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Title: Mechanistic insight into peroxydisulfate reactivity: Oxidation of the cis,cis-[Ru(bpy)2(OH2)]2O4+ "Blue Dimmer"

One-electron oxidation of the μ-oxo dimer (cis,cis-[RuIII(bpy)2(OH2)]2O4+, {3,3}) to {3,4} by S2O82- can be described by three concurrent reaction pathways corresponding to the three protic forms of {3,3}. Free energy correlations of the rate constants, transient species dynamics determined by pulse radiolysis, and medium and temperature dependencies of the alkaline pathway all suggest that the rate determining step in these reactions is a strongly non-adiabatic dissociative electron transfer within a precursor ion pair leading to the {3,4}|SO42-|SO4•- ion triple. As deduced from the SO4•- scavenging experiments with 2-propanol, the SO4•- radical then either oxidizes {3,4} to {4,4} within the ion triple, effecting a net two-electron oxidation of {3,3}, or escapes in solution with ~25 % probability to react with additional {3,3} and {3,4}, that is, effecting sequential one-electron oxidations. The reaction model presented also invokes rapid {3,3} + {4,4} → 2{3,4} comproportionation, for which kcom ~5×107 M-1 s-1 was independently measured. The model provides an explanation for the observation that despite favorable energetics, no oxidation beyond the {3,4} state was detected. As a result, the indiscriminate nature of oxidation by SO4•- indicates that its fate must be quantitatively determined when using S2O82- as an oxidant
Authors:
 [1] ;  [2] ;  [3]
  1. Washington State Univ., Pullman, WA (United States)
  2. Oregon State Univ., Corvallis, OR (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
OSTI Identifier:
1214523
Report Number(s):
BNL--108319-2015-JA
Journal ID: ISSN 1520-6106; R&D Project: CO004; KC0304030
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Journal of Physical Chemistry. B, Condensed Matter, Materials, Surfaces, Interfaces and Biophysical Chemistry
Additional Journal Information:
Journal Volume: 119; Journal Issue: 24; Journal ID: ISSN 1520-6106
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY