Enhancing α-Diimine Catalysts for High-Temperature Ethylene Polymerization

Sterically demanding 2,6-bis(diphenylmethyl)-4-methylaniline was condensed onto acenaphthenequinone via an aminoalane intermediate and metalated using nickel(II) dibromide dimethoxyethane adduct to yield bis[(2,6-dibenzhydry1-4-methylimino) acenaphthene]dibromo nickel(II). This alpha-diimine precatalyst was examined for high-temperature ethylene polymerization and proved to be thermally robust at temperatures as high as 90 degrees C, demonstrating enhanced activity as compared with related catalysts. Furthermore, the resultant polymers displayed increased melting transitions as compared with those produced using catalysts with identical N-aryl moieties appended to nonacenaphthenequinone-derived ligand backbones.