Synthesis and structure of 2-hydroxy-3-formylbenzo[b]thiophene azomethines

A number of 2-hydroxy-3-formylbenzo[b]thiophene azomethines and their derivatives, which model the individual tautomeric forms, were synthesized. As a result of a study of the electronic, vibrational, and PMR spectra, a ketone-amine structure, the stability of which is confirmed by quantum-mechanical calculations of the atomization energies of the individual tautomeric forms calculated by the Pariser-Parr-Pople (PPP) method within the Dewar , parametrization, was assigned to these azomethines.Communication XVIII from the series Benzoid—Quinoid Tautomerism of Azomethines and Their Structural Analogs. See [1] for communication XVII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 635–642, May, 1975.