Nature of C[sbnd]N bond in N-heterocyclic carbene

Abstract

The electronic structure and bonding in five-membered N-heterocyclic carbene (NHC) have been explored by EDA-NOCV analysis, which indicates that the CN bonds in NHC are different from conventional electron sharing covalent bonds. The interaction between the carbene carbon atom and the adjacent nitrogen atoms in NHC can be best represented as one σ-type 3c-2e electron sharing bond and one σ-type 3c-2e donor–acceptor bond. It can be considered equivalent to two localized representations viz., one electron sharing NC σ bond and one donor–acceptor N → C σ bond between the two nitrogen atoms and the carbene carbon atom.