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]

Abstract

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 P21/c, with a = 6.927 (2), b = 19.798 (3), c = 19.393 (3), and β = 99.80 (2) Å3. 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 Å) and short (mean 3.117 Å) 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 Hückel band structure calculations reveal a band gap of 0.8 eV.