Synthesis, Characterization, and Ethylene Oligomerization of Nickel Complexes BearingN-((Pyridin-2-yl)methylene)quinolin-8-amine Derivatives

A series of nickel complexes ligated by N -((pyridin-2-yl)methylene)quinolin-8-amine derivatives were synthesized by one-pot reaction of 8-aminoquinolines, 1-(pyridine-2-yl) ketones, and nickel halides and characterized by elemental and spectroscopic analyses along with X-ray diffraction analyses. These nickel complexes exhibit two kinds of structures, namely, dimeric with octahedral-coordinated geometry and monomeric with distorted trigonal-bipyramidal geometry, in their solid states. Activated by Et 2 AlCl, these Ni(II) complexes exhibited good to high catalytic activities for ethylene oligomerization, and activity up to 4.9 × 10 7 g mol -1 (Ni) h -1 was observed in the catalytic system with Cy 3 P as auxiliary ligand. The steric and electronic influence of the substituents as well as the influence of different catalytic conditions was carefully investigated. In particular, the correlations between reactivity and auxiliary R 3 P ligands were examined.