1

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yx z z x y x y z x y z 1

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1 1 1 1 1

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1 2 3 1 3 I 4 2 I a S 3 3 3 1 1 3 3 1 1 2 3

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2 2.2 Experimental Secti on 2.2.1 Synthesis 1 4 4 3 3

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2.2.2 X -R ay C rystallography 3 SHELXTL6, I I 4 2.2.3 D C and AC M agnetometry

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2.2.4 High -Frequency Electron Paramagnetic Resonance (HFEPR) Spectroscopy

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2.2.5 55Mn Nuclear Magnetic Resonance (NMR) Spectroscopy 3 T1 T1 T1 2.2.6 Other S tudies

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2.3 Results and D iscussion 2.3.1 Synthesis 1 4 4 4 3 n

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3 2.3.2 Description of S tructure 3 3 I 4 3 4 4 3 S4 vide infra

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c 2.3.3 Magnetochemistry 2.3.3.1 Direct current magnetic susceptibility studies 3 T T

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S S T g M H M/ B H/T N B M/ B H/T D z S g D D g S g D D g D g D g D g D

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D 2.3.3.2 Alternating current magnetic s usceptibility studies 3 M M T M M M MT MT S g MT M 3 M T M 3

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M 3 m m m M m M m m sT s sT sT s sT

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3 2.3.3. 3 Arrhenius plot using AC and DC data M U M M 3 M U k

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U k U k M 3 0 Ueff Ueff 1 3 Ueff 2.3.3.4 Hysteresis studies 3 3

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1 mS S mS D D D g g D 4 D g |D g 2.3.3.5 High -frequency EPR spectroscopy 3

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H S z zz xy i i i x y z B g D B B Sz g

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ms S z z S ssszBsEmD'mBmgBm D B D B gz B z 3 E E ms E ms s sszBEmD'mmgBO ms ms S ms ms g D B D B

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ms g D S Bx DS gB B ms B ms D ms 3 B B gx gy 3

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1 D D D D. D 1 ms D ms S 1 ms ms = 1 ms 1 D ms

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D 1 ms 1 S D 1 D 3 1 ms 3 1 ms 3 ms 1 ms 3 D 1 D D 3 1 D 3

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1 3 1 3 1 3 3 1 1 3 2.3.3.6 Single crystal 55Mn NMR spectroscopy 1

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1 S S S S S 1 T 1 T 1 3 3

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3 Qv qQe S S S Heff = HF + Hd + Hl HF Hd Hl HQ H0 HT = HF + Hd + HQ + H0

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IIm II qQe mHEn n eff n m eQ eq nm qQe

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w xxzw A yy wxx w A yyc 3 3 2

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3

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T 3 M T t MMtM tM M t M T T Tk E C Tb N Nh C Sm Sm E T

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T TT Tk E Tb T bk E E 1 E Sm Sm 1 2 3 T T

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T 2. 4 Recent Evidence for N on -Linear Arrhenius Beh avior in Single -molecule M agnets TB S D T T U kT U

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T 1 U U U U U U MS S U U U T U U T

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3 2 1 S T 3 Ueff T T U U U 3 B z UEPR U U T U U 2 U U U U U

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U U 3 U U T U U U kT U kT T 3 U U U U U U U T 2 U U T S S U

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S U S S U U U U T T T S U

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U U 2. 5 Conclusions 3 S 3 3 1 2 1 2 3 1 2 1 3

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3 S 3 3 3 D

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2 3 U 1 1 z

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1 z y y z z -1 -0.5 0 0.5 1 2 2.5 3 3.5 4 4.5 5 M/Ms 0Hz (T) 0.04 K 0.007 T/s 0.14 T 0.07 T 0 T 0H0.49 T 0.84 T 0.77 T 0.70 T 0.63 T 0.56 T 0.42 T 0.35 T 0.28 T 0.21 Ttr

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1 C 1

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3

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3

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3 z

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MT 3 M 3 0 50100150200250300 15 20 25 30 35 40 45 50 55 0 10 20 30 40 0 2 4 6 8 10 12 14 16 18

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D g 3 M M 3

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3 3 M

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3 3

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3 ms

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3 B

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S 1 3 ms 1 3 1 1 3

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3

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3 3 3 mS mS

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T 3 1/T ln(1/) 25 freq ac data Fit of data n < 600Hz Fit of data > 600Hz 0.140.160.180.200.22 4 6 8 25 freq ac data Arrhenius fit Ueff= 72.0 K Ueff= 81.4 K Ueff= 69.5 K 1/Tln (1/) 25 freq ac data Fit of data > 600 Hz Fit of data < 600 Hz

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2 2 0.140.160.180.200.22 4 6 8 Data v > 600 Hz Fit of Data v > 600 Hz Data v < 600 Hz Fit of Data v < 600 Hz 1/T (K -1 )ln(1/) Ueff= 83.4 K Ueff= 75.6 K 0.140.160.180.200.22 4 6 8 25 freq ac data 1/T (K -1 )ln(1/) U eff

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T 3 T 2 1/T (K-1) ln ( 1/)1/T (K-1) 01= 2.2(6) 10-8s U1= 66(1) K02= 1.9(4) 1010s U2= 96(2) K

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3.1 Introduction

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3.2 Experimental Section 3.2.1 Syntheses Warning: Azide and perchlorate salts are potentially explosive; such compounds should be synthesized and used in small quantities, and treated with utmost care at all times. 3.2.1.1 [Mn6O3(N3)3(mpko)6(H2O)3](ClO4)2 (5)

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. 5 5 5 3.2.1.2 [Mn6O3(N3)5(mpko)6 (H2O)].4H2O (6) 6 6 6

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3.2.1.3 [Mn5O2(OMe)2(N3)3(dapdo)3(py)2].py.MeOH (7) 3 7 7. 3.2.1.4 [Mn5O2(N3)3.5(O2CM e)(dapdo)3(py)2.5](N3)0.5 (8) 8 8 8

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3.2.2 X -R ay C rystallography 5 7 8 6 F SHELXL -97. 5 6 7 8 P 5 6 7 8 5 8

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3.2.2.1 X -ray crystal structure of complex 5 3.2.2.2 X -ray crystal structure of complex 6 6 3.2.2.3 X -ray crystal structure of complex 7 3.2.2.4 X -ray crystal structure of complex 8 8

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3 .2.3 Other studies 3.3 Results and Discussion 3.3.1 Syntheses

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5

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6 5 6 6 5 7 8 7 8 9 7

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8 7 8 8 7 3.3.2 Description of S tructures 5 5 P 6 5 6

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6 6 5 5 6 5 6 5 6 5 6 7 7

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8 8 8 7

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3.3.3 Magnetochemistry 3.3.3.1 Direct current magnetic susceptibility studies M 5-8 T T 5 6 7 8 5 6 T 5 6

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5 6 5 6 7 8 7 7 8 7 8 8 8 8

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8 7 3.3.3.2 Reduced magnetization studies 5 8 D -MNBHT 5 8 H D z H 5 S D g D g M NB D g vide infra 6 5

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J 7 8 S MS 7 8 S 7 8 7 S D g 8 S D g 3.3.3. 3 Alternating current magnetic susceptibility studies 5-8 5

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6 M M M M 5 6 5 6 M M 5 6 g S M g 7 8 7 8 7 M vide supra 8 S

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7 8 MT 7 8 7 8 g S 3.4 Conclusions 5 6 7 8 5 6 7 8 7 8

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5

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5 5 6

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6 6

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7 7

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7 8 8

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8

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5 8 5 6 7 8

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M H T 5 6 D M H T 5 5

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M H T 6 M H T 7 8 D M H T 7 M H T 8

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T 5 6 5 6

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T 7 8

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4.1 Introduction T S D

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9 10

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11 4.2 Experimental Section 4.2.1 Syntheses 1 12 4.2.1.1 [Ce6Mn4O12(O2CMe)10(NO3)4(py)4]py9MeCN ( 9 pyMeCN). Method A. 1 9 Met hod B. 1 9

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4.2.1.2 [Mn8CeO8(O2CCH2But)12(DMF)14].5DMF ( 10.5DMF). 12 10 4.2.1.3 [Ce2Mn4O2(O2CMe)6(NO3)4(hmp)4]H2O 6MeCN ( 11H2O 6MeCN). 11 11 4.2.2 X -R ay C rystallography

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9 10 11 9 P 10 11 9 10 11 9 SHELXTL6, F 10

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11 F 4.2.3 Other S tudies 4.3 Results and D iscussion 4.3.1 Syntheses

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9 10 9 9 1

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9 vide infra 9 10 10

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11 11 9 11

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4.3.2 Description of S tructures 4.3.1 X -ray crystal structure of complex 9 9 9 9 9 11

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9 4.3.2 X -ray crystal structure of complex 10 10 10 P

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10 10 vide infra 10 10 10

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vide infra 4.3.3 X -ray crystal structure of complex 11 11 11 P 11

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9 10 11 S vide infra 9 11 9 4.3.3 Magnetochemistry 4.3.3.1 Direct current magnetic susceptibility studies 9 9

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9 f J 9 9 9 J S S J S S S S S S S S S S S S J 9 p

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J g J g S J g p S 9 J 9 J

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kT T SE T S T S T S p TIP p 10 S 10 g f 10 vide infra 11 11 f d

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f d g J J J 4.3.3.2 Alternating current magnetic susceptibility studies 9

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9 9

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10 10 S S S S 10

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11 11 10 9 10 10

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10 10 P I n P n P n

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4.4 Conclusions 9 10 11 9 11 10

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9 9

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10 10

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11 11

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11 T 9 9 J

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T 10 11 9 10 11

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9 10

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11

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5.1 Introduction

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S J

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J J S bis p bis p

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S etc 5.2 Experimental 5.2.1 Syntheses 5 .2.1.1 [NEt3(CH2Cl)]2[Mn3O(hmcH)3(hmcH2)3] (13) 13 13 13

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5.2.1. 2 [MnGd2O(O2CPh)3(O2CMe)(dapdo)(dapdoH)2] (14) 14 14 14 5.2.2 X -R ay C rystallography 13 14 I 231 F

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13 I I 14 5.2.3 Other S tudies

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5.3 Results and Discussion 5.3.1 Syntheses 13 bis p 14 14 14

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5 .3.2 Description of Structures 13 13 Cc 13 d 14 14

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I 14 5 .3.3 Magnetochemistry 5 .3.3.1 DC magnetic suscept ibility of complex 13 13 T

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T vs T 13 T vs T T vs T J i.e. J 13 T vs T S S S J J J J J H = J J A T S H = J J E S S J SS SS J SS T vs T S E S S

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13 J J g S S 5 .3.3.2 Reduced magnetization study of complex 13 13 D -MN HT D H D H S D g g 5 .3.3.3 AC magnetic susceptibility of complex 13 13 T T T S g S

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13 5 .3.3.4 Magnetostructural correlation between 13 and other oxo -centered MnIII 3 triangles 13 and n 15 13 -13 15 13 13 13 13 13 13 13 S D

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D C S D D 15 15 13 15 15 15 13 13 13 15 13 15 D J J S

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13 15 sine qua non 13 and 15 d-p-d J J J J J J J in

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d-p-d d-p 15 5 .3.3.2 DC Magnetic susceptibility of complex 14 14

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J J C 14 14 > > H J J

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H J J J J 5 .3.3.3 AC Magnetic susceptibility of complex 14 14 S 14 5 .3.3.4 Theoretical analysis of the spin frustration in complex 14 J J 14

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J 14 J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J J 14 J J J J J J J J J J J J J

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J J J J J J J J J J J J J J J J J J J J J J J J J J J 14 J J J J 14 5.4 Conclusions 14

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13 15 15 13 15 ab initio

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bis p

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13

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14

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13 M H T 13 D 0 10 20 30 40 0 2 4 6 8 10 12 M/NBH/T (kG/K)

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MM T T 13 14 02468 10121416 10 15 20 25 30

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183 Figure 5-9. Plot of the in-phase (M) ac magnetic susceptibility as M T vs T in a 3.5 Oe field oscillating at the indicated frequencies for complex 14. 024681012 20 21 22 23 24 25 26 1000 Hz 250 Hz M T (cm 3 mol -1 K)Temperature (K)

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184 Figure 5-10. Depictions of the indicated | ST, SA states, showing (a) the complete frustration of J when J >0 and J <0, and the resultant ST = 17/2 ground state, (b) the intermediate situation, giving the ST = 13/2 ground state of 14, (c) the complete frustration of J and the resultant ST = 3/2 ground state, and (d) the complete frustration of J when J <0 and J <0, and a resultant ST = 11/2 groud state. Gd Gd Gd Gd Mn Mn a b7/27/2 3/2 7/27/2 3/2 | J | >> | J | | 17/2 7 > J > 0, J < 0 | J | ~ | J | | 13/2 5 > J > 0, J < 0 JJ J JJ J Gd Gd Gd Gd Mn Mn c d7/27/2 3/2 7/27/2 3/2 | J | << | J | | 3/2 0 > J > 0, J < 0 | J | >> | J | | 11/2 7 > J < 0, J < 0 JJ J JJ J

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14 J J S S

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6.1 Introduction TB S D S D S D S D

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6.2 Experiment al S ection 6.2.1 Syntheses 6.2.1.1 [Mn13O8(OH)6(ndc)6] (16)

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16 16 6.2.1.2 [Mn13O8(OEt)5(OH)(ndc)6] ( 17) 17 17 6.2.1.3 [Mn13O8(OEt)6(O2CPh)12] ( 18) 18

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18 18 6.2.1.4 [Mn13O8(OMe)6(ndc)6] (19) 19 6.2.2 X -ray C rystallography

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SHELXTL6, 16 I I 17 I

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18 6.2.3 Other S tudies

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6.3 Results and Discussion 6.3.1 Syntheses 16 17 16 1 16 17 16

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19 17 18 16 17 18 18 18 6.3.2 Description of S tructures 16 16 P

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S6 S6 S6

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17 17 P 16 S6 19 17

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18 C2/c 16 17 17 16 17 S6 16 19 16 19 18 18 6.3.3 Structural C omparison of C omple xes 1 6-18 16 18

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16 17 18 18 16 17 16 18 17 16 17 16 17 18 16 17 18

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17 18 16 18 17 18 16 17 18 16 6.4.4 Magnetochemistry 6.3.4.1 DC M agnetic S usceptibility S tudies on C omplexes 1 6-19 M 16-19 T T T 16 18 17 19 T T

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19 S 16-19 M H S MS

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16 19 S 16 S g D D 16 S g D D g D g D 16 17-19 17-19 S 16

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6.3. 4.2 AC M agnetic S usceptibility S tudies of C omplexes 1 6-19 16 19 T T S 16 S g S 17 19 S 18 T S S 18 T 16 g

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16 18 T 17 18 19 16 18 17 19 6.3 4.3 Single -crystal, High -Field EPR S pectroscopy of C omplex 1 6 16 D g g

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g 16 16 S D 16 16 D D D 16 16 D D D

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6.4 Conclusions 16-18 16 17 18 16 S S D 16

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16

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16 16 16 S6

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17 18

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18 16 19 0 50100150200250300 10 15 20 25 30 35 40 45 50 16 17 18 19

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M H T 16 D 16

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MMT T 16-19 16 02468 10121416 14 16 18 20 22 18 17 19 16

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g

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1 2 3 4 5 6 7 8 9 10 11 12 13 14 n 15 16 17 18 19

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N N g 9) 9

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9 J 0.00 cm-1136.95 cm-1365.20 cm-1 ST=5/2 ST=3/2 ST=1/2 684.75 cm-1ST=7/2

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13 13 J J J

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14 14 J J J

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15

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15 J J g M H T 15 S g D J J J

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D vs g M B vs H T 15

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T 15

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3 3 a I 4 a b c V Z T b R w R c d a b c R = Fo Fc Fod wR w Fo Fc w Fo w Fo Fc n p w Fo m p n p p Fo Fc m n 3 a b c 3 b c b c b c c b c b c b b c

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5 8 5 6. 7 8 P a b c I I R Fo Fc Fo wR w F F w F w F ap bp p F F

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5

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6 7

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8

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9 10 11 9 10 11 P P I I R Fo Fc Fo wR w F F w F w F ap bp p F F

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9

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10

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11 13 14 1 3 14 I Cc a b c I I R Fo Fc Fo wR w F F w F w F ap bp p F F

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13 14

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16-18 1 6 17 18 P P a b c I I R Fo Fc Fo wR w F F w F w F ap bp p F F 16

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17 18

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5 6 5 6 7 8 7 8 9 10 11 9 10 11

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9 10 atom BVS Assignment 9 10 13 14 13 1 4 16 17 18 1 6 17 18

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16

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