A comparative study of the reactivity of unsaturated triosmium clusters [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] and [Os3(CO)9{μ3-η2-C7H3(2-Me)NS}-(μ-H)] with tBuNC

Treatment of unsaturated [Os-3(CO)(8){mu(3)-Ph2PCH2P(Ph)C6H4}(mu-H)] (2) with (BuNC)-Bu-t at room temperature gives [Os-3(CO)(8)(CNBut)){mu(3)-Ph2PCH2P(Ph)C6H4}(mu-H)] (3) which on thermolysis in refluxing toluene furnishes [Os-3(CO)(7)(CNBut){mu(3)-Ph2PCHP(Ph)C6H4}(mu-H)(2)] (4). Reaction of the labile complex [Os-3(CO)(9)(mu-dppm)(NCMe)] (5) with (BuNC)-Bu-t at room temperature affords the substitution product [Os-3(CO)(9)(mu-dppm)(CNBut)] (6). Thermolysis of 6 in refluxing toluene gives 4. On the other hand, the reaction of unsaturated [Os-3(CO)(9){mu(3)-eta(2)-C7H3(2-Me)NS}(mu-H)] (7) with (BuNC)-Bu-t yields the addition product [Os-3(CO)(9)(CNBut){mu-eta(2)-C7H3(2-Me)NS}(mu-H)] (8) which on decarbonylation in refluxing toluene gives unsaturated [Os-3(CO)(8)(CNBut){mu(3)-eta(2)-C7H3(2-Me)NS}(mu-H)] (9). Compound 9 reacts with PPh3 at room temperature to give the adduct [Os-3(CO)(8)(PPh3)(CNBut){mu-eta(2)-C7H3(2-Me)NS(mu-H)] (10). Compound 8 exists as two isomers in solution whereas 10 occurs in four isomeric forms. The molecular structures of 3, 6, 8, and 10 have been determined by X-ray diffraction studies. (C) 2008 Elsevier B. V. All rights reserved.