The Influence of Specific Reactant-Solvent Interactions on Intrinsic Activation Entropies for Outer-Sphere Electron Transfer Reactions.
PURDUE UNIV LAFAYETTE IN DEPT OF CHEMISTRY
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The physical basis of the solvent contribution to the intrinsic activation entropy, Delta S Sub int, for outer-sphere electron-transfer reactions in homogeneous solution is examined in terms of the entropic parameters for the constituent electrochemical half reactions. A relationship for calculating Delta S Sub int is derived which takes into account specific reactant-solvent interactions for the isolated redox centers by employing electrochemical reaction entropy data. This relation yields rather larger and more structure-sensitive values of Delta S Sub int than those deduced on the basis of the usual dielectric continuum treatment. These considerations indicate that the more negative values of Delta S Sub int typically extracted from experimental kinetic data arise largely from the modification to the specific reactant-solvent interactions within the precursor complex caused by the proximity of the other redox center. Author
- Physical Chemistry