Rate constants and activation parameters for outer-sphere electron-transfer reactions and comparisions with the predictions of Marcus theory
Rate constants at 25/sup 0/C and activation parameters are reported for several outer-sphere electron-transfer reactions. The oxidants studied include Ru(NH/sub 3/)/sub 6//sup 3 +/, Ru(NH/sub 3/)/sub 5/py/sup 3 +/, Co(phen)/sub 3//sup 3 +/, and Ru(NH/sub 3/)/sub 4/(bpy)/sup 3 +/ while the reductants include Eu/sub aq//sup 2 +/, V/sup 2 +//sub aq/, Ru(NH/sub 3/)/sub 6//sup 2 +/, and Ru(NH/sub 3/)/sub 5/py/sup 2 +/. From Marcus calculations using cross-reaction data, self-exchange rates for the Eu/sup 2 +//sub aq//Eu/sup 3 +//sub aq/ and Cr(bpy)/sub 3//sup 2 +//Cr(bpy)/sub 3//sup 3 +/ couples are estimated as 10/sup -5/ to 10/sup -4/ M/sup -1/ s/sup -1/ and 10/sup 7/ to 10/sup 9/ M/sup -1/ s/sup -1/, respectively, at 25/sup 0/C and ..mu.. = 1.0 M. The data for outer-sphere electron transfer reactions between 2+ and 3+ charged ions with known self-exchange rates are reviewed. Marcus theory is found to be reasonably successful in predicting the rate constants for the cross-reactions. In general, however, observed rate constants are smaller than the calculated values. The assumptions of the Marcus model are reviewed in an effort to determine where the model fails.
- Research Organization:
- Brookhaven National Lab., Upton, NY
- OSTI ID:
- 7295161
- Journal Information:
- J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 99:17; ISSN JACSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ACTIVATION ENERGY
CHARGE EXCHANGE
CHEMICAL REACTION KINETICS
ENERGY
KINETICS
OXIDIZERS
REACTION KINETICS
REDUCING AGENTS