Activation of the carbon—nitrogen triple bond of benzonitrile in the presence of triosmium clusters and acetic acid. Crystal structure of (μ-H)Os 3(CO) 10(μ-O 2CCH 3), a product of the reaction

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The activation of the CN triple bond of benzonitrile in the presence of acetic acid and of Os 3(CO) 12 or H 2Os 3(CO) 10 has been studied. When Os 3(CO) 12 reacts with PhCN and acetic acid in refluxing n-octane the three main products are (μ-H)Os 3(CO) 10(μ-O 2CCH 3) (I), (μ-H)Os 3(CO) 10(μ-NCHPh) (II) and (μ-H)Os 3(CO) 10(μ-NHCH 2Ph) (III); II and III are analogues of (μ-H)Ru 3(CO) 10(μ-NCHPh) and (μ-H)Ru 3(CO) 10(μ-NHCH 2Ph) obtained from PhCN, Ru 3(CO) 12 or H 4Ru 4(CO)] 12, and acetic acid. In contrast to the reaction with ruthenium clusters, Os 3(CO) 12 and H 2Os 3(CO) 10 also give the adduct Os 3(CO) 10(CH 3COOH) (I). The structure of I has been fully elucidated by X-ray diffraction. Crystals of I are monoclinic, space group P2 1/ m, with unit cell parameters a 7.858(6), b 12.542(8), c 9.867(6) Å, β 109.92(2)°, Z = 2. In I an edge of the triangular cluster of osmium atoms is doubly bridged by a hydride and an acetate ligand. Ten terminal carbonyl groups are bonded to the metal atoms.