High Pressure Effects on Zwitterionic and Thione Mesomeric Contributions in 2-Benzimidazole-2-Thione

Abstract

High pressure reduces the zwitterionic mesomeric contribution and increases the thione contribution in 2-benzimidazole-2-thione. These mesomeric changes are manifested in the shortened bond S–C and elongated bond C–N in the S–C–N moiety. These transformations are consistent with the le Chatelier law, as they counteract the increase of electrostatic interactions when the intermolecular distances between electronegative sulfur atoms and arene π-electrons are compressed. The changing interactions affect the crystal strain and its structural transformations. Consequently, the crystal compression and thermal expansion initially, until about 1.0 GPa, are inconsistent with the inverse relationship rule of pressure and temperature effects. Some anomalous features of the thermal expansion can be associated with isostructural transformations of the crystal.

Novel C3-Methylene-Bridged Indole Derivatives with and without Substituents at N1: The Influence of Substituents on Their Hemolytic, Cytoprotective, and Antimicrobial Activity

“…Figure 3 shows the following: (A) two tautomeric forms of imidazole-2-thiones (thione and thiol) and (B) their mesomeric effect. According to the literature data, the thione form is predominant in polar solvents and the solid state [16,[48][49][50][51][52][53][54][55]. The NMR spectra analysis confirmed the presence of the thione forms of the newly obtained gramine derivatives (2, 4, 6, 12, and 13) in the DMSO-d 6 solution.…”

“…Figure 3 shows the following: (A) two tautomeric forms of imidazole-2-thiones (thione and thiol) and (B) their mesomeric effect. According to the literature data, the thione form is predominant in polar solvents and the solid state [16,[48][49][50][51][52][53][54][55]. A crucial structural feature of azoles and benzazoles is the existence of tautomeric forms.…”