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From a localized H3O radical to a delocalized H 3O+⋯e- solvent-separated pair by sequential hydration

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Original languageEnglish
Pages (from-to)14003-14009
Number of pages7
JournalPhysical Chemistry Chemical Physics
Issue number31
Publication statusPublished - 21 Aug 2011
Publication typeA1 Journal article-refereed


The impact of microhydration on the electronic structure and reactivity of the H3O moiety is investigated by ab initio calculations. In the gas phase, H3O is a radical with spin density localized on its hydrogen end, which is only kinetically stable and readily decomposes into a water molecule and a hydrogen atom. When solvated by a single water molecule, H 3O preserves to a large extent its radical character, however, two water molecules are already capable to shift most of the spin density to the solvent. With three solvating water molecules this shift is practically completed and the system is best described as a solvent-separated pair of a hydronium cation and a hydrated electron. The electronic structure of this system and its proton transfer reactivity leading to formation of a hydrogen atom already resemble those of a proton-electron pair in bulk water.