Some aspects of the Lewis base and ligand behavior of N-heterocyclic carbenes

The present article is primarily an overview of recent work from the authorʹs laboratory on the chemistry of stable N-heterocyclic carbenes. The first section deals with complexes of stable N-heterocyclic carbenes with phosphinidenes and arsenidenes, the focal points being preparative methods, molecular structures, electronic structures, and patterns of reactivity. The second section is devoted to complexes of stable N-heterocyclic carbenes with d-block metallocenes. Two general approaches have been taken to the preparation of such complexes, namely the direct reaction of stable N-heterocyclic carbenes with metallocenes and the reaction of metallocenes with imidazolium chlorides. The molecular structures of several representative complexes have been determined by X-ray crystallography.