A Constrained Structural Symmetry Strategy for Nickel-Catalyzed Olefin Polymerization and Copolymerization with Polar...

Conventional strategies for enhancing performance in α-diimine nickel-catalyzed olefin polymerization have predominantly focused on modulating steric hindrance and electronic properties. While effective in suppressing β-hydride elimination and increasing molecular weight, these approaches often lead to reduced incorporation of polar monomers in copolymerization reactions. Herein, we report a constrained structural symmetry strategy through the design of an oxa-macrocyclic α-diimine nickel catalyst, which enforces a specific spatial arrangement of the dibenzhydryl substituents on the same side of the N-Ni-N plane. Compared with the simulant catalyst bearing dibenzyl bulky groups on the opposite side, the topologically constrained catalyst exhibits higher activity (>10⁷ g·mol^-1·h^-1), produces polymer with a higher molecular weight, and also achieves enhanced polar monomer incorporation (up to 5.3 mol %) in copolymerization. These results underscore the unique role of structural symmetry manipulation in breaking the conventional trade-off between molecular weight control and polar comonomer incorporation, offering a new paradigm for designing high-performance olefin polymerization catalysts. Furthermore, the cyclic ether moiety can serve as an anchor to immobilize the catalyst on Lewis acid-modified silica. This heterogenization leads to increased polymer molecular weight, reduced branching density, and improved control over product morphology.