The activation and transformations of vinyl acetate at a dirhenium carbonyl center

The reaction of Re2(CO)8(μ-C6H5)(μ-H), 1 with vinyl acetate in methylene chloride by heating at 40 °C yielded three new products: Re3(CO)13(μ-η2-C2H3), 3, (24% yield), Re2(CO)8(μ-η2-O2CCH3)(μ-H), 4, (9% yield) and Re2(CO)8(μ-η2-CHCHO2CCH3)(μ-H), 5, (13% yield). Compound 3 was also obtained in a similar yield from the reaction of Re2(CO)8(μ-H)[μ-η2-C(H) = C(H)Bun], 2 with vinyl acetate, but compounds 4 and 5 were not obtained. All of the products were characterized structurally by single-crystal X-ray diffraction analysis. Compound 3 consists of an open trirhenium cluster containing two rhenium – rhenium bonds. One of the rhenium – rhenium bonds contains a μ-η2-(σ+π)-coordinated C2H3 (vinyl) ligand. Compound 4 contains two rhenium atoms with a bridging η2-acetate ligand and a bridging hydrido ligand. Compound 5 contains two mutually bonded Re–Re atoms with a bridging (σ+π)-coordinated acetate-substituted vinyl group and a bridging hydrido ligand by the cleavage of one of the CH bonds on the β–carbon atom of the vinyl group of the vinyl acetate. The reaction of compound 3 with I2 resulted in cleavage of the Re(CO)5 group to yield the known complex Re(CO)5I and the new dirhenium complex Re2(CO)8I(μ-η2-C2H3), 6 containing a μ-η2-(σ+π)-coordinated vinyl group.