Trithiocyanuric acid: novel cocrystals and analysis of its tautomeric forms.

Cocrystals of trithiocyanuric acid with 2,2'-bipyridyl [1,3,5-triazinane-2,4,6-trithione-2,2'-bipyridine (2/1), 2C3H3N3S3·C10H8N2, (I)] and 4-methylbenzohydrazide [1,3,5-triazinane-2,4,6-trithione-4-methylbenzohydrazide (1/1), C8H10N2O·C3H3N3S3, (II)] crystallize in the monoclinic crystal system. In the crystals, molecules of both components are linked by hydrogen bonds. The trithiocyanuric acid molecules are connected by N-H...S hydrogen bonds forming R22(8) synthons, which are further organized into chain motifs. Computations based on quantum chemistry methods have been performed for a more detailed description of the observed tautomerism of trithiocyanuric acid.