Computational Study of Low-Coordinate Rhenium Diolates, Metallaoxetanes, Oxo Complexes, and Carbenes

CCSD energies with a triple-ζ quality basis set at DFT geometries show that low coordination numbers favor metallaoxetane over diolate isomers in high-valent rhenium complexes. Minima and transition states are located and used to rationalize recently published experimental studies of the gas-phase chemistry of the title complexes. The experimental and theoretical studies shed light on the related chemistry of isoelectronic osmium complexes involved in catalytic asymmetric dihydroxylation.