Reactivity of substituted seven-membered heterocyclic sulfones: Spectroelectrochemical study and theoretical modeling

The redox behaviour of four arylidene substituted derivatives of dibenz-[b,e]-thiepin-5,5-dioxide-11-one was investigated in aprotic media by cyclic voltammetry coupled with spectral EPR and UV–vis–absorption techniques. The results point out that the predominant chemical reaction following the electron transfer (ET) is the cleavage of the C–SO2 bond (characteristic for the basic heterocycle) and not isomerization and/or coupling reactions (characteristic for the aryl vinyl sulfones). The solvent dependent semiempirical modeling performed in the frame of AMSOL programme package evidences as more probable the cleavage of the C–SO2 bond in the phenyl vinyl derivatives 1 and 2 after the second ET, and explains satisfactorily the different behaviour of compounds 3 and 4, determined by the presence of the phenolic OH group.