Synthesis and polymerization catalytic properties of aryl-substituted tetramethylcyclopentadienyl zirconocenes (original) (raw)

2002, Journal of Molecular Catalysis A-chemical

A series of aryl-substituted tetramethylcyclopentadienyl zirconocenes (C 5 Me 4 C 6 H 4 X-4)Cp MCl 2 [Cp = C 5 H 5 , X = H (5), Me (6), Cl (7) or OMe (8); Cp = Ind, X = H (9), Me (10) or Cl (11); Cp = 2-Ph-Ind, X = H (12)] and (C 5 Me 4 C 6 H 4 X-4) 2 ZrCl 2 [X = H (13), Me (14), Cl (15)], with different substituents at the 4-position of phenyl, have been prepared by the reaction of the corresponding ligands (C 5 Me 4 HC 6 H 4 X-4) [X = H (1), Me (2), Cl (3) or OMe (4)] with n-BuLi, ZrCl 4 and Cp Li or with n-BuLi and ZrCl 4 . Ethylene polymerization with these complexes in combination with MAO has been studied. The electron donor (Me) at the 4-position of phenyl led to an increase in catalytic activity while the electron-withdrawing group (Cl) and the strong donor (OMe) led to its decrease. Complexes 5, 6, 9 and 10 exhibited very high activities, but 13-15 showed much lower activities due to the bulky steric effect. The molecular structure of 5 has been determined by X-ray diffraction. The relationship between structures of catalysts and catalytic activities were discussed.