Synthesis of double silylene‐bridged binuclear zirconium complexes and their use as catalysts for olefin polymerization

New double silylene-bridged binuclear zirconium complexes [(η5-RC5H4)ZrCl2]2[μ,μ-(SiMe2)2(η5-C5H3)2] [R = H (1), Me (2), nPr (3), iPr (4), nBu (5), allyl (6), 3-butenyl (7), benzyl (8), PhCH2CH2 (9), MeOCH2CH2 (10)] were synthesized by the reaction of (η5-RC5H4)ZrCl3·DME with [μ,μ-(SiMe2)2(η5-C5H3)2]2− (L2−) in THF, and they were all well characterized by 1H NMR, MS, IR, and EA. The binuclear structure of Complex 3 was further confirmed by X-ray diffraction, where the two zirconium centers are located trans relative to the bridging [μ,μ-(SiMe2)2(η5-C5H3)2] moiety. When activated with methylaluminoxane (MAO), this series of zirconium complexes are highly active catalysts for the polymerization of ethylene even under very low molar ratio of Al/Zr (Complex 7, 5.41 × 105g-PE/mol-Zr·h, Al/Zr = 50) and linear polyethylenes (PEs) with broad molecular weight distribution (MWD, Mw/Mn = 7.31–27.6) was obtained. The copolymerization experiments indicate that these complexes are also very efficient in the incorporation of 1-hexene into the growing PE chain in the presence of MAO (Complex 6, 3.59 × 106g-PE/mol-Zr·h; 1-hexene content, 3.65%). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4901–4913, 2007

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