Crystal, molecular and electronic structure of 1-H-3-methyl-4-amine-5-thione-1,2,4-triazol

Abstract

The crystal and molecular structure of the title compound has been determined from three-dimensional X-ray intensity data. The crystals are orthorhombic with space group Pbcm, a = 8.877(4), b = 9.813(2), c = 6.545(2) Å, Z = 4. The structure has been refined to R = 0.029 and Rw = 0.035. The molecules are present in the thione form as planar molecules with only intermolecular interactions. Bond lengths and angles suggest that the electron density is more localized in the N—N—C—S ring fragment. Theoretical calculations (MNDO method) were also carried out on the compound both in the thione and its thiol tautomeric forms. Some comparisons are made between several properties (formation enthalpies, proton affinities, molecular electrostatic potentials, atomic charges) of both tautomers. The results indicate some important differences in reactivity between both forms. Keywords: crystal structure, molecular structure, electronic structure, 1-H-3-methyl-4-amine-5-thione-1,2,4-triazol.