Trithia­cyanuric acid: a second triclinic polymorph

The title compound, C(3)H(3)N(3)S(3), is a triclinic modification. The other reported modification crystallizes with just one mol­ecule in the asymmetric unit, [Guo et al. (2006 ▶). Cryst. Growth Des. 6, 846–848] and was solved by power X-ray diffraction data. The present modification has Z′ = 2. In the crystal, mol­ecules are linked by strong intra­molecular N—H⋯S hydrogen bonds with set graph-motif R (2) (2)(8). In both mol­ecules, all of the N atoms and two of the S atoms are involved in hydrogen bonding, with an average H⋯S distance of 2.58 Å and N—H⋯S angles in the range 163–167°. π–π stacking inter­actions are not observed. In the solid state, the mol­ecules exist in the thione form. The mol­ecular and supra­molecular properties are similar in both polymorphs.