Six new derivatives of mesoionic 3-phenyl-5-imino-1, 2, 3, 4-oxatriazole imine have been obtained and investigated by 1H, 13C, 14N, 15N and 17O NMR techniques. The 15N and 17O NMR studies reveal that mesoionic oxatriazoles imines exist in a cyclic,'mesoionic'form. Two stable conformers of mesoionic 3-phenyl-5-imino-1, 2, 3, 4-oxatriazole imines, E and Z, in comparable concentrations, have been detected for the first time in the solution by the ...