An interesting isomerization: Synthesis of mesoionic 5-arylamino-1,3,4-thiadiazolium-2-thiolates by using omega-bromo-omega-(1H-1,2,4-triazol-1-yl)acetophenone as catalyst

Mesoionic 5-arylamino-1,3,4-thiadiazolium-2-thiolates 7a-f were prepared by the isomerization of 5-arylamino-1,3,4-thiadiazol-2-thiones 5a-f by using omega -bromo-omega-(1H-1,2,4-triazol-1-yl)acetophenone 6 as catalyst. All t he structures of mesoionic synthesized were confirmed by elemental analyses , H-1 NMR, IR and MS spectral data. We have also determined the x-ray photo electron spectroscopy (XPS) of the mesoionic and their precursors. A compar ison of XPS spectra between the mesoionic and their precursors showed that the charge separation in mesoionic is distinctly larger than in their precu rsors.