Robust and Reactive Neutral Nickel Catalysts for Ethylene Polymerization and Copolymerization with a Challenging 1,1-Disubstituted Difunctional Polar Monomer

A series of methyl nickel complexes with phosphino-naphtholate chelate ligands have been strategically designed, synthesized, and fully characterized. These catalysts showed extremely high activity toward ethylene polymerization and ethylene/unsaturated acid ester copolymerization without any activator under mild conditions. The catalytic activity for ethylene polymerization was up to 3.0 × 107 gPE molNi–1 h–1, which was the topmost among the neutral nickel catalysts previously reported. Besides, the catalytic activity for ethylene/methyl acrylate (MA) copolymerization was also outstanding (up to 3.7 × 105 g molNi–1 h–1) among the representative Ni and Pd catalytic systems, which could mediate E/MA copolymerization. More remarkably, a very challenging 1,1-disubstituted difunctional ethylene comonomer, dimethyl itaconate, was copolymerized with ethylene by these catalysts to give end-difunctional polyethylene with double ester groups and molecular weight up to 10 700 directly.