Stability of the Monoelectronic Reduction Product from 1,2,5-Thiadiazole S,S-Dioxides. Electrochemical, Chemical, and Photoinduced Doping

Abstract

The accumulation of radical anions from 3,4-disubstituted 1,2,5-thiadiazole S,S-dioxides (1) in solution of organic solvents is achieved by electrochemical, chemical and photoinduced pathways. Electrolytic and chemical reduction of 1 produces the radical anions (1•–) in high molar yields (> ca. 80%). The survival of 1•– is measured for ca. three months. The stability of the reduced state depends on its structure and the composition (solvent, reducing agent, and supporting electrolyte) of the medium in which it is generated by the chemical and electrochemical routes. In solution of polar aprotic solvents, 1•– persists even in the presence of water or oxygen. Irradiation with 254 nm light generates 1•– but only in DMF solution; the proposed reaction mechanism involves the participation of the solvent. Radical anions are characterized by cyclic voltammetry, UV-Vis spectrophotometry and electron spin resonance spectroscopy. The chemical stability and the properties of 1/1•– make them suitable for the development of novel materials for technological applications.