Intramolecular Electron Transfer and Dehalogenation of Nitroaromatic Anion Radicals¹

A series of nitroaromatic compounds, containing Cl, Br, or tosyl groups at various positions, were synthesized and studied by pulse radiolysis in aqueous alcohol solutions. One-electron reduction of the compounds produces the anion radicals which then undergo an intramolecular electron transfer and eliminate X^- (C1^-, Br^-, or TsO^-). The rates of X^- elimination vary over six orders of magnitude and are affected by the C-X bond dissociation energies, the size and nature of the group bridging the X with the π system, and the relative positions of these groups. Intramolecular electron transfer through space is also demonstrated.