Thermally robust α-diimine nickel and palladium catalysts with constrained space for ethylene (co)polymerizations

Abstract

The axial and equatorial plane model has been widely accepted for α-diimine nickel and palladium catalysts of olefins polymerization. In this paper, dinaphthobarrelene backbone-based α-diimine nickel and palladium complexes with the constrained space were designed and synthesized from the viewpoint of three-dimensional (3D) space. The 3D-constrained microenvironment around the Ni/Pd metal center created by the bulky ligand substituents fully shielded the back and axial sites, which improved catalytic activity, thermal stability, and living fashion of catalysts. Additionally, enhanced tolerance towards polar groups in copolymerization of ethylene and polar monomers was realized by dinaphthobarrelene-derived α-diimine nickel and palladium catalysts.