A NMR-STUDY OF SOME SYDNONES, ISOSYDNONES AND ISOTHIOSYDNONES

Multinuclear H-1, C-13, N-14, N-15 and O-17 NMR data are presented for some sydnones, isosydnones and isothiosydnones. The type of valence t automerism shown in (Pig. 1) is not observed for the compounds studied . At high pH compounds 2 and 12 are found to undergo transformations. The more suitable NMR parameters are reported for establishing the str uctures of mesoionic compounds containing three heteroatoms in the fiv e-membered conjugated ring. Some ab initio GIAO calculation on a model structure of sydnones and related compounds have been performed.