Ethylene polymerizations with unsymmetrical (alpha-diimine)nickel(II) catalysts

Abstract

Four unsymmetrical (alpha-diimine)nickel(II) catalysts were synthesized by sequential stepwise condensation of acenaphthenequinone with the corresponding aniline compounds and subjected to ethylene polymerizations with MAO. Interestingly, when the catalysts have the same composition of the ortho substituents, the catalyst with two ortho isopropyl substitients on one side and two ortho methyl substituents on the other side produced polyethylenes with higher branching densities and lower molecular weights than the catalyst with one ortho isopropyl and one ortho methyl substituent on each side. However, branch distribution was not changed by the position of the ortho substituents.