Synthesis, structure, and spectroscopic properties of gold(I)-carbene complexes

A series of gold(I)-carbene complexes of the type [Au(R-2-bimy)L] (R = Et, Me; bimy = benzimidazol-2-ylidene; L = Cl, Br, I, bimy, thiophenolate, phenylacetylide) have been prepared. These carbene complexes are luminous in acetonitrile solution and in the solid state with long lifetimes at room temperature. Multiple emissions have been observed for different R and L. The crystal structure of [Au(Me-2-bimy)Cl] shows a relatively short intermolecular Au-I-Au-I contact of 3.1664(10) Angstrom and an intermolecular ring pi-pi interaction with a ring-ring distance of 3.45 Angstrom. The structure of [Au(Et-2-bimy)Cl], however, shows only intermolecular ring-ring interactions with a distance of 3.53 Angstrom. Crystal structure data suggest that bimy is a high-trans-influence ligand.