Nickel complexes bearing 2-(1H-benzo[d]imidazol-2-yl)-N-benzylidenequinolin-8-amines: Synthesis,structure and catalytic ethylene oligomerization

A series of 2-(1H-benzod]imidazol-2-yl)-N-benzylidenequinolin-8-amines was synthesized and characterized. They are stable as solids while displaying a tendency to decompose in solution. On reaction with NiCl₂, different coordination pattern sets of L·NiCl₂ or L₂Ni]²⁺·2Cl⁻ are obtainable in THF or ethanol. When activated by Et₂AlCl, the complexes L·NiCl₂ exhibit good to high catalytic activities and selectivities for 1-C₄ in ethylene oligomerization, while the complexes L2Ni]²⁺·2Cl⁻ hardly showed any activity, which is attributable to nickel coordination by two ligands barring interaction of ethylene with the metal center.