NEW O-BONDED AND N-BONDED ZIRCONOCENE COMPLEXES AND THEIR CATALYTIC PROPERTIES IN ETHYLENE POLYMERIZATION - X-RAY CRYSTAL-STRUCTURE OF (C5H5)(2)ZR(2,6-OC6H3(CH3)(2))(2), (C5H5)(2)ZR(2,4,6-OC6H2(CH3)(3))(2) AND(C5H5)(2)ZR(CH3)(CH(NC6H5)(2))

A series of zirconocene complexes of formula Cp2ZrMe2-nLn where Cp = C 5H5-, Me = methyl, L = pyrazolyl, bis(N,N'-phenylformamidinato), or su bstituted aryloxide and n = 1,2, were synthesized by reaction of Cp2Zr Cl2 and Cp2ZrMe2 with Lit or HL, respectively. The structures of Cp2Zr (2,6-OC6H3Me2)(2), Cp2Zr(2,4,6-OC6H2Me3)(2) and Cp2ZrMe{CH(NC6H5)(2)} were determined by single crystal X-ray diffraction. The complexes dem onstrate appreciable activity for ethylene polymerization when used as cocatalysts with methylaluminoxane and dimethylanilinium tetrafluorop henylborate. (C) 1998 Elsevier Science S.A. All rights reserved.