Synthesis of monodentate bis(N-heterocyclic carbene) complexes of iridium: Mixed complexes of abnormal NHCs, normal NHCs, and triazole NHCs

A stepwise synthesis of mixed monodentate bis-NHC complexes of Ir(I), employing Ag(I)NHC complexes as transfer agents, yields complexes with two monodentate NHCs having different steric and electronic characteristics. The crystal structure of the mixed complex (5) with both a triazole-derived NHC ligand and an imidazole-derived NHC ligand is reported and both the NHC ring geometry and the M–NHC bond lengths are similar to related complexes. The complexes maintain their integrity over time and do not disproportionate, consistent with the NHC ligands not being labile.