Synthesis and structure of tetraosmium hexadecacarbonyl, a metal carbonyl analog of cyclobutane

The authors have recently described the synthesis of Os/sub 4/(CO)/sub 15/ (from Os/sub 3/(CO)/sub 10/(C/sub 8/H/sub 14/)/sub 2/ and Os(CO)/sub 5/) along with the determination of its structure. This was believed to be the first report of a tetranuclear binary carbonyl of osmium. At that time they remarked that, given the stability of Os/sub 3/(CO)/sub 12/, one might expect Os/sub 4/(CO)/sub 16/ would be stable. They now find that this intriguing cluster can be readily prepared from Os/sub 4/(CO)/sub 15/ but that, contrary to arguments based on simple bonding theory, the cluster is not particularly stable.