Fluorine and hydroxyl containing unsymmetrical a-diimine Ni (II) dichlorides with improved catalytic performance for ethylene polymerization

A series of new tailored a-diimine Ni (II) complexes (Ni-OH, Ni-FOH, Ni-PhOH, and Ni-PhFOH) containing bulky ortho-N-aryl groups with various dibenzhydryl substitutes was successfully synthesized, characterized applied in ethylene polymerization. The ligands were by 1H, 19F, 13C NMR, elemental analysis, high resolution electrospray ionization mass spectrometry (ESI-HRMS). X-ray crystallographic study metal Ni-OH, Ni-PhFOH revealed their distorted tetrahedral geometry. An unsymmetrical steric-enhancement design approach employed to modulate the competition between monomer insertion chain-walking process This facile resulted a catalytic activity yielded molecular weight PE. these optimized varying polymerization conditions (temperature, time, pressure), use co-catalysts variation Al/Ni ratio. When activated modified methylaluminoxane (MMAO), exhibited as 29.1 × 106 g PE (mol Ni)−1 h−1), 1.81 mol−1. Their thermal stability well pronounced at elevated temperatures; 2.88 h−1 (0.86 mol−1obtained 90 °C). PEs tunable branches melting points (127.5 °C) obtained, which is typical feature LLDPE. incorporation fluorine atoms on N-aryl had strong positive influence favored chain-growth Surprisingly, simultaneous presence terminal hydroxyl group did not adversely affect activity, while offering possibility for covalent attachment solid supports future heterogeneous