SYNTHESIS AND PROPERTIES OF DIHEXYLBITHIENOQUINONOID DERIVATIVES WITHHEAD-TO-HEAD, HEAD-TO-TAIL, AND TAIL-TO-TAIL ORIENTATIONS

thienylidene-5,5'-diylidene)bis(propanedinitrile)s (dihexylbithienoqui nonoid derivatives), in which two 3-hexylthiophene moieties are connec ted with head-to-tail (HT) and tail-to-tail (TT) orientations, were sy nthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case fo r the head-to-head (HH) orientational isomer. On the other hand, Tr is omer exhibited a peculiar feature in solution, affording an equilibriu m mixture of two geometrical isomers. Electronic and electrochemical p roperties of these bithienoquinonoids were studied and compared with t hose of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properti es. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electro n transfer processes via stable radical anions to the corresponding di anions.