Synthesis, structure, and catalytic properties of ansa-Zirconocenes, Me 2X(Cp)(RInd) ZrCl 2 (X = C, Si; R = 2- p- or 3- p-tolyl)

Abstract

ansa-Zirconocenes, Me 2X(Cp)(3-Tollnd)ZrCl 2 [X = C ( 7), Si ( 8); Cp = η 5-C 5H 5; Tol = p-C 6H 4CH 3] and Me 2Si(Cp)(2-TolInd)ZrCl 2 ( 9), have been prepared by the reactions of ZrCl 4 with the corresponding dilithiated ligands in diethyl ether at −78°C. The molecular structure of complex 9 has been determined by a single crystal X-ray diffraction study. Propylene polymerization has been studied for complexes 7, 8 and 9 in the presence of methylaluminoxane (MAO). Complex 9 reveals the highest catalytic activity of 1570kg PP/(mol Zr h atm) and the highest molecular weight of 1.2 × 10 6 among the three catalysts. Complex 9 produces atactic polypropylene (PP), whereas 7 and 8 afford PP with a weak syndiotacticity at low temperature.