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

Abstract

AbstractNew 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 × 105 g‐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 × 106 g‐PE/mol‐Zr·h; 1‐hexene content, 3.65%). © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4901–4913, 2007