Development of N-Phosphinomethyl-Substituted NHC-Nickel(0) Complexes as Robust Catalysts for Acrylate Salt Synthesis from Ethylene and CO2.

By using a nickel complex with an N-phosphinomethyl-N-heterocyclic carbene ligand (NHC-P), the reducing ability and thermal stability of the complex were improved considerably compared to the previously reported bipyridine and bisphosphine complexes, and acrylate salt was prepared from ethylene and CO2 with the highest TON ever reported for nickel systems even without using metallic zinc. Oxidative cyclization of ethylene and CO2 on the NHC-P nickel complex was found to proceed very rapidly compared to previous systems.