Synthesis And Catalytic Properties Of Novel Bidentate Metal Complexes

This dissertation focuses on designing and synthesis of remote benzhydryl-substituted symmertrical a-diimine ligands and their corresponding nickel complexes using 2,3-butanedione as backone. These new complexes was used as precatalyst for ethylene polymerization. Upon activation with cocatalyst Et2AlCl, all nickel complexes exhibited high activity toward ethylene polymerization. The influence of polymerization condition (polymerization temperature, Al/Ni ratio, ethylene pressure, etc) were investigated in detail. Systematic studies of the effects of ligand structure and polymerization conditions on the catalytic properties.Three parts are included in this dissertation as follows:Part Ⅰ:Introduced the progress of the developing olefin polymerization in recent years and described the development process of several typical olefin polymerization catalyst systems in detail, especially focusing on the development of the late-trasition metal catalyst.Part Ⅱ:The ligand containing bulky substituent were synthesized by the condensation reaction of 2,3-butanedione and various 4-benzhydrylphenylamine dervatives, and the organic compounds were characterized by FT-IR, NMR measurements as well as elemental analysis. All these compounds reacted stoichiometrically with (DME)NiBr2 and the corresponding nickel(Ⅱ) complexes were afforded in reasonable yields. All the complexes were comfirmed by FT-IR, elemental analysis. In additon, a representative complex was futher confirmed by single crystal X-ray diffraction.Part Ⅲ:Upon activation with cocatalyst Et2AlCl, different conditions ((polymerization temperature, ethylene pressure and time), Al/Ni molar ratio and ligands environment were tested for ethylene polymerization.The results showe all nickel complexes exhibited high activity toward ethylene polymerization, producing polyethylenes with high molecular weights and high linearity.