Equilibrium between a Hydroxycarbene Complex and a Metal Acyl Hydride Complex

摘要

The amphiphilic rhenium carbene complex Cp(CO)_2-Re=CDCH_2CH_2CMe_3 undergoes stereospecific addition of HCl to produce a single diastereomer of cis-Cp(CO)_2ClReCHDCH_2-CH_2CMe_3, but the absolute stereochemistry of the process could not be determined in part because rotation about the Re=C bond is expected to be fast. In the course of synthesizing a rotationally restricted rhenium carbene complex having a two-carbon link between the cyclopentadienyl ligand and the carbene carbon atom, we discovered an equilibrium between the hydroxycarbene complex (CO)_2Re=C(OH)CH_2CH_2(η~5-C_5H_4) (1) and the isomeric metal acyl hydride complex trans-(CO)_2HReC(=O)CH_2CH_2(η~5-C_5H_4) (2).