A Bimodal Oxobenzene-bridged Bisdithiazolyl Radical Conductor

The preparation and structural characterization of the methyl-substituted oxobenzene-bridged bisdithiazolyl radical 3b is described. Crystals of 3b belong to the monoclinic space group C2/c and contain two distinct radical environments, A and B. There are eight A radicals in the unit cell, which occupy general positions and form alternating twisted π-stacks running parallel to the c-axis. The four B radicals also adopt an alternating π-stack pattern, but each molecule lies on a crystallographic 2-fold rotation axis, and the overlay of neighboring radicals is centrosymmetric. Stacks of A radicals are linked by close intermolecular S···O′ and S···N′ contacts into ribbon-like arrays that weave along the y-direction, and the B radical stacks are located in columnar cavities generated by the out-of-register alignment of the ribbons of A radicals. Variable temperature magnetic susceptibility measurements indicate a strongly antiferromagnetically coupled system, a result in accord with DFT estimated exchange energies for intrastack radical–radical interactions. Four-probe conductivity measurements indicate a conductivity σ­(300 K) = 9.0 × 10–4 S cm–1, with a thermal activation energy Eact = 0.13 eV.