PREPARATION AND SOLID-STATE STRUCTURAL, ELECTRONIC, AND MAGNETIC-PROPERTIES OF THE 1,3,5-BENZENE-BRIDGED TRIS(1,2,3,5-DITHIADIAZOLYL) [1,3,5-C6H3(CN2S2)3]

The preparation and solid-state characterization of the trifunctional radical 1,3,5-benzenetris(1,2,3,5-dithiadiazolyl) [4,4',4''-(1,3,5-benzenetriyl)tris[1,2,3,5-dithiadiazolyl], 1,3,5-C6H3(CN2S2)3] are described. The crystals belong to the monoclinic space group P2(1)/c, with a = 6.927 (2), b = 19.798 (3), c = 19.393 (3), and beta = 99.80 (2) angstrom3. The crystal structure consists of stacks of triradicals running parallel to x. Each radical center associates with a neighboring radical, generating alternating long (mean 3.832 angstrom) and short (mean 3.117 angstrom) interradical S...S contacts along the stack; only two of the three crystallographically distinct bond alternation waves so generated are in-phase. The packing of triradical stacks produces an extensive network of close interstack S...S contacts. The compound is diamagnetic at room temperature, but paramagnetic defects begin to appear near 450 K. The room-temperature single-crystal conductivity is near 10(-7) S cm-1. Extended Huckel band structure calculations reveal a band pp of 0.8 eV.