Synergy between Two Metal Catalysts: A Highly Active Silica-Supported Bimetallic W/Zr Catalyst for Metathesis of n-Decane

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• 作者：Manoja K. Samantaray ; Raju Dey ; Santosh Kavitake ; Edy Abou-Hamad ; Anissa Bendjeriou-Sedjerari ; Ali Hamieh ; Jean-Marie Basset
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：July 13, 2016
• 年：2016
• 卷：138
• 期：27
• 页码：8595-8602
• 全文大小：496K
• 年卷期：0
• ISSN：1520-5126

文摘

A well-defined, silica-supported bimetallic precatalyst [≡Si–O–W(Me)₅≡Si–O–Zr(Np)₃] (4) has been synthesized for the first time by successively grafting two organometallic complexes [W(Me)₆ (1) followed by ZrNp₄ (2)] on a single silica support. Surprisingly, multiple-quantum NMR characterization demonstrates that W and Zr species are in close proximity to each other. Hydrogenation of this bimetallic catalyst at room temperature showed the easy formation of zirconium hydride, probably facilitated by tungsten hydride which was formed at this temperature. This bimetallic W/Zr hydride precatalyst proved to be more efficient (TON = 1436) than the monometallic W hydride (TON = 650) in the metathesis of n-decane at 150 °C. This synergy between Zr and W suggests that the slow step of alkane metathesis is the C–H bond activation that occurs on Zr. The produced olefin resulting from a β-H elimination undergoes easy metathesis on W.