Hypercarbon Chemistry

GEORGE A. OLAH, PhD, is the 1994 Nobel Laureate in Chemistry, Founding Director of the Loker Hydrocarbon Research Institute, and Distinguished Loker Chair Professor at the University of Southern California. A pioneer in the hypercarbon chemistry field, Dr. Olah has published numerous papers, books, and monographs. G. K. SURYA PRAKASH, PhD, is the George A. and Judith A. Olah Nobel Laureate Chair Professor and the Director of the Loker Hydrocarbon Research Institute at the University of Southern California. KENNETH WADE, PhD, DSc, FRS, is an Emeritus Professor at the University of Durham, UK and a Senior Fellow of the Loker Hydrocarbon Research Institute at the University of Southern California. ÁRPÁD MOLNÁR, DSc, is an Emeritus Professor at the University of Szeged, Hungary, and a Senior Fellow of the Loker Hydrocarbon Research Institute at the University of Southern California. ROBERT E. WILLIAMS, PhD, is a Senior Fellow of the Loker Hydrocarbon Research Institute at the University of Southern California.

Foreword to the First Edition xiii Preface to the Second Edition xv

Preface to the First Edition xvii

1. Introduction: General Aspects 1

1.1. Aims and Objectives 1

1.2. Some Definitions 2

1.3. Structures of Some Typical Hypercarbon Systems 5

1.4. The Three-Center Bond Concept: Types of Three-Center Bonds 10

1.5. The Bonding in More Highly Delocalized Systems 21

1.6. Reactions Involving Hypercarbon Intermediates 26

References 31

2. Carbon-Bridged (Associated) Metal Alkyls 37

2.1. Introduction 37

2.2. Bridged Organoaluminum Compounds 41

2.3. Beryllium and Magnesium Compounds 50

2.4. Organolithium Compounds 53

2.5. Organocopper, Silver, and Gold Compounds 58

2.6. Scandium, Yttrium, and Lanthanide Compounds 62

2.7. Titanium, Zirconium, and Hafnium Compounds 64

2.8. Manganese Compounds 66

2.9. Other Metal Compounds with Bridging Alkyl Groups 68

2.10. Agostic Systems Containing Carbon–Hydrogen–Metal 3c–2e Bonds 70

2.11. Conclusions 76

References 77

3. Carboranes and Metallacarboranes 85

3.1. Introduction 85

3.2. Carborane Structures and Skeletal Electron Numbers 87

3.4. MO Treatments of Closo Boranes and Carboranes 104

3.5. The Bonding in Nido and Arachno Carboranes 107

3.6. Methods of Synthesis and Interconversion Reactions 111

3.7. Some Carbon-Derivatized Carboranes 114

3.8. Boron-Derivatized Carboranes: Weakly Basic Anions [CB11H6X6]− 122

3.9. Metallacarboranes 123

3.10. Supraicosahedral Carborane Systems 133

3.11. Conclusions 137

References 137

4. Mixed Metal–Carbon Clusters and Metal Carbides 149

4.1. Introduction 149

4.2. Complexes of CnHn Ring Systems with a Metal Atom: Nido-Shaped MCn Clusters 150

4.3. Metal Complexes of Acyclic Unsaturated Ligands, CnHn+2 157

4.4. Complexes of Unsaturated Organic Ligands with Two or More Metal Atoms: Mixed Metal–Carbon Clusters 160

4.5. Metal Clusters Incorporating Core Hypercarbon Atoms 162

4.6. Bulk Metal Carbides 173

4.7. Metallated Carbocations 176

4.8. Conclusions 176

References 177

5. Hypercoordinate Carbocations and Their Borane Analogs 185

5.1. General Concept of Carbocations: Carbenium Versus Carbonium Ions 185

5.2. Methods of Generating Hypercoordinate Carbocations 188

5.3. Methods Used to Study Hypercoordinate Carbocations 189

5.4. Methonium Ion (CH5 +) and Its Analogs 195

5.5. Homoaromatic Cations 247

5.6. Hypercoordinate (Nonclassical) Pyramidal Carbocations 260

5.7. Hypercoordinate Heterocations 266

5.8. Carbocation–Borane Analogs 268

5.9. Conclusions 276

References 277

6. Reactions Involving Hypercarbon Intermediates 295

6.1. Introduction 295

6.2. Reactions of Electrophiles with C–H and C–C Single Bonds 298

6.3. Electrophilic Reactions of π-Donor Systems 383

6.4. Bridging Hypercoordinate Species with Donor Atom Participation 388

6.5. Conclusions 394

References 394

Conclusions and Outlook 417

Index 419