Enhancing Thermal Stability and Living Fashion in α‑Diimine–Nickel-Catalyzed (Co)polymerization of Ethylene and Polar Monomer by Increasing the Steric Bulk of Ligand Backbone

Development of thermally
stable nickel-based catalysts is highly
desirable for industrial gas-phase olefin polymerizations. On the
basis of the strategy of promoting the thermostability of nickel catalyst
by the ligand backbone, we herein reported novel dibenzobarrelene-derived
α-diimine nickel precatalysts for ethylene polymerization. Increasing
the steric bulk on the ligand backbone was expected to inhibit the N-aryl rotation of the α-diimine ligands by the repulsive
interactions, thus enhancing thermal stability (100 °C) and living
fashion a temperatures up to 80 °C. Bulk ligand backbone also
improved tolerance of nickel catalyst toward polar groups, and the
α-diimine nickel catalyst containing a 2,6-tBu-dibenzobarrelene backbone catalyzed living copolymerization
of ethylene and methyl 10-undecenoate.