Bimetallic Osmium−Tin Clusters: Addition of Triphenyltinhydride to Unsaturated [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] and Saturated [Os3(CO)10(μ-dppm)]

Reaction of electron-deficient [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] (2) with Ph3SnH at ambient temperature yields the bimetallic osmium−tin dihydride complexes [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(SnPh3)(μ-H)2] (3) and [Os3(CO)8(μ-dppm)(SnPh3)2(μ-H)2] (4) via oxidative-addition of one and two Sn−H bonds, respectively, the latter having SnPh3 ligands bound to adjacent osmium atoms. Cluster 3 converts to 4 via oxidative-addition of a further Sn−H bond followed by reductive-elimination of the orthometalated diphosphine. Heating 4 at 128 °C affords isomeric 5, in which both the SnPh3 ligands are bound to the same metal atom, and 5 is also formed from 2 and excess Ph3SnH at 128 °C. Reaction of [Os3(CO)10(μ-dppm)] (1), the saturated counterpart of 2, with Ph3SnH at 110 °C affords [Os3(CO)9(μ-dppm)(SnPh3)(μ-H)] (6), via oxidative-addition of one Sn−H bond, and this converts to 3 upon further heating via loss of one CO followed by orthometallation of the diphosphine. Treatment of 3 with hydrogen (1 atm) at 110 °C gives both the unsaturated dihydride [Os3(CO)7{μ3-Ph2PCH2P(Ph)C6H4}(SnPh3)(μ-H)2] (7) and the electron-precise trihydride [Os3(CO)8(μ-dppm)(SnPh3)(μ-H)3] (8). Thermolysis of 8 at 110 °C gives 7, while heating 3 in refluxing octane yields, after recrystallization from dichloromethane, the unsaturated cluster [Os3(CO)7{μ3-Ph2PCH2P(Ph)C6H4}(SnPh2Cl)(μ-H)2] (9), whereby the coordinated SnPh3 is transformed into a SnPh2Cl group probably via Sn−Ph bond cleavage and chloride addition to the resulting μ-SnPh2 group. The crystal structures of six of these new osmium−tin clusters have been carried out, allowing a detailed analysis of the relative orientations of metal atoms.