Aw. Cordes et al., PREPARATION AND SOLID-STATE CHARACTERIZATION OF ISOSTRUCTURAL BIFUNCTIONAL 1,2,3,5-DITHIADIAZOLYLS WITH BENZENE, BITHIOPHENE, AND PIPERAZINE SPACERS, Inorganic chemistry, 35(26), 1996, pp. 7626-7632
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.