Polymer Microstructure Control in Catalytic Polymerization Exclusively by Electronic Effects of Remote Substituents

A series of (κ2‐N,O)salicylaldiminato nickel methyl pyridine complexes 8a–h‐pyr bearing 2,6‐di‐(4‐R′‐phenyl)phenyl groups on the imine nitrogen and varying in the remote substituents [R′=C8F17 (a), CF3 (b), F (7c), H (d), Me (e), tert.‐butyl (f), OMe (g), and NMe2 (h)] were studied as precatalysts for ethylene polymerization. Complexes 8a–h‐pyr catalyze the polymerization of ethylene to low molecular weight polyethylene. Decreasing molecular weight and increasing degrees of branching are observed in the order R′=C8F17≈CF3>F>H>Me>MeO>tert‐butyl>NMe2. X‐Ray diffraction analysis of complex 8c‐pyr and polymerization results obtained with complexes 8‐pyr indicate that it is not the sterics but the electronics of the R′ group that control the polymer microstructure. This is a rare example of a polymerization catalyst in which substituents effects can clearly be traced to electronics exclusively.