Synthesis of anionic rhenium carbonyl hydrides by the ring opening of rhenium carbonyl heterocycles

The heterocyclic rhenium–bismuth complex Re3(CO)12(μ-H)2(μ-BiPh2), 1 was obtained in 62% yield from the reaction of [Bu4N][Re3(CO)12(μ-H)2] with BiPh2Cl at room temperature. Compound 1 was converted to the [Bu4N] salt of the dihydrido monoanion [{HRe(CO)4}2(μ-BiPh2)], 2 by reaction with [Bu4N][OH]. The anion of 2 contains a BiPh2 ligand bridging two HRe(CO)4 groups. The corresponding [Bu4N] salt of the SbPh2-bridged monoanion [{HRe(CO)4}2(μ-SbPh2)], 4 was obtained from the reaction of Re2(CO)8(μ-SbPh2)(μ-H), 3 with NaBH4 followed by precipitation with [Bu4N]Br. The anion of 4 was converted back to 3 by treatment with H[BF4], but no characterizable product was obtained from the treatment of 2 with H[BF4]. The crystal and molecular structures of compounds 1, 2, and 4 were established by single-crystal X-ray diffraction analyses.