Reactions of diphosphine-stabilized Os3 clusters with triphenylantimony: syntheses and structures of new antimony-containing Os3 clusters via Sb-Ph bond cleavage.

The reactivity of the trimetallic clusters [Os3(CO)10(µ-dppm)] [dppm = bis(diphenylphosphino)methane] and [HOs3(CO)8{µ3-Ph2PCH2PPh(C6H4-µ2,σ1)}] with triphenylantimony (SbPh3) has been examined. [Os3(CO)10(µ-dppm)] reacts with SbPh3 in refluxing toluene to yield three new triosmium clusters [Os3(CO)9(SbPh3)(µ-dppm)] (1), [HOs3(CO)7(SbPh3){µ3-Ph2PCH2PPh(C6H4-µ2,σ1)}] (2), and [HOs3(CO)7(SbPh3)(µ-C6H4)(µ-SbPh2)(µ-dppm)] (3). [HOs3(CO)8{µ3-Ph2PCH2PPh(C6H4-µ2,σ1)}] reacts with SbPh3 (excess) at room temperature to afford [Os3(CO)8(SbPh3)(η1-Ph)(µ-SbPh2)(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.