Transformation of a coordinated carbon monoxide into an oxyethyl bridging group in a hydrido-carbonyl rhenium cluster. Synthesis and crystal structure of the anion [Re3(μ-H)3(CO)9μ3-η2-C(H)(Me)O]2

The reaction of the unsaturated anion [Re3(μ-H)4(CO)10- with LiMe at low temperature gives the unsaturated acyl derivative [Re3(μ-H)4(CO)9C(Me)O]2-, which is slowly converted, as the temperature is raised, into a saturated species in which a hydride ligand has migrated from the cluster to the acylic carbon atom to give [Re3(μ-H)3(CO)9μ3-γ2-C(H)(Me)O]2-. Variable temperature 1H-NMR spectroscopy has shown the existence of an unexpected equilibrium between the two anions. © 1991.