Charge distribution and aromaticity in protonated urazole

Abstract

Urazol was reacted in various superacidic media, and its mono- and diprotonated species were isolated and characterized by Raman and NMR spectroscopy as well as single crystal X-ray structure determination. Quantum chemical calculations were employed to characterize charge localization with mapped electrostatic potentials and NPA charges. NICS(0) was calculated to evaluate the aromatic character of urazole and its cations. The results were used to compare the protonation of urazole to that of parabanic acid.