Title Page	5
	Copyright Page	6
	Contents	7
	Foreword	11
	Preface	12
	List of Abbreviations and Definitions	14
	Chapter 1 General Introduction	17
	1.1 Definition of Carbenes	17
	1.2 Historical Overview of Carbenes, N-Heterocyclic Carbenes, and Their Complexes	19
	1.2.1 The Quest for Free Stable Carbenes	19
	1.2.2 The Quest for Carbene Complexes	27
	References	31
	Chapter 2 General Properties of Classical NHCs and Their Complexes	33
	2.1 Stabilization in NHCs (Push-Pull Effect)	35
	2.2 Backbone Differences and Their Implications	36
	2.3 Dimerization of Carbenes	38
	2.4 Nomenclature of N-Heterocyclic Carbenes	41
	2.5 Electronic Properties of NHCs and Different Electronic Parameters	45
	2.5.1 Tolman’s Electronic Parameter (TEP) and Related Carbonyl Based Systems	45
	2.5.2 Lever’s Electronic Parameter (LEP)	52
	2.5.3 Huynh’s Electronic Parameter (HEP)	54
	2.6 Steric Properties of NHCs	58
	2.7 Structural Diversity of NHC Ligands and Their Complexes	61
	2.7.1 Donor-Functionalized NHCs	61
	2.7.2 Multidentate NHCs	62
	2.7.3 Pincer-Type NHC Ligands	63
	2.7.4 Tripodal and Macrocyclic Ligands	64
	References	65
	Chapter 3 Synthetic Aspects	68
	3.1 General Routes to Azolium Salts as NHC Precursors	68
	3.1.1 N-Alkylation of Neutral Azoles	68
	3.1.2 Multicomponent Condensation Reactions	71
	3.1.3 Cyclization of Diamines	74
	3.1.4 Cyclization of Formamidines	80
	3.2 General Routes to Free NHCs	82
	3.2.1 NHCs via Deprotonation of Azolium Salts	84
	3.2.2 NHCs via Reduction of Thiones	87
	3.2.3 NHCs via ?-Elimination of Small Molecules	89
	3.3 General Synthetic Routes to NHC Complexes	90
	3.3.1 Coordination of Free NHCs	92
	3.3.2 Cleavage of Electron-Rich Entetramines by Transition Metals	94
	3.3.3 In Situ Deprotonation of Azolium Salts in the Presence of Transition Metals	94
	3.3.4 Carbene Transfer Routes	97
	3.3.5 Oxidative Addition of an Azolium Salt to a Low-Valent Metal Complex	99
	3.3.6 Metal-Template Synthesis Using Isocyanide Complexes as Precursors	101
	3.3.7 NHC Complexes by Small Molecule Elimination	105
	3.3.8 NHC Complexes by Protonation/Alkylation of Azolyl Complexes	109
	References	111
	Chapter 4 Group 10 Metal(0)-NHC Complexes	115
	4.1 Nickel(0)-NHC Complexes	115
	4.1.1 Reactions of Enetetramines and Free NHCs	115
	4.1.2 Reduction of Nickel(II)-NHC Complexes	122
	4.2 Palladium(0)-NHC Complexes	123
	4.2.1 Reactions of Free NHCs	123
	4.2.2 Reduction of Palladium(II)-NHC Complexes	128
	4.3 Platinum(0)-NHC Complexes	131
	4.3.1 Homoleptic Complexes	131
	4.3.2 Heteroleptic Complexes	133
	References	136
	Chapter 5 Group 10 Metal(II)-NHC Complexes	138
	5.1 Nickel(II)-NHC Complexes	138
	5.1.1 Cleavage of Enetetramines and the Free Carbene Route	138
	5.1.2 In Situ Deprotonation of Azolium Salts with Basic Metal Salts	140
	5.1.3 The Silver-Carbene Transfer Route	143
	5.2 Palladium(II)-NHC Complexes	145
	5.2.1 Cleavage of Entetramines and the Free Carbene Route	146
	5.2.2 In Situ Deprotonation of Azolium Salts with External Base	149
	5.2.3 The “Palladium Acetate” Route	151
	5.2.4 The Silver-Carbene Transfer Route	155
	5.2.5 Isomers of Bis(NHC) Palladium(II) Complexes	159
	5.3 Platinum(II)-NHC Complexes	166
	5.3.1 Cleavage of Entetramines	167
	5.3.2 Cyclization of Isocyanide Complexes	168
	5.3.3 The Oxidative Addition Route	169
	5.3.4 The Free Carbene Route	173
	5.3.5 In Situ Deprotonation of Azolium Salts with External Base	175
	5.3.6 In Situ Deprotonation with Basic Platinum Precursors	178
	5.3.7 Carbene Transfer Reactions	180
	References	184
	Chapter 6 Group 11 Metal-NHC Complexes	187
	6.1 Copper(I)-NHC Complexes	187
	6.1.1 The Free Carbene Route	187
	6.1.2 Alkylation of Copper-Azolate Complexes	188
	6.1.3 In Situ Deprotonation with External Base	189
	6.1.4 In Situ Deprotonation with Basic Copper Precursors	193
	6.1.5 The Silver Carbene Transfer Route	196
	6.1.6 The Copper Powder Route	198
	6.2 Silver(I)-NHC Complexes	199
	6.2.1 The Free Carbene Route	199
	6.2.2 In Situ Deprotonation with Basic Silver Precursors	202
	6.2.3 Silver-Carbene Transfer Reactions	208
	6.3 Gold(I)-NHC Complexes	210
	6.3.1 Cleavage of Enetetramines	210
	6.3.2 Protonation/Alkylation of Azolato Complexes	210
	6.3.3 The Free Carbene Route	212
	6.3.4 The Silver-Carbene Transfer Route	216
	6.3.5 Ligand Redistribution and Autoionization of Gold(I) NHC Complexes	226
	6.4 Gold(III)-NHC Complexes	228
	References	234
	Chapter 7 Ruthenium, Rhodium, and Iridium Metal-NHC Complexes	236
	7.1 Ruthenium(II)-NHC Complexes	236
	7.1.1 Cleavage of Enetetramines and the Free Carbene Route	236
	7.1.2 In Situ ?-Elimination	243
	7.1.3 In Situ Deprotonation of Azolium Salts	244
	7.1.4 The Silver-Carbene Transfer Route	246
	7.2 Rhodium(I)- and Rhodium(III)-NHC Complexes	248
	7.2.1 Cleavage of Enetetramines and the Free Carbene Route	248
	7.2.2 In Situ Deprotonation of Azolium Salts	254
	7.2.3 The Silver-Carbene Transfer Route	259
	7.3 Iridium(I)- and Iridium(III) NHC Complexes	261
	7.3.1 Cleavage of Enetetramines and the Free Carbene Route	261
	7.3.2 In Situ ?-Elimination	266
	7.3.3 In Situ Deprotonation of Azolium Salts	267
	7.3.4 The Silver-Carbene Transfer Route	272
	References	277
	Chapter 8 Beyond Classical N-heterocyclic Carbenes I	279
	8.1 N,S-Heterocyclic Carbenes (NSHCs)	279
	8.2 N,O-Heterocyclic Carbenes (NOHCs)	286
	8.3 Expanded Six-Membered NHCs	293
	8.4 Expanded Seven- and Eight-Membered NHCs	298
	8.5 Expanded Diamidocarbenes (DAC)	303
	References	307
	Chapter 9 Beyond Classical N-heterocyclic Carbenes II	309
	9.1 Abnormal Imidazolin-4/5-ylidenes (aNHC)	310
	9.2 Mesoionic 1,2,3-Triazolin-5-ylidenes (MIC)	319
	9.3 Pyrazolin-3/5-ylidenes (Pyry) and Indazolin-3-ylidenes (Indy)	326
	9.3.1 Pyrazolin-3/5-ylidenes	326
	9.3.2 Indazolin-3-ylidenes	333
	9.4 Cyclic (Alkyl)(Amino)Carbenes (CAACs) Or Pyrrolidin-2-ylidenes	336
	9.5 Remote N-Heterocyclic Carbenes (rNHC)	340
	9.5.1 Pyridin-3/4-ylidenes	340
	9.5.2 Pyrazolin-4-ylidenes	342
	References	344
	Index	346
	EULA	351