The Potential of N-Heterocyclic Carbene Complexes as Components for Electronically Active Materials

The application of N-heterocyclic carbene complexes as active sites in materials other than catalysis has been remarkably scarce. Inspired by the — often misleading — ‘carbene’ label, which implies a substantial degree of M=C π bonding, we have been interested in evaluating the potential of N-heterocylclic carbene complexes as building blocks for constructing electronically active materials. Electron mobility via the metal-carbon bond has been investigated in monometallic imidazol-2-ylidene complexes and subsequently expanded to polymetallic systems. In particular, ditopic benzobisimidazolium-derived ligands have been explored for the fabrication of bimetallic molecular switches and main-chain conjugated organometallic polymers. Electrochemical analyses have allowed for quantifying the degree of electronic coupling between the metal sites and for identifying the key parameters that govern the intermetallic communication.