Sulfido triosmium clusters containing bridging dppm ligand:: crystal structures of [Os3(CO)7(μ3-CO)(μ3-S)(μ-dppm)] and the two isomers of [Os3(CO)7(μ3-S)2(μ-dppm)]

The reaction of [Os-3(CO)(10)(mu-dppm)] (1) with H2S at 110 degreesC leads to the known compound [(mu-H)(2)Os-3(CO)(7)(mu(3)-S)(P-dppm)] (2) (11%) and the new compound [Os-3(CO)(7)(mu(3)-CO)(mu(3)-S)(mu-dppm)] (3) (65%). Treatment of 1 with thiourea at 110degreesC gives 2 (70%). The analogous reaction of 1 with tetramethylthiourea at 110 degreesC yielded two 50 electron stereoisomeric compounds 4a and 4b with stoichiometry [Os-3(CO)(7)(mu(3)-S)(2)(mu-dppm)] in 16 and 64% yields, respectively. The new compounds 3, 4a and 4b were characterized by spectroscopic data and X-ray diffraction studies. Compound 3 reacts with tetramethylthiourea at 110 C to give as and 4b. Hydrogenation of 3 at 1 atmosphere pressure at 151 degreesC gives 2. (C) 2002 Elsevier Science Ltd. All rights reserved.