Gibbs free energies of transfer (ΔG∘ tr) for alkali metal ions and tl +

Abstract

Employing bisbiphenylchromium(I)/bisbiphenylchromium(O) as a reference redox system the polarographic behaviour of alkali metal ions and Tl + has been studied in butyrolactone, N-methylpyrrolidinone(2),N-methylthiopyrrolidinone(2), ethanol and acetonitrile. Based on the half wave potentials versus the above mentioned reference redox system, Gibbs free energies of transfer have been calculated for these solvents as well as for fourteen other solvents for which half wave potentials have been already published. Acetonitrile was chosen as a reference solvent. The difference in half wave potentials between ferrocene and bisbiphenylchromium(I) is reported for fourteen solvents. The half wave potential of the bisbiphenylchromium(I) reduction as also been measured in acetonitrile versus the Ag/0.01 molar AgClO 4 electrode in molar tetraethylammoniumperchlorate solutions in acetonitrile. Gibbs free energies of transfer based on the bisbiphenylchromiumassumption are compared with data obtained from the tetraphenylarsonium tetraphenylborate assumption in those solvents for which such data are available. The bisbiphenylchromium assumption and the effect of solvent parameters on the Gibbs free energy of transfer of alkali metal ions and Tl + are discussed.