Amidine/Phosphine‐Oxide‐Based Nickel Catalysts for Ethylene Polymerization and Copolymerization

Abstract

AbstractNickel catalyzed copolymerization of olefins with polar co‐monomers remains a great challenge in the field of olefin polymerization. In this contribution, a series of amidine/phosphine‐oxide‐based ligands were synthesized and investigated for nickel catalyzed ethylene polymerization and copolymerization with polar co‐monomers. These nickel catalysts exhibited high catalytic activities (homopolymerization: up to 2.6×106 g (mol of Ni)−1 h−1; copolymerization: up to 1.0×105 g (mol of Ni)−1 h−1;) and good thermal stabilities at 80 °C, generating high‐molecular‐weight polyethylenes (Mn up to 8.45×104 g mol−1) as well as copolymers (Mn up to 2.19×104 g mol−1). The Ni center exhibited square planar geometry. The N atom between the imine and phosphine‐oxide moieties exhibited trigonal planar geometry, indicating electron‐donating conjugate effect of the sp2 hybrid N‐atom linker. This electronic effect can increase the electron density on the nickel center and result in enhanced catalytic performance.