Ethene polymerization with mixed-ring metallocene catalysts, Cp ' Cp '' MCl2, M = Ti and Zr

Mixed-ring metallocenes Cp'Cp'MCl2 (Cp' and Cp" = cyclopentadienyl and its substituted derivatives; M = Ti and Zr) have been prepared by reacting Cp'M Cl3 with the Cp' anion salt, in which the Cp'-M bond is stronger than the C p"-M bond. Ethene has been polymerized with these complexes in the presence of methyl aluminoxane (MAO) as co-catalyst. The catalytic properties of ti tanocenes were influenced mainly by the steric effects of cyclopentadienyl ring substituents. Both steric and electronic effects of substituents influ enced the catalytic properties of zirconocenes.