Activation of hydrogen and related small molecules by the unsaturated cluster complex PtOs3(CO)7(PBu3t)(μ-PBu2t)(μ4-CHCMeCH)

Reactions of the unsaturated mixed metal cluster complex PtOs3(CO)(7)(PBu3t)(mu-PBu2t)(mu(4)-CHCMeCH), 1, with hydrogen, HGePh3, and PhC2H have been investigated. Compound 1 reacts reversibly with hydrogen at room temperature to yield the dihydrido Complex PtOs3(CO)(7)(PBu3t)(mu-PBu2t)(mu(4)-CHCMeCH)(mu-H)(H), 2. A computational analysis shows that the hydrogen addition occurs by oxidative addition at the electronically unsaturated platinum atom and passes through two unstable intermediates before giving the final product 2. Compound 1 reacts with HGePh3 at the Ge-H bond to form the complex PtOs3(CO)(7)(PBu3t)(mu-PBu2t)(mu(4)-CHCMeCH)(GePh3)(mu-H), 3, but in this reaction the HGePh3 addition occurred at one of the osmium atoms and a CO ligand was shifted to the platinum atom. Compound 1 reacts with PhC2H by loss of the platinum atom and the PBUt3 ligand to give the compound Os-3(CO)(7)(mu-PBu2t)[mu(3)-eta(5) -CHCMeC(H)CCPhH], 4. In the process, the PhC2H molecule became bonded to the CHCMeCH ligand in I and its hydrogen atom was shifted to the phenyl-substituted carbon atom to form a triply bridging CHCMeC(H)CCPhH ligand. All of the products were characterized by single-crystal X-ray diffraction analyses.