Synthesis and structural characterization of a novel dodecaosmium carbonyl cluster [Os12(CO)30] derived from a new μ4-Oxo hexaosmium carbonyl cluster [Os6(CO)16(μ4-O) (μ-OH)2(μ-CO)2]

A novel hexaosmium μ4-oxo cluster, [Os6(CO)16(μ4-O)(μ-OH)2(μ-C O)2], 1, was isolated from the reaction of [Os3(CO)11(NCMe)] and O2 in refluxing octane. Vacuum pyrolysis of 1 afforded a new highest nuclearity neutral binary osmium cluster, [Os12(CO)30], 2, in moderate yield. Both clusters were fully characterized by both spectroscopic and crystallograpic techniques. Molecular orbital calculations were performed on 1, which was two electrons in excess according to the effective atomic number rule. The redox properties of 1 were investigated by means of cyclic voltammetry and controlled potential coulometry.