One-electron reduction of aqueous nitric oxide: a mechanistic revisionстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 27 марта 2017 г.
Аннотация:
View at Publisher|
Export
| Download | Add to List | More...
Inorganic Chemistry
Volume 44, Issue 15, 25 July 2005, Pages 5212-5221
One-electron reduction of aqueous nitric oxide: A mechanistic revision (Article)
Lymar, S.V.a ,
Shafirovich, V.b,
Poskrebyshev, G.A.ac
a Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, United States
b Chemistry Department, Radiation and Solid State Laboratory, New York University, New York, NY 10003, United States
c Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences, Moscow 117829, Russian Federation
View additional affiliations
View references (40)
Abstract
The pulse radiolysis of aqueous NO has been reinvestigated, the variances with the prior studies are discussed, and a mechanistic revision is suggested. Both the hydrated electron and the hydrogen atom reduce NO to yield the ground-state triplet 3NO- and singlet 1HNO, respectively, which further react with NO to produce the N2O 2 - radical, albeit with the very different specific rates, k(3NO- + NO) = (3.0 ± 0.8) × 109 and k(1HNO + NO) = (5.8 ± 0.2) × 106 M -1 s-1. These reactions occur much more rapidly than the spin-forbidden acid-base equilibration of 3NO- and 1HNO under all experimentally accessible conditions. As a result, 3NO- and 1HNO give rise to two reaction pathways that are well separated in time but lead to the same intermediates and products. The N2O2 - radical extremely rapidly acquires another NO, k(N2O2 - + NO) = (5.4 ± 1.4) × 109 M-1 s-1, producing the closed-shell N3O3 - anion, which unimolecularly decays to the final N2O + NO2 - products with a rate constant of ∼300 s-1. Contrary to the previous belief, N2O2 - is stable with respect to NO elimination, and so is N3O3 -. The optical spectra of all intermediates have also been reevaluated. The only intermediate whose spectrum can be cleanly observed in the pulse radiolysis experiments is the N3O3 - anion (λmax = 380 nm, εmax = 3.76 × 103 M-1 cm -1). The spectra previously assigned to the NO- anion and to the N2O2 - radical are due, in fact, to a mixture of species (mainly N2O2 - and N 3O3 -) and to the N3O 3 - anion, respectively. Spectral and kinetic evidence suggests that the same reactions occur when 3NO- and 1HNO are generated by photolysis of the monoprotonated anion of Angeli's salt, HN2O3 -, in NO-containing solutions.