Vibrational And Theoretical Analysis Of The Protonation Of 3,4'-Bi-1,2,,4-Triazole And Its C-Bromo And C-Methyl Derivatives

An approach to determine the structure of protonated 3,4 ' -di-1,2,4-triazoles was carried out using the semi-empirical M.N.D.O. (modified neglect of diatomic overlap)method. ne results obtained for 3,4 ' -di-1,2,4-triazole show that the isolated state of the NH form has great stability, and lead to the conclusion that its protonation mainly occurs on one of the pyridine nitrogen of the 4-triazolyle group.The vibration spectra of the di-1,2,4-triazolium, 5-methyl di-1,2,4-triazolium and 5-bromo di-1,2,4-triazolium chlorides were studied between 4000 and 200 cm(-1). An attribution of the fundamental modes is proposed, and the effect of protonation on the normal vibration frequencies is discussed. Using these spectroscopic results, the strength and type of hydrogen bonds existing in the crystal could be assessed and a molecular structure proposed.