2-[1-(2,6-Dibenzhydryl-4-methylphenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridylnickel(II) halides: Synthesis, characterization and ethylene oligomerization behavior

A series of nickel(II) halide complexes ligated by 2-[1-(2,6-dibenzhydryl-4-methyl-phenylimino)ethyl]-6-[1-(arylimino)-ethyl]pyridines was synthesized and characterized by FT–IR spectroscopy and elemental analysis. Single-crystal X-ray crystallographic studies revealed that the nickel halide complexes possess pseudo square-pyramidal geometry at nickel. Following screening with the co-catalysts Et2AlCl, MAO, MMAO and ethylaluminum sesquichloride (EASC, Et3Al2Cl3), EASC was chosen as the co-catalyst of choice, and activities as high as 2.5 × 106 g mol−1 (Ni) h−1 were observed for ethylene oligomerization. The influence of the ligands and of the reaction parameters on the catalytic behavior of the nickel pre-catalysts was investigated.

Graphical abstractThe series of nickel(II) halide complexes ligated by 2-[1-(2,6-dibenzhydryl-4-methyl-phenylimino)ethyl]-6-[1-(arylimino)-ethyl]pyridines, activated with ethylaluminum sesquichloride (EASC, Et3Al2Cl3), exhibited high activities in ethylene oligomerizations.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A series of 2-[1-(2,6-dibenzhydryl-4-methylphenylimino)ethyl]-6-[1-(arylimino)-ethyl]pyridylnickel halides. ► The molecular structures of the nickel halides are described as pseudo square-pyramidal geometry. ► Upon activation with Et3Al2Cl3, all nickel pre-catalysts exhibited high activities in ethylene oligomerization. ► The selectively dimerization and high selectivity for 1-butene.