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Group 4 Dimethylsilylenebisamido Complexes Bearing the 6-[2-(Diethylboryl)phenyl]pyrid-2-yl Motif: Synthesis and Use in Tandem Ring-Opening Metathesis/Vinyl-Insertion Copolymerization of Cyclic Olefins with Ethylene

Authors

  • Dr. Yuanlin Zou,

    1. Leibniz-Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig (Germany)
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  • Dr. Dongren Wang,

    1. Institut für Polymerchemie, Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)
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  • Dr. Klaus Wurst,

    1. Institut für Allgemeine, Anorganische und Theoretische Chemie, Universität Innsbruck, Innrain 52a, 6020 Innsbruck (Austria)
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  • Christa Kühnel,

    1. Leibniz-Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig (Germany)
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  • Ingrid Reinhardt,

    1. Leibniz-Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig (Germany)
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  • Dr. Ulrich Decker,

    1. Leibniz-Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig (Germany)
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  • Venkatanavarana Gurram,

    1. Institut für Polymerchemie, Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)
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  • Dr. Sebnem Camadanli,

    1. Leibniz-Institut für Oberflächenmodifizierung, Permoserstrasse 15, 04318 Leipzig (Germany)
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  • Prof. Dr. Michael R. Buchmeiser

    Corresponding author
    1. Institut für Polymerchemie, Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)
    2. Institut für Textilchemie und Chemiefasern (ITCF), Körschtalstr. 26, 73770 Denkendorf (Germany)
    • Institut für Polymerchemie, Lehrstuhl für Makromolekulare Stoffe und Faserchemie, Universität Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart (Germany)
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Abstract

Two novel ZrIV- and HfIV-based bisamido complexes bearing the 6-[2-(diethylboryl)phenyl]pyrid-2-yl motif, that is, [ZrCl2{Me2Si(DbppN)2}(thf)] (9) and [HfCl2{Me2Si(DbppN)2}(thf)2] (10) (DbppN=6-[2-(diethylboryl)phenyl]pyridine-2-amido) have been prepared. Their reactivities have been compared with that of a model precatalyst that does not bear the aminoborane motif. Upon activation with methylalumoxane, precatalysts 9 and 10 are active in the homopolymerization of ethylene (E) yielding high-density polyethylene (HDPE). In the copolymerization of E with cyclopentene (CPE), for example by the action of 9, the presence of CPE resulted in a dramatic increase in the polymerization activity of E, while CPE incorporation remained close to or at zero. In the vinyl-insertion copolymerization of norborn-2-ene (NBE) with E by the action of 9, statistical cyclic olefin copolymers of these two monomers were obtained. At higher NBE concentrations, however, 9 gave rise to reversible ring-opening metathesis (ROMP)/vinyl-insertion polymerization (VIP) of NBE with E, resulting in the formation of multi-block copolymers of the general formula poly(NBE)ROMP-co-poly(NBE)VIP-co-poly(E). This particular feature of precatalyst 9, that is, the ability to induce a reversible α-H elimination/α-H addition reaction, is attributed to the unique role of the 6-[2-(diethylboryl)phenyl]pyrid-2-yl ligand. Accordingly, a model precatalyst lacking this ligand does not have the ability to induce α-H elimination/α-H addition reactions. The different 11B NMR shifts of various diethylborylphenylpyrid-2-ylamines and -amides permit a ranking of the strengths of the B[BOND]N bonds in these compounds. This strength of the B[BOND]N bond is correlated with the propensity of 9/MAO to produce poly(NBE)ROMP-co-poly(NBE)VIP-co-poly(E) at different temperatures.

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