Synthesis and vibrational spectra of N-exo-arylcarbamoylsydnoneimines and their salts
A number of arylcarbamoyl derivatives of sydnoneimines were synthesized, and their IR spectra and Raman spectra in the region of the characteristic vibrations of the exocyclic bond were studied. The integral intensities (A) of the C=O and C=N bands of those compounds constitute evidence for effective electronic interaction of the atoms in the exocyclic group. The structures of salts of the carbamoylsydnoneimines were investigated by means of their IR spectra, and it was proved that the protonation of these compounds takes place at the exocyclic nitrogen atom. It is shown that carbamoylsydnoneimines do not form dications even in solutions of strong acids.