Synergistic effects of methoxy and Benzhydryl substituents in α-Diimine nickel catalysts for Homo- and copolymerization of 1-Hexene and norbornene

• Unsymmetrical α-diimine nickel(II) catalysts bearing ortho-bulky dibenzhydryl and electron-donating N-aryl substituents were synthesized, fully characterized, and applied in the homo- and copolymerization of 1-hexene and norbornene , exhibiting high catalytic activity. • These catalysts produced highly branched poly(1-hexene) with high molecular weight in 1-hexene homopolymerization. • Additionally, they enabled improved thermal stability in polymer materials obtained from the homo- and copolymerization of norbornene and 1-hexene, with tunable 1-hexene incorporation in the copolymerization. A series of unsymmetrical α-diimine nickel(II) catalysts bearing ortho -bulky dibenzhydryl and electron-donating N -aryl substituents were synthesized, fully characterized, and applied in the homo- and copolymerization of 1-hexene and norbornene. These catalysts exhibited high catalytic activity and remarkable polymerization efficiency upon activation with MAO and B(C 6 F 5 ) 3 . In the homopolymerization of 1-hexene, the catalysts demonstrated turnover frequencies up to 78 h −1 , yielding highly branched, high-molecular-weight poly(1-hexene) (M n : 182 kg mol −1 ). For norbornene polymerization, the highest catalytic activity of 2.61 × 10 4 g mol −1 h −1 and polynorbornene molecular weight of 274 kg mol −1 were achieved. The copolymerization of norbornene and 1-hexene yielded copolymers with tunable 1-hexene incorporation (27.8–33.4 mol%) and high molecular weights (up to 106 kg mol −1 ), displaying excellent thermal stability (>400 °C). These findings highlight the synergistic effects of steric bulk and electronic modifications in enhancing catalytic performance and polymer properties.