New O- and N-bonded zirconocene complexes and their catalytic properties in ethylene polymerization.: X-ray crystal structure of (C5H5)2Zr{2,6-OC6H3(CH3)2}2, (C5H5)2Zr{2,4,6-OC6H2(CH3)3}2 and (C5H5)2Zr(CH3){CH(NC6H5)2}

A series of zirconocene complexes of formula Cp2ZrMe2-nLn where Cp = C5H5-, Me = methyl, L = pyrazolyl, bis(N,N'-phenylformamidinato), or substituted aryloxide and n = 1,2, were synthesized by reaction of Cp2ZrCl2 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 demonstrate appreciable activity for ethylene polymerization when used as cocatalysts with methylaluminoxane and dimethylanilinium tetrafluorophenylborate. (C) 1998 Elsevier Science S.A. All rights reserved.