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Title: Water network-mediated, electron-induced proton transfer in [C{sub 5}H{sub 5}N ⋅ (H{sub 2}O){sub n}]{sup −} clusters

The role of proton-assisted charge accommodation in electron capture by a heterocyclic electron scavenger is investigated through theoretical analysis of the vibrational spectra of cold, gas phase [Py ⋅ (H{sub 2}O){sub n=3−5}]{sup −} clusters. These radical anions are formed when an excess electron is attached to water clusters containing a single pyridine (Py) molecule in a supersonic jet ion source. Under these conditions, the cluster ion distribution starts promptly at n = 3, and the photoelectron spectra, combined with vibrational predissociation spectra of the Ar-tagged anions, establish that for n > 3, these species are best described as hydrated hydroxide ions with the neutral pyridinium radical, PyH{sup (0)}, occupying one of the primary solvation sites of the OH{sup −}. The n = 3 cluster appears to be a special case where charge localization on Py and hydroxide is nearly isoenergetic, and the nature of this species is explored with ab initio molecular dynamics calculations of the trajectories that start from metastable arrangements of the anion based on a diffuse, essentially dipole-bound electron. These calculations indicate that the reaction proceeds via a relatively slow rearrangement of the water network to create a favorable hydration configuration around the water molecule that eventuallymore » donates a proton to the Py nitrogen atom to yield the product hydroxide ion. The correlation between the degree of excess charge localization and the evolving shape of the water network revealed by this approach thus provides a microscopic picture of the “solvent coordinate” at the heart of a prototypical proton-coupled electron transfer reaction.« less
Authors:
; ;  [1] ;  [1] ;  [2] ; ;  [3] ; ; ;  [4]
  1. Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520 (United States)
  2. (United States)
  3. Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, Pennsylvania 15260 (United States)
  4. Department of Chemistry and Biochemistry, University of Mississippi, University, Mississippi 38677 (United States)
Publication Date:
OSTI Identifier:
22489707
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 14; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANIONS; DIPOLES; ELECTRON CAPTURE; ELECTRON TRANSFER; ELECTRONS; HYDRATION; HYDROXIDES; ION PAIRS; ION SOURCES; MOLECULAR DYNAMICS METHOD; MOLECULES; NITROGEN; PHOTOELECTRON SPECTROSCOPY; PROTONS; PYRIDINE; SOLVENTS; SPECTRA; WATER