The crystal and molecular structures of 1,2,7,9-tetrathia-3,6,8,10-tetra-aza-cyclohept(e)indene, a novel tricyclic carbon–sulphur–nitrogen ring system

The crystal and molecular structures of 1,2,7,9-tetrathia-3,6,8,10-tetra-aza-cyclophept(e)indene, a novel carbon–sulphur–nitrogen heterocycle based on the phenazulene ring system, are reported. Crystals of the compound are orthorhombic, space group Pbca, a = 7.1334(8), b = 14.761(2), c = 16.677(2) Å, V = 1756.0(3) ų, Z = 8. The structure was solved by direct methods and refined by full-matrix least-squares procedures to a final R = 0.044 and R_w = 0.027. Molecules of the title compound consist of a five-membered [Formula: see text] ring and a seven-membered [Formula: see text] ring fused to a benzene ring. Internal structural parameters and the cell packing pattern suggest a dipolar charge distribution. The molecules are stacked in parallel planes in a head-to-tail fashion; the interplanar separation is 3.39 Å and the angle between the molecular planes and the a axis is 18°. The electronic spectrum of the molecule is discussed in relation to the perimeter model.