Ansa-Cyclohexyl-bis（4,5,6,7-tertrahydro-l-indenyl） zirconium dichloride （5） was used as catalyst for propylene and ethylene polymerization together with methyl aluminoxane （MAO） as the cocatalyst. Isotactic polypropylene （PP） was obtained with the highest activity of 6.37× 107g PP （molZr）^-1h^-1. The mesomeso （mmmmm） pentads sequence content of PP was determined by 13C NMR spectroscopy. The dependence of the microstructure on the reaction temperature and the AI/Zr molar ratio was examined and the catalytic activity of complex 5 was compared with that of the similar ansa-zirconocene 3. The high activity of the new zirconocene 5 for propylene isospectic polymerization at high temperature （60℃） is the result of its unique bridged-group structure. Complex 5/MAO displays also high catalytic activity of 0.46× 10^6 to 9.87× 10^6g PE（molZr）^-h^-in the homo-polymerization of ethylene, The visometric molecular weight of PE ranges from 0.97×10^4 to 11.16×10^4 g.mol^- under the given conditions.^13C NMR spectroscopy analysis proves the PE to be linear polyethylene （LPE）.
Mononaclear carbon bridged cyclopentadienyl chromium complexes of the type [ （ C5H4 ） C （ C5 H10 ） CH2 （ C5 H4 N） ] CrCl2 （1） , [ （ C5 H4 ） C（ CH3 ）2 CH2 （ C5 H4 N） ] CrCl2 （ 2 ） and homodinuclear chromium complex of the type （ CH3 ）2 C｜ [ （ C5 H3 ） C（ CH3 ）2 CH2 （ C5 H4 N） ] CrCl2｜2 （ 3 ） were prepared by treutment of the lithium salts of eyclopentadiene ligands with pyridyl group with CrCl3 （ THF）3 in THF solution. All complexes were structurally charncterized by mass spectra and elemental analysis. The structure of complex 1 was determined by X-ray diffraction analysis. Activated by MAO , complexes 1 and 2 are efficient catalysts in the polywerization of ethylene yielding polyethylene （ PE ） with a high molecular weight （ My ranging from 225800 to 637800 g·mol^-1 , 30≤ Tp≤70℃ under 0.9 MPa monomer pressure ）. High activities of polymerization are related to the unique electronic and sterie structure of complexes 1 and 2 . The melting points of the polymers determined by OSC and charueterization data of ^13 C NMR all show the synthesis of linear polyethylene （LPE） with a low branching extent.
