Influence of Alkyl Substituents on the Polymerization Behavior of Asymmetric Ethylene-Bridged Zirconocene Catalysts

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• 作者：Emma J. Thomas ; James C. W. Chien ; and Marvin D. Rausch
• 刊名：Organometallics
• 出版年：1999
• 出版时间：April 12, 1999
• 年：1999
• 卷：18
• 期：8
• 页码：1439 - 1443
• 全文大小：55K
• 年卷期：v.18,no.8(April 12, 1999)
• ISSN：1520-6041

文摘

A series of substituted indenyl-fluorenyl asymmetric ethylene-bridged ligands have beenprepared from the reaction of 1-(9-fluorenyl)-2-bromoethane and the lithium salt of thedesired indenyl moiety. The ligands have been converted to the corresponding substitutedasymmetric ethylene-bridged metallocenes (M = Zr, Hf). These metallocenes have beenevaluated as catalyst precursors for the polymerization of ethylene and propylene. Theinfluence of substitution on the selectivity of the propylene polymerization has been studied.The metallocene [1-(9-fluorenyl)-2-(2,4,7-trimethyl-1-indenyl)ethane]zirconium dichloride wasfound to produce highly isotactic polypropylene with an [mmmm] value of 86%.