Temperature dependence of the rate constants for reaction of dihalide and azide radicals with inorganic reductants

L. C.T. Shoute, Z. B. Alfassi, P. Neta, R. E. Huie

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20 Scopus citations

Abstract

Rate constants for several reactions of inorganic radicals with inorganic reductants in aqueous solutions have been measured by pulse radiolysis as a function of temperature, generally between 5 and 75°C. The reactions studied were of the dihalide radicals, Cl2•-, Br2•-, and I2•-, the (SCN)2•- radical, and the neutral radical N3, reacting with the substitution-inert metal complexes, Fe(CN)64-, Mo(CN)84-, and W(CN)84-, and with the anions SO32-, HSO3-, NO2-, and ClO2-. The rate constants measured were in the range of 106 to 5 × 109 M-1 s-1 and the calculated Arrhenius activation energies ranged from 5 to 35 kJ mol-1. The preexponential factors also varied considerably, with log A ranging from 8.9 to 13.1. The temperature dependence of the reaction rate constant is correlated to the reaction exothermicity for the metal complexes, which apparently react by outer-sphere electron transfer. The simple anions, however, have lower activation energies, which do not correlate well with the exothermicities, suggesting that these anions probably react by an inner-sphere mechanism.

Original languageEnglish
Pages (from-to)3238-3242
Number of pages5
JournalJournal of Physical Chemistry
Volume95
Issue number8
DOIs
StatePublished - 1 Jan 1991

ASJC Scopus subject areas

  • Engineering (all)
  • Physical and Theoretical Chemistry

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