Stable cyclic carbenes and related species beyond diaminocarbenes

Abstract

A big family: Neutral carbon-based ligands are not restricted to classical cyclic diaminocarbenes (NHCs). Several other types of cyclic carbenes are stable and act as strong electron donors (see picture). Cyclic bent allenes (CBAs), carbodiphosphoranes (CCDPs), and vinylidenephosphorane (CVP) can even behave as four-electron donors. The gamut of electronic and steric properties available makes carbon ligands strong competitors to the phosphorus family. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.