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.