Synthesis of a [(π-Cyano-nacnac)Cp]zirconium Complex and Its Remote Activation for Ethylene Polymerization

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• 作者：Alan R. Cabrera ; Yanika Schneider ; Mauricio Valderrama ; Roland Frhlich ; Gerald Kehr ; Gerhard Erker ; Rene S. Rojas
• 刊名：Organometallics
• 出版年：2010
• 出版时间：November 22, 2010
• 年：2010
• 卷：29
• 期：22
• 页码：6104-6110
• 全文大小：948K
• 年卷期：v.29,no.22(November 22, 2010)
• ISSN：1520-6041

文摘

The NC-nacnacH ligand (2) was prepared by the deprotonation of the unsymmetrically N5-phenyl, N1-2,6-diisopropylphenyl substituted bis(imino) acetylacetonate nacnacH system (1) with n-butyllithium followed by cyanation with tosyl cyanide. Subsequent deprotonation (KH) gave the [NC-nacnac]K salt (3), which was transmetalated by reacting it with CpZrCl₃(dme), to yield the complex (NC-nacnac)CpZrCl₂ (5). Addition of one molar equivalent of B(C₆F₅)₃ gave [(C₆F₅)₃B-NC-nacnac]CpZrCl₂ (6). The compounds 2, 5, and 6 were characterized by X-ray diffraction. Activation of 5 with MAO gave an active homogeneous Ziegler−Natta catalyst for ethylene polymerization. The (NC-nacnac)CpZrCl₂/MAO system is ca. 7 times more active than the CN-free reference system (nacnac)CpZrCl₂ (4)/MAO. The B(C₆F₅)₃-containing system 6/MAO has an activity similar to 5/MAO but allows for much lower MAO concentration before the catalytic activity ceases.