Novel C1 symmetric zirconocenes containing substituted indenyl moieties for the stereoregular polymerization of propylene

Abstract The synthesis and polymerization behavior of four new asymmetric ansa -metallocenes containing a fluorenyl moiety and a substituted indenyl moiety is reported. The zirconocenes diphenylsilylene-(η 5 -9-fluorenyl)-[η 5 -1-(3- t -butyl)indenyl]-zirconium dichloride ( 4 ), dimethylsilylene-(η 5 -9-fluorenyl)-[η 5 -1-(3- t -butyl)indenyl]-zirconium dichloride ( 5 ), ethylene-1-(η 5 -9-fluorenyl)-2-[η 5 -1-(3- t -butyl)indenyl]-zirconium dichloride ( 6 ), and diphenylsilylene-(η 5 -9-fluorenyl)-[η 5 -1-(2-methyl-4-phenyl)indenyl]-zirconium dichloride ( 8 ) were all found to be highly active for the polymerization of both ethylene and propylene when activated with excess methylaluminoxane. Compound 8 was found to produce highly isotactic polypropylene with an [mmmm] value of 83%.