Charge Transfer and OH Vibrational Frequency Red Shifts in Nitrate-Water Clusters

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• 作者：Sai G. Ramesh ; Suyong Re ; James T. Hynes
• 刊名：Journal of Physical Chemistry A
• 出版年：2008
• 出版时间：April 17, 2008
• 年：2008
• 卷：112
• 期：15
• 页码：3391 - 3398
• 全文大小：160K
• 年卷期：v.112,no.15(April 17, 2008)
• ISSN：1520-5215

文摘

A theoretical study of charge transfer (CT) characteristics in nitrate (Nrnals/jpcafh/112/i15/eqn/jp0761012e10001.gif">) anion-water complexes ispresented, together with those for the halides, F^-, Cl^-, and Br^-, for comparison. The relation between thevibrational frequency red shifts of the hydrogen (H)-bonded OH stretches and CT from the anion to the watermolecule, established in previous work for the one-water complexes of the halides, is studied for both theone- and six-water nitrate complexes and is extended to the six-water case for the halides. In Nrnals/jpcafh/112/i15/eqn/jp0761012e10002.gif">·H₂O, thewater molecule receives about as much charge as that in Br^-·H₂O. In a result consistent with aqueous phaseinfrared experiments [Bergström, P. A.; Lindgren, J.; Kristiansson, O. J. Phys. Chem. 1991, 95, 8575-8580],the CT and OH red shift in Nrnals/jpcafh/112/i15/eqn/jp0761012e10003.gif">·6H₂O are found to be smaller than those for all of the six-water halidecomplexes, despite the presence of three H-bonding sites. The inability of the nitrate anion to effect substantialCT lies in the preservation of the -system being energetically favored over charge localization and enhancementof the strengths of the multiple H-bonds.