Phosphine–Urea-Supported Nickel Catalyst for Ethylene/Acrylate Copolymerization

A new class of phosphine–urea supported nickel polymerization catalysts has been synthesized. The utility of this class of catalysts for the polymerization of ethylene and acrylate comonomers has been investigated. Carbazole-based urea ligands were found to be uniquely suited for this chemistry. Reaction with bis(pyridine)bis(trimethylsilylmethyl)nickel(II) enables access to stable nickel complexes bearing a single anionic, bidentate phosphine–urea ligand, which proved critical for obtaining meaningful catalytic activity and stability. Structure–activity relationships were established for both the carbazole and phosphine substitution, and it was determined that the catalyst performance is more sensitive to phosphine substitution. This new class of catalysts enabled to access a wide range of ethylene/tert-butyl acrylate copolymer molecular weights and acrylate incorporations.