Thermodynamics of Electron Transfer from the Cyclooctatetraene Anion Radical to a Series of Substituted Cyclooctatetraenes and Annulene

Article abstract of DOI:10.1021/j150604a015

Electron spin resonance has been utilized to measure the free energy, enthalpy, and entropy changes for the electron transfer from the anion radical of cyclooctatetraene (COT) to several substituted cyclooctatetraenes (XCOT) and to <16>annulene in hexamethylphosphoramide (HMPA), where the anion radical are free from ion association effects.There is a correlation between the enthalpy of the electron transfer (ΔH⁰ for COT^-. + XCOT <=> COT + XCOT^-) and the magnitude of the splitting of the degeneracy of the nonbonding molecular orbitals due to the presence of the substituent (Δε).However, the fact that ΔH⁰ for the electron transfer is much more sensitive to the presence of the substituent than is Δε leads us to conclude that Δε is greatly effected by solvation.