Abstract
Abstract The reaction of phthalic acid anhydride with isonicotinoylhydrazide is carried out under severe conditions with the formation of cyclic phthalic acid imide N-isonicotinoylphthalimide. The structure of the compound is determined by 1H and 13C NMR spectroscopy and from the data of two-dimensional (1H–1H) COSY and (1H–13C) HMQC spectra. The spatial structure and conformation of N-isonicotinoylphthalimide is investigated by single crystal XRD and a semi-empirical quantum chemical method. It is found that π-conjugation between the phenyl and carbonyl groups is practically absent in the free N-isonicotinoylphthalimide molecule and a rotation of the pyridine ring relative to the amide group in the crystal is determined by the π–π interaction between the pyridine rings.