It was only in the early 1990s that carbenes with the carbene carbon being incorporated in a nitrogen containing heterocycle (N-heterocyclic carbenes or NHCs) were found to be stable enough to be isolated. Since the first report on the application of NHCs as ligands in transition metal catalysis in 1995, NHC have found numerous applications and have been established as a versatile and indispensable class of ligands. For many reactions like metathesis or cross-coupling reactions NHCs have often become the ligands of choice, allowing otherwise difficult transformations. In this book leading...