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 [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] (2) with tBuNC at room temperature gives [Os3(CO)8(CNBut)){μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] (3) which on thermolysis in refluxing toluene furnishes [Os3(CO)7(CNBut){μ3-Ph2PCHP(Ph)C6H4}(μ-H)2] (4). Reaction of the labile complex [Os3(CO)9(μ-dppm)(NCMe)] (5) with tBuNC at room temperature affords the substitution product [Os3(CO)9(μ-dppm)(CNBut)] (6). Thermolysis of 6 in refluxing toluene gives 4. On the other hand, the reaction of unsaturated [Os3(CO)9{μ3-η2-C7H3(2-Me)NS}(μ-H)] (7) with tBuNC yields the addition product [Os3(CO)9(CNBut){μ-η2-C7H3(2-Me)NS}(μ-H)] (8) which on decarbonylation in refluxing toluene gives unsaturated [Os3(CO)8(CNBut){μ3-η2-C7H3(2-Me)NS}(μ-H)] (9). Compound 9 reacts with PPh3 at room temperature to give the adduct [Os3(CO)8(PPh3)(CNBut){μ-η2-C7H3(2-Me)NS(μ-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.