REDUCTION OF COORDINATED CARBON-DIOXIDE BY TRANSITION-METAL HYDRIDES

The reactions of (eta-5-C5H5)2Mo(eta-2-CO2) (1) with the transition-metal hydrides HCo(CO)4 and H2Fe(CO)4 have been examined. 1 reacts with excess HCo(CO)4 rapidly at -78-degrees-C to produce [(eta-5-C5H5)2MoH(CO)]Co(CO)4 (2), HCo3(CO)9, and H2O. (CO2)C-13-labeling experiments indicate that the original CO2 in 1 is converted to coordinated CO in 2. Complex 2 slowly converts to a novel unsymmetrically bridged hydrido complex (eta-5-C5H5)2Mo(mu-H)(mu?? -CO)Co(CO)3 (3) whose structure has been established by X-ray diffraction. Complex 1 also reacts with excess H2Fe(CO)4 to produce [(eta-5-C5H5)2MoH(CO)]-[HFe3(CO)11] (4).