Over the past four decades tris(diimine)Ru(II) complexes, particularly [Ru(bpy)3]2+, have attracted much attention as they can be used as potential solar energy converters and as effective sensitizers in the photolysis of water and the influence of diimine ligands have been examined. As many biological electron-transfer systems are based on copper and iron coordinated mainly to sulfur donor sites, we have investigated the effect of incorporating these donors on spectral and electrochemical prop ...