VIBRATIONAL STUDY OF 1,2,4-TRIAZOLE-THION E AND ITS N-METHYL DERIVATIVES - TAUTOMERISM AND ASSOCIATION

The vibrational spectra of triazole-thione. 1-methyl-triazole-thione, 4-methyl-triazole-thione, 1,4-dimethyl-triazolethione and their deuter ated homologues have been studied in the range 4000-200 cm(-1). An ass ignment of the normal modes is proposed. From this analysis. we conclu de that triazole-thione and its N-methyl derivatives exist in only one tautomeric form in the solid state. The comparison of the vibrational spectra in the solid state of 4-methyl-triazolethione with those of s olutions in various polar solvents enables us to explain the presence of two absorptions assigned to gamma(CH) and gamma(NH) modes of this m olecule by CH and NH groups in different environments. (C) 1997 Elsevi er Science B.V.