STRUCTURE OF THE ORGANIC CONDUCTOR (BEDT-TTF)2BR.C2H4(OH)2

Bis[3,4;3',4'-bis(ethylenedithio)-2,2',5,5'-tetrathiafulvalenium] bromide-ethylene glycol (1/1), 2C10H8S8(1/2+).Br-.C2H6O2, M(r) = 911.3, monoclinic, P12(1)/nl, a = 14.950 (2), b = 33.692 (4), c = 6.621 (1) angstrom, beta = 92.44 (1)-degrees, V = 3331.8 (8) angstrom 3, Z = 4, D(x) = 1.82 g cm-3, Cu K-alpha, lambda = 1.541 angstrom, mu = 107.1 cm-1, R = 0.071 for a total of 3115 independent reflections. The title compound is a new organic conductor [sigma(300) - 8 OMEGA 1cm-1, with a metal-insulator transition at T = 196 K]. The structure is laminated. Cation and anion layers are parallel to the ac plane and alternate along the b axis. BEDT-TTF cations form stacks along the a axis. The anion layers consist of Br- ions and ethylene glycol molecules linked by hydrogen bonds, Br...H-O. In the cation layer, BEDT-TTF ions from neighbouring stacks are linked, in side-by-side band, by short intermolecular contacts S...S 3.448 (4)-3.508 (4) angstrom. No short S...S contacts were found in the stacks.