二核メタロセン錯体(η^5:η^5-Fulvalene)[η^5-(C_5H_5)Zr(μ-Cl)]_2を用いたエチレン重合

概要

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A dinuclear zirconium complex, (η^5:η^5-Fulvalene)[(η^5-C_5H_5)Zr(μ-Cl)]_2 (2), was synthesized from Cp_2ZrCl_2 (Cp=η^5-C_5H_5) (1) by a reported procedure. An alternative route to synthesize 2 was achieved using BuLi as the reducing reagent of the zirconium atoms. Polymerization of ethylene and copolymerization of ethylene and 1-hexene were catalyzed by 2 in the presence of methylaluminoxane (MAO) as the cocatalyst. Catalytic activities dependent on the reaction temperatures and average molecular weight and dispersity of the polymers obtained were compared with those experimentally available with 1 under the same conditions. Polymerization of ethylene with several dinuclear zirconium complexes, of which metal centers were tetravalent zirconium, were reported in the literature; the results were different in average molecular weight and dispersity of the polymers from those catalyzed by 2. Mechanistic consideration of these results focussed on the role of the dinuclear structure and the oxidation state [Zr(III)] was carried out.
1999-07-08