Activation or utilization of carbon dioxide (CO2) is widely studied, owing to their environmental concerns and high abundant and CO2 has the most attractive applications as C1 source in organic synthesis due to their non-toxic and non-corrosive nature. However, the inertness of CO2 makes it very difficult to activate. Several methods have been developed, and among them, one of the very interesting methods is atom-economical synthesis of five membered cyclic carbonates from CO2 and propylene oxides (Scheme 1). Due to the various applications of the cyclic carbonates such as aprotic polar solvents, electrolyte, starting material of poly carbonates and polyurethane, and raw material for the chemical reactions, conversion of CO2 to cyclic carbonatehas gained much attention.
Previously, Co(III), Al(III) and Cr(III) complexes with salen ligand derivatives were studied elaborately with different cocatalysts. Similarly, ionic liquids were used to successfully convert the CO2 to cyclic carbonate with propylene oxides. However synthesis ofcyclic carbonate from CO2 and propylene oxide using the metal complexes and the ionic liquids was conducted at high CO2 pressure and temperatures. Additionally some of the catalysts afford the mixture of polycarbonate and cyclic carbonate, and most of the metal catalysts were highly sensitive to water molecule which deactivates the catalyst. Herein, we report the Cp*-Rh(III) complex, where Cp* is pentamethylcyclopentadiene, catalyzed formation of cyclic carbonate from CO2 and propylene oxide, under mild conditions without the influence of moisture.