Design and Polymerization Behavior of Carbocyclic-Fused (Imino)Pyridine-Ligated Late-Transition-Metal Catalysts

Abstract Modern materials science increasingly demands precise control over polymer architecture, driving the development of innovative polymerization catalysts. Compared with heterogeneous systems, molecular metal catalysts offer clear advantages due to their well-defined structures and the ease with which their catalytic behavior can be tuned. In light of these advances, numerous new molecular catalysts have been developed for olefin and diene polymerization. Here we report a new class of late-transition-metal catalysts capable of promoting ethylene dimerization, trimerization, oligomerization, polymerization, as well as diene polymerization. The incorporation of carbocyclic rings into mono-iminopyridine and diiminopyridine ligands represents an advanced structural evolution of classical iminopyridine frameworks, enabling improved catalyst performance and stability. Emphasis is placed on structure–performance relationships in carbocyclic-fused (imino)pyridine-ligated catalysts and ligand modifications influence on activity, selectivity, and polymer properties. The discussion is organized according to metal type and polymerization behavior, with additional consideration of cocatalyst effects and reaction conditions. Synthetic strategies for these novel ligand systems are also briefly presented.