Complexes bearing protic N-heterocyclic carbenes: Synthesis and applications

Jahnke M. C., Hahn F. E.

Abstract

Next to complexes bearing N,N'-dialkylazolium-derived Nheterocyclic carbenes (NR,NR-NHCs), the coordination chemistry of protic NHC ligands (NH,NR-NHCs and NH,NH-NHCs) has recently attracted attention. The protic NHC ligands offer multiple opportunities for postsynthetic modifications. This review summarizes methods for the generation of complexes with protic NHC ligands, with a special focus on the recently developed oxidative addition of 2-halogenoazoles to low-valent transition metals. Selected applications for complexes with protic NHC ligands, like the template-controlled preparation of NHC-containing macrocycles and the utilization of the NH function of protic carbene ligands as a molecular recognition unit, will also be discussed.