A correlation between half-wave and ionization potentials for indoles and indolizines

Abstract

Half-wave oxidation potentials (E_1/2), in acetonitrile at a platinum electrode, and gas-phase ionization potentials (P) have been measured for a number of indole and indolizine derivatives, variously substituted on the five-membered ring. Except for a few compounds, a linear correlation of P vs. E_1/2 was found. Deviations from linearity are discussed in terms of conformation differences between the two phases and P value uncertainties in those cases where the vibrational fine structure was resolved.