Structural Rearrangements and Magic Numbers in Reactions between Pyridine-Containing Water Clusters and Ammonia

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• 作者：Mauritz J. Ryding ; Kai Ruusuvuori ; Patrik U. Andersson ; Alexey S. Zatula ; Matthew J. McGrath ; Theo Kurt茅n ; Ismael K. Ortega ; Hanna Vehkam盲ki ; Einar Uggerud
• 刊名：The Journal of Physical Chemistry A
• 出版年：2012
• 出版时间：May 24, 2012
• 年：2012
• 卷：116
• 期：20
• 页码：4902-4908
• 全文大小：425K
• 年卷期：v.116,no.20(May 24, 2012)
• ISSN：1520-5215

文摘

Molecular cluster ions Hup>+up>(Hub>2ub>O)ub>nub>, Hup>+up>(pyridine)(Hub>2ub>O)ub>nub>, Hup>+up>(pyridine)ub>2ub>(Hub>2ub>O)ub>nub>, and Hup>+up>(NHub>3ub>)(pyridine)(Hub>2ub>O)ub>nub> (n = 16鈥?7) and their reactions with ammonia have been studied experimentally using a quadrupole-time-of-flight mass spectrometer. Abundance spectra, evaporation spectra, and reaction branching ratios display magic numbers for Hup>+up>(NHub>3ub>)(pyridine)(Hub>2ub>O)ub>nub> and Hup>+up>(NHub>3ub>)(pyridine)ub>2ub>(Hub>2ub>O)ub>nub> at n = 18, 20, and 27. The reactions between Hup>+up>(pyridine)ub>mub>(Hub>2ub>O)ub>nub> and ammonia all seem to involve intracluster proton transfer to ammonia, thus giving clusters of high stability as evident from the loss of several water molecules from the reacting cluster. The pattern of the observed magic numbers suggest that Hup>+up>(NHub>3ub>)(pyridine)(Hub>2ub>O)ub>nub> have structures consisting of a NHub>4ub>up>+up>(Hub>2ub>O)ub>nub> core with the pyridine molecule hydrogen-bonded to the surface of the core. This is consistent with the results of high-level ab initio calculations of small protonated pyridine/ammonia/water clusters.