Novel Non-bridged Metallocene Catalysts: Synthesis, Characterization And Catalysis Performance For Olefin Polymerization

Polypropylene can be produced with different stereochemical configurations, such as isotactic polypropylene(i PP), syndiotactic polypropylene(s PP) and atactic polypropylene(a PP). The side-methyls of a PP distribute randomly along the main amorphous polymer chain. Therefore a PP have some unique properties compared with general polypropylene resin. a PP with high molecular weight was elastomeric and have special flexibility and damping properties. a PP without unsaturated bond is a new polyolefin elastomer, which is better than ordinary diene rubber in antioxidant and anti-aging properties, so it can replace the existing EPR and poor heat resistant unsaturated rubber in some areas. a PP have a bright future in many different fields including medical equipment, commodity, defense industry and other aspects. In addition, a PP with high molecular weight possesses good optical performance. Therefore, it have a broad prospects in the field of special-purpose optical materials.A new half-sandwich pentamethylcyclopentadienyl titanium(IV) aryl(pyridyl)amide complexe, Cp*Ti Cl2[N(Ar)(2-Py)] [2,6-Et2Ph(2)], has been synthesized from the reaction of Cp*Ti Cl3 with the lithium salt of the corresponding aryl(pyridyl)amide ligand in toluene based on our previous work. A byproduct with two aryl(pyridyl)amide ligands, Cp*Ti Cl[N(4-Me Ph)(2-Py)]2(5) was also obtained from the synthetic reaction of complex 4 in a small amount. The new titanium complexes 2 were characterized by 1H and 13 C NMR and elemental analyses. The molecular structures of complexes 2, 4 and 5 were determined by single-crystal X-ray diffraction analysis. The results demonstrate that complexes 2 and 4 possess a relatively crowded hepta-coordinating environment surrounding the central titanium atom. Upon activation with AliBu3 and Ph3CB(C6F5)4, complexes 1–4 exhibited moderate to high catalytic activity for propylene polymerization, producing high molecular weight atactic polypropylene.Chromium-based catalysts for olefin polymerization occupy a very important position in the field of olefin polymerization, but characterization is rather difficulty for the paramagnetic Cr(III) complexs. Therefore, few homogeneous Cr(III) catalysts were reported, and for catalytic ethylene / α-olefin copolymerization are rare.In the third chapter, we synthesized four new ligands that have different electronic and steric effect based on 9-bromo-9-borafluorene. The new ligands HL6–HL9 were characterized by 1H NMR, 13 C NMR, 11 B NMR and LC-MS. Four corresponding zwitterionic half-metallocene chromium complexes [Cp*Cr Cl]+[BFl-(R)2]– [R = 2-Py(6), 6-Me-2-Py(7), Oxi Pr(8), Oxt Bu(9)] was synthesized and the complexes were characterized by elemental analysis. The molecular structures of complexes HL7 and 6 were determined by single-crystal X-ray diffraction analysis. The results demonstrate that complexes 6 possess a hexa-coordinating environment surrounding the central chromium atom. Upon activation with Al Et3, complexes 6–9 exhibited high catalytic activity for ethylene polymerization, producing high molecular weight polyethylene as spherical particles. While upon activation with a small amount of Al Et3, complexes 6–9 exhibit general catalytic activity for ethylene/NBE copolymerization.