Dyotropic rearrangement of bridgehead substituents in closed dithienylethenes; conjugated verses non-conjugated analogues

Type I dyotropic rearrangement reactions of halogen and methyl substituents at the bridgehead position of diarylethenes and dihydroarylethenes have been studied through density functional theory at B3LYP/6-31+G(d) level. The calculations have been performed to explore the dyotropic rearrangement as a possible factor for the elusive nature of halogenated dithienylethenes (closed). The dyotropic rearrangement process in closed dithienylethenes is then compared with the dihydro analogues. Moreover, the effect of hetero atom and conjugation is also explored through quantum mechanical calculations.