COMPARATIVE-STUDY ON CRYSTAL-STRUCTURES OF [RU(BPY)2(CO)2](PF6)2, [RU(BPY)2(CO)(C(O)OCH3)]B(C6H5)4.CH3CN, AND [RU(BPY)2(CO)(ETA-1-CO2)].3H2O (BPY=2,2'-BIPYRIDYL)

The molecular structures of [Ru(bpy)2(CO)2](PF6)2, [Ru(bpy)2(CO)(C(O)O CH3)]B(C6H5)4.CH3CN as a model complex of [Ru(bpy)2(CO)(C(O)OH)]+, and [Ru(bpy)2(CO)(eta1-CO2)].3H2O have been determined by X-ray analysis. The observation that the Ru-C(O)OCH3 bond distance of[Ru(bpy)2(CO)(C( O)OCH3)]+ is shorter than the Ru-CO2 one of (Ru(bpy)2(CO)(CO2)] sugges ts that the multibond character of the Ru-CO2 bond is not larger than that for Ru-C(O)OCH3. One extra electron pair involved in [Ru(bpy)2(CO )(CO2)] resulting from dissociation of a terminal proton of[Ru(bpy)2(C O)(C(O)OH)]+ may be mainly localized in the CO2 ligand rather than del ocalized over the RuCO2 moiety, and the extended three-dimensional net work of hydrogen bonding between the CO2 ligand and three hydrated wat er molecules compensates the increase in the electron density of the C O2 moiety of [Ru(bpy)2(CO)(CO2)].3H2O.