Synthesis and Structure of 5-Aryl-1,2,4-Triazole-3-Thione Derivatives. Aromaticity of the 1,2,4-Triazole Ring

Abstract Some 1,2,4-triazole-3-thione derivatives are obtained, and their structures are determined from ¹H and ¹³C NMR spectroscopy data, as well as the single crystal X-ray diffraction analysis (SCXRD). Based on the SCXRD results and DFT calculations, the aromaticity of the 1,2,4-triazolethione ring is evaluated using the Multiwfn software package. The aromaticity is assessed in four possible tautomers A-D that are energetically readily formed in the thioamide moiety because of the migration of two H atoms and formally double bonds. The comparison of the Bird aromaticity values of the 1,2,4-triazole ring in the four tautomers in the model and synthesized compounds shows that in two tautomers B, D the aromaticity is shown has a high value, while in tautomers A, C it drops. The tautomeric state is shown to play an important role in assessing the 1,2,4-triazole ring aromaticity.

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