CC Bond Cleavage on Neutral VO3(V2O5)n Clusters

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• 作者：Feng Dong ; Scott Heinbuch ; Yan Xie ; Elliot R. Bernstein ; Jorge J. Rocca ; Zhe-Chen Wang ; Xun-Lei Ding ; Sheng-Gui He
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：January 28, 2009
• 年：2009
• 卷：131
• 期：3
• 页码：1057-1066
• 全文大小：432K
• 年卷期：v.131,no.3(January 28, 2009)
• ISSN：1520-5126

文摘

The reactions of neutral vanadium oxide clusters with alkenes (ethylene, propylene, 1-butene, and 1,3-butadiene) are investigated by experiments and density function theory (DFT) calculations. Single photon ionization through extreme ultraviolet radiation (EUV, 46.9 nm, 26.5 eV) is used to detect neutral cluster distributions and reaction products. In the experiments, we observe products (V₂O₅)_nVO₂CH₂, (V₂O₅)_nVO₂C₂H₄, (V₂O₅)_nVO₂C₃H₄, and (V₂O₅)_nVO₂C₃H₆, for neural V_mO_n clusters in reactions with C₂H₄, C₃H₆, C₄H₆, and C₄H₈, respectively. The observation of these products indicates that the CC bonds of alkenes can be broken on neutral oxygen rich vanadium oxide clusters with the general structure VO₃(V₂O₅)_n=0,1,2.... DFT calculations demonstrate that the reaction VO₃ + C₃H₆ → VO₂C₂H₄ + H₂CO is thermodynamically favorable and overall barrierless at room temperature. They also provide a mechanistic explanation for the general reaction in which the CC double bond of alkenes is broken on VO₃(V₂O₅)_n=0,1,2... clusters. A catalytic cycle for alkene oxidation on vanadium oxide is suggested based on our experimental and theoretical investigations. The reactions of V_mO_n with C₆H₆ and C₂F₄ are also investigated by experiments. The products VO₂(V₂O₅)_nC₆H₄ are observed for dehydration reactions between V_mO_n clusters and C₆H₆. No product is detected for V_mO_n clusters reacting with C₂F₄. The mechanisms of the reactions between VO₃ and C₂F₄/C₆H₆ are also investigated by calculations at the B3LYP/TZVP level.