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, we report anionic mono(formazanate) iron(II) complexes bearing labile halide ligands, which possess both Lewis acidic and nucleophilic functionalities, 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 were investigated by employing complexes 1-3 with and without an additional nucleophile. Very high selectivity was achieved towards the formation of the cyclic carbonate product for various terminal and internal epoxides without the need of a co-catalyst.