Synthesis, characterization and ethylene oligomerization behavior of 2-(chloro-substituted-1H-benzoimidazol-2-yl)-6-(1-aryliminoethyl)pyridylnickel dihalides

A series of 2-(chloro-substituted-1H-benzoimidazol-2-yl)-6-(1-aryliminoethyl)pyridines (L1–L6) was synthesized and fully characterized. They reacted with NiCl2 or (DME)NiBr2 to form the corresponding N^N^N tridentate nickel dichlorides (C1–C6) or dibromides (C7–C12). All nickel complexes were characterized by elemental analysis and infrared spectroscopy, while the X-ray diffraction study reveals the distorted octahedral geometry of representative nickel dichloride complex C3 and nickel dibromide complex C7. All nickel complexes, activated with either Et3Al2Cl3 or Et2AlCl, showed good activities in ethylene oligomerization, and notably remarkably high selectivity of α-olefins was achieved in the presence of Et3Al2Cl3. The chloro-substituted ligands enhanced the activities of complexes in ethylene polymerization.