Roles of CO₂ in Controlling the Chemoselectivity of [LCu-Fp] Heterobimetallic-Catalyzed CO₂ Hydroboration Reduction: A Computational Study

CO2 utilization can resolve serious climate warming problems and provide a new development direction in energy usage. In this work, the detailed mechanism of (IPr)­Cu-FeCp­(CO)2 ([LCu-Fp]) heterobimetallic-catalyzed hydroboration reduction of CO2 has been systematically investigated by DFT calculations. Our calculated results show that the catalytic reaction contains three steps, a [LCu-Fp] catalyst activated by HB­(pin) to form [LCu-H] and FpB­(pin), [LCu-H]-catalyzed CO2 hydroboration, and CO2-assisted formate decarbonylation catalyzed by FpB­(pin). HCO2B­(pin) (1) can be obtained easily catalyzed by [LCu-H], and the transformation of 1 to (pin)­BOB­(pin) (3) is catalyzed by FpB­(pin) but only in the presence of CO2. The formation of a Lewis adduct between 1 and FpB­(pin), with the reversible coordination of CO2 to Fp, facilitates the transformation. The chemoselectivity of the title reaction can be controlled by the reaction conditions: 1 is the main product under mild conditions when using a nonpolar solvent but by enhancing the polarity of the solution or under UV irradiation, the yield of 3 would increase. Our work provides deep mechanistic details and determines how CO2 plays a role in chemoselectivity for the [LCu-Fp] heterobimetallic-catalyzed hydroboration reduction of CO2.