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.