Read more
Informationen zum Autor HAN VINH HUYNH Department of Chemistry, National University of Singapore, Republic of Singapore Klappentext The Organometallic Chemistry of N-heterocyclic Carbenes describes various aspects of N-heterocyclic Carbenes (NHCs) and their transition metal complexes at an entry level suitable for advanced undergraduate students and above. The book begins with a historical overview of the quest for carbenes and their complexes. Subsequently, the unique properties, reactivities, and nomenclature of the four classical NHCs (derived from imidazoline, imidazole, benzimidazole, and 1,2,4-triazole) are elaborated. General and historically relevant synthetic aspects for NHCs, their precursors, and complexes are then explained. The book continues with coverage of the preparation and characteristics of selected NHC complexes containing the most common metals used in this area: Ni, Pd, Pt, Ag, Cu, Au, Ru, Rh, and Ir. The book concludes with an overview and perspective on the development of various other NHCs beyond the four classical types. Topics covered include: Stabilization, dimerization, and decomposition of NHCs Stereoelectronic properties of NHCs and their evaluation Diversity of NHCs Isomers of NHC complexes and their identication NMR spectroscopic signatures of NHC complexes Normal, abnormal, and mesoionic NHCs The Organometallic Chemistry of N-heterocyclic Carbenes is an essential resource for all students and researchers interested in this increasingly important and popular eld. Zusammenfassung The Organometallic Chemistry of N-heterocyclic Carbenes describes various aspects of N-heterocyclic Carbenes (NHCs) and their transition metal complexes at an entry level suitable for advanced undergraduate students and above. The book starts with a historical overview on the quest for carbenes and their complexes. Inhaltsverzeichnis Foreword ix Preface x List of Abbreviations and Definitions xii 1 General Introduction 1 1.1 Definition of Carbenes 1 1.2 Historical Overview of Carbenes, N¿Heterocyclic Carbenes, and Their Complexes 3 1.2.1 The Quest for Free Stable Carbenes 3 1.2.2 The Quest for Carbene Complexes 11 References 15 2 General Properties of Classical NHCs and Their Complexes 17 2.1 Stabilization in NHCs (Push¿Pull Effect) 19 2.2 Backbone Differences and Their Implications 20 2.3 Dimerization of Carbenes 22 2.4 Nomenclature of N¿Heterocyclic Carbenes 25 2.5 Electronic Properties of NHCs and Different Electronic Parameters 29 2.5.1 Tolman's Electronic Parameter (TEP) and Related Carbonyl Based Systems 29 2.5.2 Lever's Electronic Parameter (LEP) 36 2.5.3 Huynh's Electronic Parameter (HEP) 38 2.6 Steric Properties of NHCs 42 2.7 Structural Diversity of NHC Ligands and Their Complexes 45 2.7.1 Donor¿Functionalized NHCs 45 2.7.2 Multidentate NHCs 46 2.7.3 Pincer¿Type NHC Ligands 47 2.7.4 Tripodal and Macrocyclic Ligands 48 References 49 3 Synthetic Aspects 52 3.1 General Routes to Azolium Salts as NHC Precursors 52 3.1.1 N¿Alkylation of Neutral Azoles 52 3.1.2 Multicomponent Condensation Reactions 55 3.1.3 Cyclization of Diamines 58 3.1.4 Cyclization of Formamidines 64 3.2 General Routes to Free NHCs 66 3.2.1 NHCs via Deprotonation of Azolium Salts 68 3.2.2 NHCs via Reduction of Thiones 71 3.2.3 NHCs via ¿¿Elimination of Small Molecules 73 3.3 General Synthetic Routes to NHC Complexes 74 3.3.1 Coordination of Free NHCs 76 3.3.2 Cleavage of Electron¿Rich Entetramines by Transition Metals 78 3.3.3 In Situ Deprotonation of Azolium Salts in the Presence of Transition Metals 78 3.3.4 Carbene Transfer Routes 81 3.3.5 Oxidative ...
