Hemilabile N‐heterocyclic carbene and nitrogen ligands on Fe (II) catalyst for utilization of CO2 into cyclic carbonate

Abstract

Six Fe (II) complexes were synthesized based on the concept of the hemilability of hybrid ligands, and their catalytic behaviors and performances were evaluated for the fixation of CO2 via the cycloaddition of epoxides. The catalytic potential of the Fe (II) complexes, in combination with bis(triphenylphosphoranylidene)ammonium chloride, have been proved to achieve the efficient conversion in some challenging substrates such as internal, disubstituted epoxides, oxetanes, and fatty acid‐derived epoxides for synthesis of cyclic carbonates under the mild reaction conditions. Ultraviolet–visible and in situ Fourier transform infrared spectroscopy experiments as well as our previous coordination of Ni complexes studies revealed that the origin of activity of Fe (II) complexes might be attributed to the trans effect between N‐heterocyclic carbene ligands and pyridine nitrogen donors.