Interaction between Ru(CO)2(CH3COO)2[PBu3]2 and Ru4(CO)8(CH3COO)4[P(n-Bu)3]2 in solution: synthesis and characterization of [P(n-Bu)3](CO)2Ru(.mu.-OH)(.mu.-CH3COO-O)(.mu.-CH3COOO-O,O')Ru(CO)(CH3COO)[P(n-Bu)3].