Selective aerobic oxidations catalyzed by manganese (III) complexes using redox-active ligands

215 Pages·2011·25.98 MB·English

SELECTIVE AEROBIC OXIDATIONS
CATALYZED BY MANGANESE(III)
COMPLEXES USING
REDOX-ACTIVE LIGANDS

A Thesis
Presented to
The Academic Faculty

by

Clarence J. Rolle III

In Partial Fulfillment
of the Requirements for the Degree
Doctorate in the
School of Chemistry and Biochemistry

Georgia Institute of Technology
December, 2011
SELECTIVE AEROBIC OXIDATIONS
CATALYZED BY MANGANESE(III)
COMPLEXES USING
REDOX-ACTIVE LIGANDS

Approved by:

Dr. Jake D. Soper, Advisor Dr. Angus P. Wilkinson
School of Chemistry and Biochemistry School of Chemistry and Biochemistry
Georgia Institute of Technology Georgia Institute of Technology

Dr. E. Kent Barefield Dr. Christopher W. Jones
School of Chemistry and Biochemistry School of Chemical and Biomolecular
Georgia Institute of Technology Engineering
Georgia Institute of Technology

Dr. Christoph J. Fahrni Date: October 11th, 2011
School of Chemistry and Biochemistry
Georgia Institute of Technology
ACKNOWLEDGEMENTS

I would like to thank Dr. Jake Soper for being a great advisor over the past few years.
His passion for science is inspirational and made my time in lab enjoyable. I would also
like thank my research group members, Aubrey Smith, Michael Bayless and Cameron
Lippert for their encouragement and friendship during my time in graduate school. I
would also like to thank my wife, Hilda Castillo for her emotional support throughout the
course of my studies.
iii
TABLE OF CONTENTS
Page
Acknowledgements iii
List of Tables ix
List of Figures x
List of Symbols and Abbreviations xiii
Summary xvi
Chapter
1. INTRODUCTION 1
1.1. Significance of Oxidation Chemistry 1
1.2. Palladium Catalyzed Selective Oxidations 3
1.3. Selective Aerobic Oxidation by 3d metals 5
1.4. Redox Active Ligands 9
1.5. Thesis Obejective 10
1.6. Works Cited 11
2. REACTIONS OF TETRABROMOCATECHOLATE COMPLEXES WITH
DIOXYGEN 20
2.1. Introduction 20
2.2. Results 21
2.2.1. Preparation and Characterization of MnIII Catecholate
Complexes 21
2.2.2. Reactions of [MnIII(Br cat) ]– with O 28
4 2 2
2.2.3. Catalytic Aerobic Catechol Oxidations 38
2.2.4. Fate of the Reduced O 38
2
2.3. Discussion 41
2.4. Conclusions 43
iv
2.5. Experimental Details 44
2.5.1. General Considerations 44
2.5.2. Methods and Materials 44
2.5.3. Preparation of (nBu N)[MnIII(Br cat) (EtOH)(H O)•EtOH] 45
4 4 2 2
2.5.4. Preparation of (nBu N)[MnIII(Br cat) (Me C=O) ] 46
4 4 2 2 2
2.5.5. Preparation of (nBu N)[MnIII(Br cat) (MeOH)] 46
4 4 2
2.5.6. Preparation of (nBu N)[MnIII(Br cat) (OPPh )] 47
4 4 2 3
2.5.7. Preparation of (PPN)Li [MnIII(Br cat) ] 47
2 4 3
2.5.8. Preparation of hexabromo-2,3-oxanthrenequinone 48
2.5.9. Preparation of (Et NH) [MnIV(Br cat) ] 49
3 2 4 3
2.5.10. Catalytic Aerobic Catechol Oxidation 49
2.5.11. H O detection using TiIVO(SO ) 50
2 2 4
2.5.12. X-Ray Crystallography 51
2.6. Works Cited 55
3. AEROBIC ALCOHOL OXIDATION VIA ALKOXIDE-BRIDGED
MANGANESE(III) DIMERS 61
3.1. Introduction 61
3.2. Results 62
3.2.1. Preparation of Mn(III) Catecholate Complexes 62
3.2.2. Reactions of [MnIII(Br Cat) X]2– with O 76
4 2 2
3.2.3. Catalytic Aerobic Oxidation Reactions with
[MnIII(Br cat) (THF) ]– 79
4 2 2
3.3. Discussion 81
3.3.1. Formation of [MnIII (μ-OCH R) ]4–Dimers 81
2 2 2
3.3.2. Reactions with [MnIII(Br Cat) X]2– with Oxygen 81
4 2
3.3.3. Aerobic Alcohol oxidation catalyzed by [MnIII(Br cat) ]– 82
4 2
3.4. Conclusions 86
v
3.5. Experimental Details 86
3.5.1. General Considerations 86
3.5.2. Methods and Materials 87
3.5.3. Synthesis of (nBu N)[MnIII(Br cat) (THF) ] 88
4 4 2 2
3.5.4. Synthesis of (nBu N) [Na(MeOH) ] [(Br cat) MnIII(μ-
4 2 2 2 4 2
OMe) MnIII(Br cat) ] ([MnIII (μ-OMe) ]4–) 89
2 4 2 2 2
3.5.5. Synthesis of (nBu N) [Na(BnOH) ] [(Br cat) MnIII(μ-
4 2 2 2 4 2
OBn) MnIII(Br cat) ] ([MnIII (μ-OBn) ]4–) 90
2 4 2 2 2
3.5.6. Aerobic Alcohol Oxidations 90
3.5.7. X-Ray Crystallography 91
3.6. Works Cited 96
4. OXIDATIVE COUPLING REACTIONS CATALYZED BY MANGANESE(III)
AMIDOPHENOLATE COMPLEXES 101
4.1. Introduction 101
4.2. Results 104
4.2.1. Preparation and Characterization of Manganese Amidophenolate
Complexes 104
4.2.2. Oxidative Coupling of Grignards 121
4.2.3. Reactions with O 122
2
4.2.4. Scope of Oxidative Coupling Reactions 131
4.3. Discussion 133
4.3.1. Coupling of PhMgBr by MnIIIBr(isq) 133
4.3.2. Reduction of the O 134
2
4.3.3. Advantages of using MnIIIBr(isq) as a catalyst 136
2
4.4. Conclusions 139
4.5. Experimental Detail 139
4.5.1. General Considerations 139
4.5.2. Methods and Materials 140
vi
4.5.3. Synthesis of (Cp* Co)[MnIII(ap )] 141
2 2
4.5.4. Synthesis of MnIIIBr(isq) 141
2
4.5.5. Synthesis of MnIII(OClO )(isq ) 142
3 2
4.5.6. Synthesis of MnIII(Cl)(isq ) 143
2
4.5.7. Synthesis of MnIII(I)(isq ) 143
2
4.5.8. X-Ray Crystallography 144
4.5.9. Catalytic Aerobic Homocoupling Reactions 145
4.6. Works Cited 148
5. REACTIONS OF MANGANESE(III) AMIDOPHENOLATE COMPLEXES
WITH DIOXYGEN 154
5.1. Introduction 154
5.2. Results 155
5.2.1. Attempted Isolation of MnIV(O 2–)(isq) 155
2 2
5.2.2. Preparation and Characterization of Bidentate Manganese
Amidophenolate Complexes. 157
5.2.3. Preparation and Characterization of Tetradentate Manganese
Amidophenolate Complexes 163
5.2.4. Reactions of MnIII(ap)(isq) derivatives with O 168
2
5.2.5. Reactions of [MnIII(L4)]– with O 174
2
5.3. Discussion 176
5.3.1. Synthesis of Mn(III) aminophenol complexes 176
5.3.2. Reactions of MnIII(ap)(isq) derivatives with O 177
2
5.3.3. Reactions of [MnIII(L4)]– with O 178
2
5.4. Conclusions 179
5.5. Experimental Details 179
5.5.1. General Considerations 179
5.5.2. Methods and Materials 180
5.5.3. Synthesis of MnIV(O 2–)(isq) 181
2 2
vii
5.5.4. Synthesis of MnIII(ap )(isq ) 181
tBu tBu
5.5.5. Synthesis of MnIII(phen )(phen ) 182
ap isq
5.5.6. Synthesis of MnIII(ap )(isq ) 182
iPr-Br ipr-Br
5.5.7. Synthesis of PPN[MnIII(L4)] 183
5.5.8. Synthesis of MnIV(L3) 183
2
5.5.9. X-Ray Crystallography 184
5.6. Works Cited 188
6. Future work and conclusions 190
6.1. Conclusions 192
6.2. Future work 194
6.3. Works Cited 195
viii
LIST OF TABLES
Page
Table 2.1: Crystallographic Data and Structure Parameters for
(nBu N)[MnIII(Br Cat) (EtOH)(H O)], (nBu N)[MnIII(Br Cat) (MeOH)],
4 4 2 2 4 4 2
(nBu N)[MnIII(Br Cat) (OPPh )], (nBu N)[MnIII(Br Cat) (Me C=O) )],
4 4 2 3 4 4 2 2 2
(PPN)Li [MnIII(Br cat) ]•5THF, and hexabromo-2,3-oxanthrenequinone.
2 4 3
53
Table 3.1: Selected bond lengths (Å) for series of ([MnIII (μ-OCH R) ]4–) complexes
2 2 2
74
Table 3.2: Crystallographic Data and Structure Parameters for
(nBu N)[MnIII(Br cat) (THF) •THF)],
4 4 2 2
(nBu N) [Na(MeOH) ] [(Br cat) MnIII(μ-OMe) MnIII(Br cat) ]•MeOH,
4 2 2 2 4 2 2 4 2
(nBu N) [Li(MeOH)] [(Br cat) MnIII(μ-OMe) MnIII(Br cat) ]•MeOH.
4 2 2 4 2 2 4 2
(PPN) [Li] [(Cl cat) MnIII(μ-OMe) MnIII(Cl cat) ]•MeOH,
2 2 4 2 2 4 2
(nBu N) [Na] [(Br cat) MnIII(μ-OBn) MnIII(Br cat) ]•BnOH, and
4 1.66 2.33 4 2 2 4 2
(nBu N) [MnIIICl(Br cat) ].
4 2 4 2
94
Table 4.1: Selected bond lengths for MnIII(isq)(ap)•1.25(C H ),MnIII(isq)(ap)(CH CN),
7 8 3
CoCp* [MnIII(ap) ]•2(CH CN). MnIIIBr(isq) •0.42(C H ), and
2 2 3 2 6 14
MnIIIClO (isq) •0.25(CH Cl )0.25(C H ).
4 2 2 2 7 8
119
Table 4.2: Crystallographic Data and Structure Parameters for MnIII(isq)(ap)•1.25(C H ),
7 8
MnIII(ap)(isq)(CH CN), (Cp* Co)[MnIII(ap) ]•2MeCN,
3 2 2
MnIIIBr(isq) •0.42C H and [MnIII(OClO )(isq) ]•0.25CH Cl •0.25C H
2 6 14 3 2 2 2 7 8
146
Table 5.1: Crystallographic Data and Structure Parameters for MnIV(O 2–)(isq) ,
2 2
MnIII(phen )(phen ), (MnIII(ap )(isq ), MnIII(ap )(isq ),
ap isq tBu tBu iPr-Br ipr-Br
PPN[MnIII(L4), and MnIV(L3)
186
ix
LIST OF FIGURES
Page
Figure 1.1: Structures of the active sites of galactose oxidase, catechol oxidase and 6
ascorbate oxidase
Figure 1.2: The multiple oxidation states of redox active ligands 9
Figure 2.1: Solid-state structure of the anion in
(nBu N)[MnIII(Br cat) (EtOH)(H O)•(EtOH)] 23
4 4 2 2
Figure 2.2: Solid-state structure of the anion in (nBu N)[MnIII(Br cat) (Me C=O) ] 25
4 4 2 2 2
Figure 2.3: Solid-state structure of the anion in (nBu N)[MnIII(Br cat) (MeOH)] 27
4 4 2
Figure 2.4: Solid-state structure of the anion in (nBu N)[MnIII(Br cat) (OPPh ] 29
4 4 2 3
Figure 2.5: Complete solid-state structure of hexabromo-2,3-oxanthrenequinone 31
Figure 2.6: Solid-state structures of the anion (PPN)Li [MnIII(Br cat) ]•5THF 34
2 4 3
Figure 2.7: UV–vis spectra for reaction of [MnIII(Br cat) ]3– with 1 atm O 36
4 3 2
Figure 2.8: Selected UV–vis absorption data for the oxidation of 1.0 × 10–3 M 3,5-
tBu catH to 3,5-tBu bq in acetone at 298 K with 1 atm O using 2.1 × 10–6
2 2 2 2
M [(nBu N)[MnIII(Br cat) (Me C=O) ] as a catalyst 40
4 4 2 2 2
Figure 3.1: Solid-state structure of the anion in (nBu N)[MnIII(Br cat) (THF) ]•(THF) 63
4 4 2 2
Figure 3.2: Solid-state structure of the sodium salt of anion in
(nBu N) [Na(MeOH) ] [(Br cat) MnIII(μ-OMe) MnIII(Br cat) ]•MeOH 65
4 2 2 2 4 2 2 4 2
Figure 3.3: Solid-state structure of the sodium salt of anion in
(nBu N) [Na(MeOH) ] [(Br cat) MnIII(μ-OMe) MnIII(Br cat) ]•MeOH 67
4 2 2 2 4 2 2 4 2
Figure 3.4: Solid-state structure of the of the anion in (PPN) [Li] [(Cl cat) MnIII(μ-
2 2 4 2
OMe) MnIII(Cl cat) ]•MeOH 70
2 4 2
Figure 3.5: Solid-state structure of an anion in (nBu N) [Na] [(Br cat) MnIII(μ-
4 1.66 2.33 4 2
OBn) MnIII(Br cat) ]•BnOH 72
2 4 2
x