THE ORGANOMETALLIC CHEMISTRY OF THE TRANSITION METALS Second Edition ROBERT H. CRABTREE Yale University New Haven, Connecticut A Wiley-Interscience Publication JOHN WILEY & SONS New York / Chichester / Brisbane / Toronto / Singapore
CONTENTS List of Abbreviations 1 Introduction 1 1.1 Werner Complexes / 1 1.2 The Trans Effect / 6 1.3 Soft versus Hard Ligands / 7 1.4 The Crystal Field / 8 1.5 The Ligand Field / 11 1.6 Back Bonding / 13 1.7 Electroneutrality / 17 1.8 Types of Ligand / 18 References / 22 Problems / 22 2 GENERAL PROPERTIES OF ORGANOMETALLIC COMPLEXES 24 2.1 The 18-Electron Rule / 25 2.2 Limitations of the 18-Electron Rule / 31 2.3 Electron Counting in Reactions / 32 2.4 Oxidation State / 34 2.5 Coordination Number and Geometry / 36 2.6 Effects of Complexation / 38 xv ix
X CONTENTS 2.7 Different Metals / 40 References / 42 Problems / 42 3 METAL ALKYLS, ARYLS, AND HYDRIDES AND RELATED a-bonded LIGANDS 44 3.1 The Stability of Transition Metal Alkyls and Aryls / 44 3.2 The Preparation of Metal Alkyls / 50 3.3 Characterization and Properties of Metal Alkyls / 53 3.4 Related cr-bonded Ligands / 57 3.5 Metal Hydride Complexes / 60 3.6 Bond Strengths for Classical cr-bonding Ligands / 66 References / 69 Problems / 70 4 CARBONYLS, PHOSPHINE COMPLEXES, AND LIGAND SUBSTITUTION REACTIONS 72 4.1 Metal Complexes of CO, RNC, CS, and NO / 72 4.2 Phosphines as Ligands / 83 4.3 Dissociative Substitution / 86 4.4 The Associative Mechanism / 89 4.5 Redox Effects, The I Mechanism, and Rearrangements in Substitution / 92 4.6 Photochemical Substitution / 96 4.7 Steric and Solvent Effects in Substitution / 98 References / 102 Problems / 104 5 COMPLEXES OF TT-BOUND LIGANDS 106 5.1 Alkene and Alkyne Complexes / 106 5.2 Allyl Complexes / 112 5.3 Diene Complexes / 117 5.4 Cyclopentadienyl Complexes / 121 5.5 Complexes of Arenes and Other Alicyclic Ligands / 129 5.6 Metalacycles and Isoelectronic and Isolobal Replacement / 132 5.7 Stability of Polyene and Polyenyl Complexes / 134 References / 136 Problems / 138
CONTENTS Xi 6 OXIDATIVE ADDITION AND REDUCTIVE ELIMINATION 140 6.1 Three-Center Additions / 143 6.2 S N 2 Reactions / 146 6.3 Radical Mechanisms / 147 6.4 Ionic Mechanisms / 149 6.5 Reductive Elimination / 151 6.6 Oxidative Coupling and Reductive Cleavage / 155 References / 158 Problems / 159 7 INSERTION AND ELIMINATION 161 7.1 Reactions Involving CO / 163 7.2 Insertions Involving Alkenes / 168 7.3 Other Insertions / 173 7.4 a, ß, 7, and 8 Elimination / 174 References / 178 Problems / 180 8 NUCLEOPHILIC AND ELECTROPHILIC ADDITION AND ABSTRACTION 183 8.1 Nucleophilic Addition to CO / 186 8.2 Nucleophilic Addition to Polyene and Polyenyl Ligands / 188 8.3 Nucleophilic Abstraction in Hydrides, Alkyls, and Acyls / 196 8.4 Electrophilic Addition to the Metal / 197 8.5 Electrophilic Abstraction of Alkyl Groups / 197 8.6 Single-Electron Transfer Pathways / 200 8.7 Reactions of Organic Free Radicals with Metal Complexes / 201 References / 202 Problems / 203 9 HOMOGENEOUS CATALYSIS 206 9.1 Alkene Isomerization / 210 9.2 Alkene Hydrogenation / 212 9.3 Alkene Hydroformylation / 223 9.4 The Hydrocyanation of Butadiene / 226
XÜ CONTENTS 9.5 Alkene Hydrosilation and Hydroboration / 229 References / 232, Problems / 234 10 CHARACTERIZATION OF ORGANOMETALLIC COMPOUNDS 236 10.1 Isolation / 236 10.2 'H NMR Spectroscopy / 237 10.3,3 C NMR Spectroscopy / 242 10.4 31 P NMR Spectroscopy / 243 10.5 Dynamic NMR / 245 10.6 Spin Saturation Transfer / 250 10.7 T { and NOE / 251 10.8 Isotopic Perturbation of Resonance / 256 10.9 IR Spectroscopy / 258 10.10 Crystallography / 261 10.11 Other Methods / 263 References / 266 Problems / 268 11 CARBENES, METATHESIS, AND POLYMERIZATION 270 11.1 Metal Carbenes / 274 11.2 Metal Carbynes / 286 11.3 Bridging Carbenes and Carbynes / 288 11.4 Alkyne Metathesis / 291 11.5 Alkene Polymerization and Oligomerization / 294 11.6 Multiple Bonds to Heteroatoms / 302 References / 306 Problems / 309 12 THE ACTIVATION OF SMALL MOLECULES 311 12.1 CO Activation / 311 12.2 C0 2 Activation / 318 12.3 Alkane Activation / 321 References / 330 Problems / 332 13 CLUSTERS AND THE METAL-METAL BOND 335 13.1 Structures / 336 13.2 The Isolobal Analogy / 348
CONTENTS XÜi 13.3 Synthesis / 353 13.4 Reactions / 355 13.5 Giant Clusters / 363 References / 366 Problems / 367 14 APPLICATIONS TO ORGANIC SYNTHESIS 370 14.1 Metal Alkyls and Hydrides / 370 14.2 Reduction,Oxidation,andControlof Stereochemistry / 382 14.3 Protection and Deprotection / 386 14.4 Reductive Elimination / 390 14.5 Coupling Reactions / 391 14.6 Insertion Reactions / 396 14.7 Nucleophilic Attack on a Ligand / 398 14.8 Carbene Reactions / 407 References / 408 Problems / 410 15 OXIDATION AND HIGH-OXIDATION-STATE COMPLEXES 413 15.1 Polyalkyls / 415 15.2 Polyhydrides / 420 15.3 Cyclopentadienyl Complexes / 422 15.4 Alkyne Complexes / 424 References / 426 Problems / 427 16 BIOORGANOMETALLIC CHEMISTRY 428 16.1 Introduction / 428 16.2 Coenzyme B l2 / 434 16.3 Nitrogen Fixation / 440 16.4 The Nickel Enzymes / 446 References / 454 Problems / 455 USEFUL TEXTS ON ALLIED TOPICS 457 MAJOR REACTION TYPES 460 SOLUTIONS TO PROBLEMS 462 INDEX 477