Highly Selective Single-Component Formazanate Ferrate(II) Catalysts for the Conversion of CO2 into Cyclic Carbonates

The development of new families of active and selective single-component catalysts based on earth-abundant metal is of interest from a sustainable chemistry perspective. In this context, anionic mono(formazanate) iron(II) complexes bearing labile halide ligands, which possess both Lewis acidic and nucleophilic functionalities, have been developed as novel single-component homogeneous catalysts for the reaction of CO2 with epoxides to produce cyclic carbonates. The influence of the halide ligand and the electronic properties of the formazanate ligand backbone on the catalytic activity are investigated by employing the iron(II) complexes with and without an additional nucleophile. Very high selectivity is achieved towards the formation of the cyclic carbonate products from various terminal and internal epoxides without the need of a cocatalyst.