Rational design of aldimine imidazolidin-2-imine/guanidine nickel catalysts for norbornene (Co)polymerizations with enhanced catalytic performance

The development of late transition metal catalysts bearing novel ligand platforms is a convenient path-way to obtain prospective systems with enhanced catalytic performance, however, it remains a challenge in the field of olefin (co)polymerizations. In this contribution, a new family of [N,N]-type of bidentate aldimine imidazolidin-2-imine/guanidine ligands and their nickel complexes Ni1-Ni7 bearing a distinct six-membered chelate ring were successfully synthesized, and characterized. All of the nickel catalysts were active for norbornene polymerization with high activity of up to 7.44 x 105 g mol-1 h-1. These cat-alysts also copolymerized norbornene and 1-alkenes (1-dodecene and 1-octadecene) while keeping high activities to produce various norbornene-based high-molecular-weight (Mn = 5.75-36.0 kg mol-1) cyclic olefin copolymers (COCs) with adjustable 1-alkene incorporations (1.44-13.30 mol%) and a wide range of Tg values (102.2-271.4 degrees C). Moreover, with the decoration of bulky N-aryl substituents, these nickel cat-alysts exhibited strong tolerance towards polar monomer to promote the direct copolymerization of nor-bornene and methyl 10-undecenoate with high activity (up to 9.88 x 104 g mol-1 h-1), and furnished polar functionalized COCs with a high molecular weight (Mn up to 72.4 kg mol-1) and reasonable polar monomer incorporations (0.19-0.45 mol%). These nickel complexes are rare examples and also promising candidates as catalysts for the efficient synthesis of various COCs.(c) 2023 Elsevier Inc. All rights reserved.

Automated summary

A new family of [N,N]-type bidentate aldimine imidazolidin-2-imine/guanidine ligands and their nickel complexes were synthesized and characterized. These nickel catalysts exhibited high activity for norbornene polymerization and copolymerization with 1-alkenes, producing various norbornene-based high-molecular-weight cyclic olefin copolymers. The nickel complexes also showed tolerance towards polar monomers, promoting the direct copolymerization of norbornene and methyl 10-undecenoate.