Synthesis, characterization and ethylene polymerization behavior of nickel dihalide complexes bearing bulky unsymmetrical alpha-diimine ligands

A series of nickel(II) dihalide complexes (C1-C10) bearing unsymmetrical alpha-diimine ligands of the type 2,4-dibenzhydryl-N-(2-phenyliminoacenaphthylenylidene)-6-methylbenzenamine (L1-L5) were synthesized and fully characterized. Single-crystal X-ray diffraction revealed a distorted tetrahedral geometry around the nickel center in the complexes C3, C5 and C9. Upon activation with modified methylaluminoxane (MMAO), all nickel pro-catalysts performed with high activities in ethylene polymerization, producing highly branched polyethylene products.