Investigations of aryl substituents electronic effects in the catalytic behavior of thermostable α-diimine nickel (II) catalyst on ethylene polymerization

In a-diimine-based catalytic systems, it is highly challenging to increase the thermal stability of the a-diimine Ni(II) catalyst. In this work, we are focused on examining the polymerization of ethylene by a number of a-diimine Ni(II) complexes with camphyl backbone and various electron-donating and withdrawing substituents as catalysts. The synthesized camphyl-based ligands were characterized by H-1 nuclear magnetic resonance (NMR), C-13 NMR, H-H correlation spectroscopy, Fourier-transform infrared (FT-IR), and elemental analysis. The formation of the Ni(II) complexes was approved by the far infrared (Far-IR) and energy dispersive x-ray spectroscopy (EDS). The Box-Behnken method was used to select the optimal polymerization conditions. The ligand electronic effect on the catalytic activity of Ni(II) complexes in ethylene polymerization was systematically investigated. All of the synthesized complexes were active in ethylene polymerization with activities at 10(5) g of polyethylenes (PE) (mol of Ni h)(-1). The electron-withdrawing substituent catalyst exhibited high activity in ethylene polymerization.