Intracluster ion-molecule reactions between V⁺ and methyl acetate or ethyl acetate clusters

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• 作者：Dababrata Paul^a ; Kiryong Hong^a ; Tae Kyu Kim^a ; ^{tkkim@pusan.ac.kr} ; Jun-Sik Oh^b ; Kwang-Woo Jung^b ; ^{kwjung@wku.ac.kr}
• 关键词：Ion&ndash ; molecule reaction ; Vanadium ; Heterocluster ; Alkyl acetate
• 刊名：International Journal of Mass Spectrometry
• 出版年：2012
• 期刊代码：43_13873806
• 类别：ch
• 出版时间：1 April, 2012
• 卷：315
• 期：Complete
• 页码：15-21
• 文件大小：719 K

摘要

Intracluster ion-molecule reactions of V⁺(CH₃COOR)_n (R = CH₃, C₂H₅, C₂D₅) complexes produced by the mixing of laser-vaporized plasmas and pulsed supersonic beams were investigated by reflectron time-of-flight mass spectrometry. The mass spectra indicated the presence of a major sequence of cluster ions with the formula V⁺(CH₃COO)(CH₃COOR)_n. This sequence is attributed to the insertion of V⁺ into the CO bond of CH₃COOR within the heteroclusters, followed by alkyl radical (R) elimination. The observation of V⁺(OR) and V⁺(CH₃)(OR) ions is interpreted as arising from the insertion of V⁺ into the C(O)O bond of the ester group, followed by CH₃CO and CO elimination, respectively. In addition, the VO⁺ ion is present throughout the mass spectra, indicating that insertion of V⁺ into the CO bond of CH₃COOR also occurs. Within the stabilizing environs of a heterocluster, sequential insertions of VO⁺ ions into a second molecule produced VO⁺(CH₃COO)(CH₃COOR)_n and VO⁺(CH₃)(OR)(CH₃COOR)_n heteroclusters via reaction pathways similar to those of the V⁺ ion. The results of isotope-labeling experiments suggest that the reaction pathway for formation of V⁺(CH₃COOH)(CH₃COOC₂H₅)_n involves V⁺ insertion into the CO bond of ethyl acetate, followed by 尾-H atom transfer from the ethyl group. Density functional theory calculations were carried out to model the structures and binding energies of both the association complexes and the relevant reaction products. The reaction pathways and energetics of each product channel are presented.