Reactions of diphosphine-stabilized Os 3 clusters with triphenylantimony: syntheses and structures of new antimony-containing Os 3 clusters via Sb-Ph bond cleavage.

The reactivity of the trimetallic clusters [Os 3 (CO) 10 (μ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs 3 (CO) 8 {μ 3 -Ph 2 PCH 2 PPh(C 6 H 4 -μ 2 ,σ 1 )}] with triphenylantimony (SbPh 3 ) has been examined. [Os 3 (CO) 10 (μ-dppm)] reacts with SbPh 3 in refluxing toluene to yield three new triosmium clusters [Os 3 (CO) 9 (SbPh 3 )(μ-dppm)] (1), [HOs 3 (CO) 7 (SbPh 3 ){μ 3 -Ph 2 PCH 2 PPh(C 6 H 4 -μ 2 ,σ 1 )}] (2), and [HOs 3 (CO) 7 (SbPh 3 )(μ-C 6 H 4 )(μ-SbPh 2 )(μ-dppm)] (3). [HOs 3 (CO) 8 {μ 3 -Ph 2 PCH 2 PPh(C 6 H 4 -μ 2 ,σ 1 )}] reacts with SbPh 3 (excess) at room temperature to afford [Os 3 (CO) 8 (SbPh 3 )(η 1 -Ph)(μ-SbPh 2 )(μ-dppm)] (4) as the sole product. A series of control experiments have also been conducted to establish the relationship between the different products. The molecular structure of each product has been determined by single-crystal X-ray diffraction analysis, and the bonding in these new clusters has been investigated by electronic structure calculations.