BENZO-BRIDGED BIS(1,2,3-DITHIAZOLES) AND THEIR SELENIUM ANALOGS - PREPARATION, MOLECULAR AND ELECTRONIC-STRUCTURES, AND REDOX CHEMISTRY

The condensation of diaminobenzenedithiol with sulfur monochloride lea ds to the chloride salt of the radical cation of -dichlorobenzo[l,2-d: 4,5-d']bis(1,2,3-dithiazole), dichloro-[BB-123-DTA][Cl], which can be reduced to neutral dichloro-[BB-123-DTA] with triphenylantimony. A sim ilar condensation with selenium tetrachloride leads, upon reduction, t o the corresponding bis(l,2,3-thiaselenazole) dichloro-[BB-123-TSA]. T he crystal and molecular structures of both compounds have been determ ined by X-ray diffraction. Both compounds, which are formally antiarom atic 16 pi-systems, exhibit internal bond lengths consistent with a qu inoid formulation; The radical cations of both rings have been charact erized by ESR spectroscopy; for dichloro-[BB-123-DTA](+) g = 2.0114 an d a(N) = 0.201 mT, while for dichloro-[BB-123-TSA](+) g = 2.021 and a( N) = 0.44 mT. Further oxidation of both rings affords the correspondin g dications, both of which have been characterized crystallographicall y as their AlCl4- salts. The structural features of these compounds ar e consistent with those expected for dithiazolylium (or thiaselenazoly lium) derivatives. The structure and redox chemistry of the benzo[l,2- d:4,5-d']bis(l,2,3-dithiazole) framework is discussed in the light of the results of ab initio calculations.