Nickel complexes bearing 2-(1H-benzimidazol-2-yl)-phenoxy ligands: Synthesis, characterization and ethylene oligomerization

A series of 2-(1 H -benzimidazol-2-yl)-phenols and their nickel complexes have been synthesized and characterized by elemental and spectroscopic analysis. The molecular structures of ligand L4 and complex C5 were confirmed by X-ray diffraction analysis. X-ray crystallographic analysis revealed that complex C5 has a six-coordinated distorted octahedral geometry. Upon activation with Et 2 AlCl, these nickel(II) complexes showed good activity for ethylene oligomerization. When PPh 3 was added as an auxiliary ligand to the catalytic system, an increased activity as high as 1.60 × 10 7 g mol −1 (Ni) h −1 was observed. The ligand environment and reaction conditions remarkably affected the catalytic behavior of these nickel complexes.