New Transition Metal Catalysts For Olefin Polymerization

This thesis discussed the syntheses, characterization and catalytic activities for ethylene and norbornene polymerization concerning iron, nickel, cobalt, nickel, chromium, copper, and zinc halide complexes bearing chelating 2,6-bis(imino)pyridyl ligands (catl-15). X-ray single crystal diffraction showed the metal center's geometries of the cobalt and nickel complexes (cat2, cat12 and cat14 ) to be either distorted trigonal bipyramidal or distorted square pyramidal. Treatment of the iron, cobalt 2,6-bis(imino)pyridyl complexes (cat1, cat2, cat4 and cat5) with methylaluminoxane (MAO) leads to a highly active ethylene polymerization catalysts converting ethylene to highly linear polyethylene (PE), while the corresponding chromium complex (cat3) is disclosed as moderate catalytic activity for the polymerization of ethylene. In addition, the complexes cat1-3 and corresponding compounds of FeCl₂, CoCl₂(THF)_1.5 and CrCl₃(THF)₃ can also catalyze vinyl polymerization of norbornene activated with MAO and show good activities. The series of nickel complexes (cat10-15) activated with MAO lead to weak active catalysts for ethylene oligomerization, but show highly activities for vinyl norbornene polymerization. The systematical investigation using complex cat12 for vinyl norbornene polymerization showed that their productivities and molecular weights were greatly dependent on the ratio of nickel precursor to cocatalyst MAO and monomer norbornene, as well as on the reaction temperature and reaction time. However, the copper and zinc bis(imino)pyridyl complexes show no active for ethylene polymerization in the presence of MAO.