Synthesis and structure of anils of 2-formyl-3-mercaptobenzo[b]thiophene and 2-formyl-3-mercaptobenzofuran

As a result of a study of the electronic, vibrational, and PMR spectra of alkyl- and arylimines of 2-formyl-3-mercaptobenzo[b]thiophene and 2-formyl-3-mercaptobenzofuran and of the spectra of model compounds the thione-enamine structure was assigned to the imines. The stability of the latter structure is in agreement with the results of quantum-mechanical calculations of the energies of atomization of the individual tautomeric forms; the calculations were made by means of the Pariser-Parr-Pople (PPP) method with the Dewar σ, π parametrization.