Tautomeric conversion, vibrational spectra, and density functional studies on peripheral sulfur derivatives of benzothiazole and benzothiazoline isomers

摘要: The room temperature structural (tautomerism, dimerization, conformational preference, geometry parameters) and vibrational spectral (IR Raman) analyses have been performed on benzothiazoline (benzothiazoline-2-thione, 3-methyl-benzothiazoline-2-thione) benzothiazole [2-mercaptobenzothiazole, 2-methylthiobenzothiazole, bis(benzothiazole-2-ylthio)ethane] derivatives at the B3LYP/6-311++G∗∗ level of theory. Although keto to enol transition barriers are too high over most stable isomers, reveal some major bands isomers in present experimental FT-IR FT-Raman specta. Therefore, exist rare amounts powdered samples that mainly composed isomers. two conformations due orientation their SH SCH3 moieties. energetic suggest benzothiazoline-2-thione molecules can be stabilized further through NH⋯S intermolecular hydrogen bonds solid phase. All observed fundamental assigned based calculated mode frequencies IR/Raman intensities. assignments expressed terms internal coordinates percent potential energy distributions. effects substitution nitrogen peripheral sulfur atoms analyzed for geometries molecules.