The radical anions of the four isomeric furan and thiophene thioaldehydes have been obtained by photolysis, in an alkaline medium, of the corresponding thiols in the presence of di-tert-butyl peroxide. The same reaction also yields the four corresponding aldehyde radical anions, starting from the appropriate alcohols. The ESR spectra show that in most caaes the two rotational conformers (E and Z) are present at the equilibrium. By means of ...