REDUCTION OF A COORDINATED CARBON-MONOXIDE TO AN OXYMETHYL-BRIDGING GROUP - SYNTHESIS AND X-RAY CHARACTERIZATION OF THE DIANION {[RE3(MU-H)3(MU-3-ETA-2-CH2O)(CO)9]2-}

The reaction of [Re3(μ-H)4(CO)10]- with Li[BH(s-Bu)3] gives in high yields the novel anion [Re3(μ-H)3(CH2O)(CO)9] 2-, which contains a μ3-η2-oxymethyl ligand, representing a type of intermediate of CO hydrogenation never previously fully characterized. Protonation at -80°C leads to an unstable hydroxymethyl derivative, characterized by NMR, which under CO, at room temperature, converts in fair yields to [Re3(μ-H)2(CO)12]- and methanol.