A New Approach to the Reduction of Carbon Dioxide: CO₂ Reduction to Formate by Transfer Hydrogenation in iPrOH

A series of four Ir and Ru catalysts have been tested in the reduction of CO2 to formate in the presence of H2. The iridium catalysts containing the basic NHC ligands were the ones to show better catalytic activities, achieving high TON values of up to 1800 TON. The unprecedented reduction of CO2 with iPrOH through a hydrogen transfer process is also described. TON values of up to 150 were obtained. Two other secondary alcohols, cyclohexanol and 1-phenylethanol, were also used as hydrogen sources for the reduction of carbon dioxide.