Synthesis, structure, and catalytic properties of ansa-zirconocenes, Me2X(Cp)(RInd)ZrCl2 (X = C, Si; R = 2-p- or 3-p-tolyl)

Article abstract of DOI:10.1016/S0022-328X(96)06874-X

ansa-Zirconocenes, Me₂X(Cp)(3-TolInd)ZrCl₂ [X = C (7), Si (8); Cp = η⁵-C₅H₅; Tol = p-C₆H₄CH₃] and Me₂Si(Cp)(2-TolInd)ZrCl₂ (9), have been prepared by the reactions of ZrCl₄ 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 Zrh atm) and the highest molecular weight of 1.2 × 10⁶ among the three catalysts. Complex 9 produces atactic polypropylene (PP), whereas 7 and 8 afford PP with a weak syndiotacticity at low temperature.