Gas-Phase Models for Catalysis: Alkane Activation and Olefin Epoxidation by the Triatomic Cation Ag2O+

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• 作者：Jana Roithová ; Detlef Schr&ouml ; der
• 刊名：Journal of the American Chemical Society
• 出版年：2007
• 出版时间：December 12, 2007
• 年：2007
• 卷：129
• 期：49
• 页码：15311 - 15318
• 全文大小：283K
• 年卷期：v.129,no.49(December 12, 2007)
• ISSN：1520-5126

文摘

Electrospray ionization of aqueous silver nitrate is used for the preparation of the disilver-oxidecation Ag₂O⁺ in the gas phase. The mass-selected cation is capable of activating C-H bonds of simplealkanes other than methane via H-atom abstraction, i.e., Ag₂O⁺ + R-H Ag₂OH⁺ + R (R = C₂H₅, C₃H₇,C₄H₉). Clean O-atom transfer from Ag₂O⁺ is observed with ethene as a neutral reagent, whereas oxygenationand allylic C-H abstraction compete in the case of propene. The gaseous Ag₂O⁺ cation can thus be regardedas a minimalist model for the problems associated with the silver-mediated epoxidation of olefins morecomplex than ethene itself. The experimental findings are fully supported by the results of quantum chemicalstudies, thereby providing deep mechanistic insight into the reactions in the idealized gas phase, whichalso might have implications for further improvements in applied catalysis.