13C NMR chemical shifts of benzophenone azine as a benchmark for configurational assignment of azines with aromatic substituents

An analysis of the ¹³C NMR spectral data and quantum chemical calculations for benzophenone azine shows that the shielding constant of the C _ipso atom of its molecule is stereo-specific. The characteristic difference in chemical shifts of the C _ipso atoms of the phenyl rings in the cis- and trans-positions with respect to the lone pair of the neighboring nitrogen atom is 2–3 ppm. The stereospecificity observed for chemical shifts was proposed to be used for the configurational assignment of azines containing aromatic substituents.