Mechanistic studies of P,O-chelated nickel complexes targeting functional polyolefin synthesis

The efficient copolymerization of ethylene with functionalized olefins using Ni catalysts remains a challenge. Herein, we report two neutral Ni(II) catalysts that exhibit high thermal stability and significantly higher incorporation of acrylates or improved resistance to acrylate-induced chain transfer, in comparison to previously reported catalysts. Nickel alkyl complexes generated after tBA insertion were isolated and, for the first time, characterized by crystallography. Experimental kinetic studies of six cases of monomer insertion with aforementioned nickel complexes indicate that pyridine dissociation and monomer coordination are fast relative to monomer migratory insertion and that monomer enchainment after acrylate insertion is the rate limiting step of copolymerization.