Electrochemical evidence for the existence of three stable oxidation states for heterocycles of the type XC₆H₄CN₂E₂ (E = S, Se). X‐ray crystal structure of the dimer with X = Cl, E = S

Abstract

Abstract The preparation and isolation in the solid state of five aryl 1,2,3,5‐dithia‐ and diselenadiazolyls is reported. The structure of the dimer of 4‐ClC 6 H 4 CN 2 S 2 in the solid state was obtained: monoclinic, C2/c with Z = 8, a = 20.982(10), b = 10.058(3), c = 15.867(6) Å, β = 93.34(4)°, R = 0.066, R w = 0.053 for 1 099 data. Cyclic voltammetry shows reversible oxidation to a 6π cation for all 10 compounds in both CH 2 Cl 2 and CH 3 CN; reversible reduction to an 8π anion is observed in CH 2 Cl 2 for all except X = CF 3 , E = S. The reductions are only quasi‐reversible in CH 3 CN for E = Se. The oxidation process is independent of chalcogen type; the reduction process is found to be about 0.2 V more negative for E = S vs E = Se.