PREPARATION AND SOLID-STATE CHARACTERIZATION OF ISOSTRUCTURAL BIFUNCTIONAL 1,2,3,5-DITHIADIAZOLYLS WITH BENZENE, BITHIOPHENE, AND PIPERAZINE SPACERS

The preparation of the bis(1,2,3,5-dithiadiazolyl) radicals [S2N2C]-X- [CN2S2], where X is a heterocyclic bridging group (X = piperazine, thi ophene, bithiophene) is described. Crystal structures of the piperazin e- and bithiophene-bridged diradicals have been determined by single-c rystal X-ray diffraction. The two compounds are isostructural, belongi ng to the monoclinic space group P2(1)/n; for the piperazine derivativ e a = 5.9913(6) Angstrom, b = 19.1958(16) Angstrom, c = 9.1244(6) Angs trom, beta = 100.314(7)degrees, and Z = 4. For the bithiophene derivat ive a = 5.9907(17) Angstrom, b = 24.272(3) Angstrom, c = 9.1740(14) An gstrom, beta = 102.961(18)degrees, and Z = 4. The diradicals associate as cofacial dimers which adopt a herringbone packing pattern analogou s to that observed previously for the 1,4-phenylene-bridged derivative . in all three structures the herringbone arrays are characterized by a series of close interdimer S-S contacts along the spine. Consistentl y, the results of extended Huckel band structure calculations indicate highly developed two-dimensional electronic structures.