Thermal-electron transfer in crystalline complexes with hydrogen bonding

Abstract

The complexes of p-benzoquinone and chlorobenzoquinone with hydroquinone, chlorohydroquinone and p-phenylenediamine in solution and solid state have been investigated. The large shift of the charge-transfer bands in solid complexes (5000–11 000 cm^–1) in comparison with solution is due to the occurrence of chain-like hydrogen bonding. Two BQ/ChHQ complexes, differing in charge-transfer energy and degree of hydrogen bonding, are observed. The elementary redox conversions are assumed to proceed through excited states of the complexes, the activation energies of the reactions being close to the charge-transfer energies.