CYCLIC ARYLENEAZACHALCOGENENES .6. SYNTHESIS, CRYSTAL AND MOLECULAR-STRUCTURE OF 5,6,7,8-TETRAFLUORO-1,3,2,4-BENZODITHIADIAZINE, A FORMALLY ANTIAROMATIC STABLE COMPOUND

1-Pentafluorophenyl-4-trimethylsilyl-2,4-diaza-1,3-dithia-2,3-butadiene is cyclized by CsF in acetonitrile to 5,6,7,8-tetrafluoro-1,3,2,4-benzodithiadiazine (54% yield), a thermodynamically stable formally antiaromatic 12-pi-electron compound having an almost planar molecular geometry, as shown by the X-ray structure analysis data. The crystal and molecular structure of the polyfluorinated derivative appreciably differ from those of its hydrocarbon analogue, 1,3,2,4-benzodithiadiazine.