Decomposition of Ruthenium Olefin Metathesis Catalysts

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• 作者：Soon Hyeok Hong ; Anna G. Wenzel ; Tina T. Salguero ; Michael W. Day ; Robert H. Grubbs
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：June 27, 2007
• 年：2007
• 卷：129
• 期：25
• 页码：7961 - 7968
• 全文大小：380K
• 年卷期：v.129,no.25(June 27, 2007)
• ISSN：1520-5126

文摘

The decomposition of a series of ruthenium metathesis catalysts has been examined usingmethylidene species as model complexes. All of the phosphine-containing methylidene complexesdecomposed to generate methylphosphonium salts, and their decomposition routes followed first-orderkinetics. The formation of these salts in high conversion, coupled with the observed kinetic behavior forthis reaction, suggests that the major decomposition pathway involves nucleophilic attack of a dissociatedphosphine on the methylidene carbon. This mechanism also is consistent with decomposition observed inthe presence of ethylene as a model olefin substrate. The decomposition of phosphine-free catalyst(H₂IMes)(Cl)₂Ru=CH(2-C₆H₄-O-i-Pr) (H₂IMes = 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) with ethylenewas found to generate unidentified ruthenium hydride species. The novel ruthenium complex (H₂IMes)(pyridine)₃(Cl)₂Ru, which was generated during the synthetic attempts to prepare the highly unstable pyridine-based methylidene complex (H₂IMes)(pyridine)₂(Cl)₂Ru=CH₂, is also reported.