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 [Os-3(CO)(8){mu(3)-Ph2PCH2P(Ph)C6H4}(mu-H)] (2) with Ph3SnH at ambient temperature yields the bimetallic osmium-tin dihydride complexes [Os-3(CO)(8){mu(3)-Ph2PCH2P(Ph)C6H4}(SnPh3)(mu-H)(2)] (3) and [Os-3(CO)(8)(mu-dppm)(SnPh3)(2)(mu-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 degrees 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 degrees C. Reaction of [Os-3(CO)(10)(mu-dppm)] (1), the saturated counterpart of 2, with Ph3SnH at 110 degrees C affords [Os-3(CO)(9)(mu-dppm)(SnPh3)(mu-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 degrees C gives both the unsaturated dihydride [Os-3(CO)(7){mu(3)-Ph2PCH2P(Ph)C6H4}(SnPh3)(mu-H)(2)] (7) and the electron-precise trihydride [Os-3(CO)(8)(mu-dppm)(SnPh3)(mu-H)(3)] (8). Thermolysis of 8 at 110 degrees C gives 7, while heating 3 in refluxing octane yields, after recrystallization from dichloromethane, the unsaturated cluster [Os-3(CO)(7){mu(3)-Ph2PCH2P(Ph)C6H4}(SnPh2Cl)(M-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 mu-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.