Correlations between Localization Energies and Polarographic Half-Wave Potentials of Aromatic Hydrocarbons

Abstract

Basu and Bhattacharya¹ recently claimed to have established a linear correlation between para-localization energies and polarographic half-wave potentials for some polynuclear hydrocarbons. Objections to their work have been raised by Pullman² and Fernandez-Alonso and Domingo³, who criticize the values of the localization energies selected by Basu and Bhattacharya. All these authors use the polarographic data of Wawzonek and Laitinen⁴, but all of them appear to have misunderstood the latter workers' statement that polarographic reduction consists of a two-electron addition process. It is true that the overall reaction consists of the addition of two electrons. But it is clear from the work of Wawzonek and Laitinen themselves, as well as from that of later authors^5–7, that the addition takes place by two one-electron steps. The least negative half-wave potential might therefore be expected to characterize the energy required to add one electron to the aromatic system, but could scarcely be related to the para-localization energy, which is a measure of the ease of addition to two positions in a hydrocarbon simultaneously⁸.