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