Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1252058 | Vibrational Spectroscopy | 2010 | 9 Pages |
Abstract
The tautomerism of benzoxazoline-2-thione (BOT; thio-keto) and 2-mercaptobenzoxazole (MBO; thio-enol) has been thoroughly investigated by means of Raman (3600-100 cmâ1), infrared (4000-200 cmâ1), 1H and 13C NMR spectra and X-ray powder diffraction (XRD). In addition, temperature-dependent 1H NMR spectra from â90 to +90 °C were acquired. To complement experimental results with theoretical predictions, we performed Density Functional Theory (DFT) calculations utilizing B3LYP, B3PW91 and SVWN methods at 6-31G(d) basis set. Both computational and spectral results were in favor of thio-keto BOT structure with no evidence for the existence of thio-enol (MBO) tautomer which firmly eliminates the possibility of an existing equilibrium between keto and enol forms. Moreover the dimerization percentage of thio-keto benzoxazoline-2-thione (BOT) and benzothiazoline-2-thione (BTT) were found to be 11.9% and 2.5%, respectively which favors strong hydrogen bonding interactions in BOT. Aided by normal coordinate analysis, force constants in internal coordinates and potential energy distributions (PEDs), a complete vibrational assignment for all fundamentals was obtained. The results are compared with the sulfur analogue, benzothiazoline-2-thione (BTT) whenever appropriate.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Tarek A. Mohamed, Ahmed M. Mustafa, Wajdi M. Zoghaib, Mahmoud S. Afifi, Rabei S. Farag, Yehia Badr,