Étude de la tautomérie des halogéno-triazoles-1,2,4 par determination expérimentale et théorique de leurs moments dipolaires

The dipole moments of sixteen 3(5)-halogeno-triazoles have been measured in dioxane at 25 ° C. Experimental dipole moments have been compared with those calculated by two semi-empirical methods CNDO/2 and PCILO, and with those computed vectorially. An energetic approach is also given.It is shown, in _N-unsubstituted 1,2,4-triazoles (for which three tautomeric forms, A, B and C are possible) that the predominating tautomer has a proton on the N1 atom and the electron-accepting substituent on the C3 atom.The effect of the introduction of an electron-accepting or donating substituent in position 3 and 5 of the triazole ring is discussed.