Synthesis, structure and ethylene oligomerization behavior of non-symmetric bidentate neutral arylnickel(II) phosphine complexes

A series of new neutral arylnickel(II) phosphine complexes bearing non-symmetric bidentate chelate ligands, 3-aryliminomethyl-5-chloro-2-hydroxybenzaldehyde, have been synthesized, and the structure of representative complexes (2b and 2d) has been confirmed by X-ray crystallographic analysis. These neutral arylnickel(II) phosphine complexes have been investigated as catalysts for ethylene oligomerization. Using methylaluminoxane (MAO) as a cocatalyst, these complexes display high ethylene oligomerization activities. A catalytic activity of up to 4.6 × 106 g mol−1 h−1 has been observed. The influence of Al/Ni molar ratio, reaction temperature, reaction period and pressure on catalytic activity was investigated.