Chemistry of bridged carboxylate ruthenium complexes. Crystal structures of [Ru(PhCOO)(CO)2(PhCOOH]2, [Ru(4-FC6H4COO)2(CO)5(H2O)]2·0.5 C6H6, and [Ru2(s-BuCO2)2(CO)4(s-BuCO2H)]2