N-(5,6,7-Trihydroquinolin-8-ylidene)arylaminonickel dichlorides as highly active single-site pro-catalysts in ethylene polymerization

A series of N-(5,6,7-trihydroquinolin-8-ylidene)arylamine ligands was synthesized and fully characterized by NMR, IR spectroscopy and elemental analysis. Dimeric N-(5,6,7-trihydroquinolin-8-ylidene)arylaminonickel dichlorides were prepared and examined by IR spectroscopy and elemental analysis, and the molecular structures of the representative nickel complexes were determined by the single crystal X-ray diffraction. On treatment with various alkylaluminiums, all the title complexes exhibited highly active, single-site active behavior for ethylene polymerization producing polyethylene (PE) waxes. The catalytic systems using the co-catalysts diethylaluminium chloride (Et2AlCl) or methylaluminoxane (MAO) were investigated in detail, and the molecular weights and distributions of the PEs obtained were found to significantly rely on the nature of the different ligands present and reaction parameters such as the molar ratios of Al/Ni, reaction temperature and reaction time.