MULTINUCLEAR MAGNETIC-RESONANCE STUDY OF SOME MESOIONIC 1,3,4-TRIAZOLES

H-1, C-13, N-14 and N-15 NMR data are reported for a series of mesoino ic 1,3,4-triazoles and some of their salts, The results obtained show that the molecules studied exist in the cyclic mesoionic form with del ocalization of the positive charge over the ring atoms, The correspond ing negative charge occurs on the atoms of the exocyclic groups, which also act as the site of protonation and salt formation. The most impo rtant experimental data for these interpretations are found to be the nitrogen shieldings and that for C-5.