New O- and N-bonded zirconocene complexes and their catalytic properties in ethylene polymerization. X-ray crystal structure of (C 5H 5) 2Zr{2,6-OC 6H 3(CH 3) 2} 2, (C 5H 5) 2Zr{2,4,6-OC 6H 2(CH 3) 3} 2 and (C 5H 5) 2Zr(CH 3){CH(NC 6H 5) 2}

Abstract

A series of zirconocene complexes of formula Cp 2ZrMe 2− n L n where Cp=C 5H 5 −, Me=methyl, L=pyrazolyl, bis( N, N′-phenylformamidinato), or substituted aryloxide and n=1,2, were synthesized by reaction of Cp 2ZrCl 2 and Cp 2ZrMe 2 with LiL or HL, respectively. The structures of Cp 2Zr(2,6-OC 6H 3Me 2) 2, Cp 2Zr(2,4,6-OC 6H 2Me 3) 2 and Cp 2ZrMe{CH(NC 6H 5) 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.