Nickel(II) complexes bearing 4,5-bis(arylimino)pyrenylidenes: synthesis, characterization, and ethylene polymerization behaviour.

A series of nickel(II) dihalides complexes bearing 4,5-bis(arylimino)pyrenylidenes, NiX2(2,6-R(1)-4-R(2)C6H2N)2C16H8, was synthesized and characterized by FT-IR spectroscopy, elemental analysis, and single crystal X-ray diffraction for the organic compounds (L2 and L3) and the nickel complexes (C1 and C2). The molecular structures of C1 (R(1) = Me, R(2) = H, X = Br) and C2 (R(1) = R(2) = Me, X = Br) revealed a distorted tetrahedral geometry around the nickel centre. Upon treatment with the co-catalysts MAO, EASC and MMAO, all the nickel pre-catalysts exhibited high activities (of up to 4.42 × 10(6) g(PE) mol(Ni)(-1) h(-1)) for ethylene polymerization, and produced polyethylene products with a high degree of branching (up to 130 branched per 1000 carbons) and narrow molecular weight distribution. The influence of the reaction parameters and the nature of the ligands on the catalytic behavior of the title nickel complexes have been investigated.