Synthesis and Reductive Electropolymerization of Metal Complexes with 5,5′-Divinyl-2,2′-Bipyridine

Abstract

Eight transition-metal complexes with 5,5′-divinyl-2,2′-bipyridine (5,5′-dvbpy) or 4,4′-divinyl-2,2′-bipyridine (4,4′-dvbpy) have been synthesized and studied. The ruthenium complexes [Ru(5,5′-dvbpy)(bpy)2]2+, [Ru(5,5′-dvbpy)(4,4′-dpbpy)2]2+, and [Ru(5,5′-dvbpy)(5,5′-dpbpy)2]2+ (bpy = 2,2′-bipyridine; dpbpy = diphenyl-2,2′-bipyridine) with one 5,5′-dvbpy ligand have been successfully deposited on electrode surfaces by reductive electropolymerization. The resulting films are stable and adherent and show well-defined redox processes. In contrast, the complex [Ru(4,4′-dvbpy)(bpy)2]2+ does not polymerize under the same conditions. Complexes [Ru(5,5′-dvbpy)2(bpy)]2+ and [Ru(5,5′-dvbpy)3]2+ with two or three 5,5′-dvbpy ligands have been polymerized as well. As a result of increasing degrees of entanglement, the resulting polymeric films show larger charge-trapping currents and smaller apparent diffusion constants than films of [Ru(5,5′-dvbpy)(bpy)2]2+. The electrochemical properties of the iridium complex [Ir(5...