Osmium clusters bonding analysis

An interesting oxycarbonyl cluster has been isolated in the reaction of 0s04 with CO under pressure. This was an intermediate in the preparation of the Os3(CO)i2. The X-ray analysis has established this as a cubane structure, with an oxygen bridging the four faces of the osmium tetrahedron. The Os-Os distance is 3.20 A and implies no bonding between the osmium centers. This molecule is of obvious interest as a potential model in the studies of carbon monoxide interaction with metal oxides and also metal surfaces, when the formation of metal oxides occurs (200). 

This oxidative reaction with the oxide surface has been observed even when the triosmium clusters are first bound to anchored ligands, such as PPh2 (0112)2 SIL or 118(0112)3 SIL. Analysis of the osmium L(III) edge EXAFS of the product of Os (00) j 2 with the latter functionalised oxide was entirely in accord with the structure Os H (00) j q(M-S(CH2) 3SIL) with Os-Os bond lengths of 2.848. On thermal decomposition at 48 h, a new component was... 

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