Ultraviolet–visible spectroscopic study of 3,5-dithio-2,7-dimethyl-[1,2,4]-triazepine: Qualitative analysis of tautomeric behaviour

Room temperature UV–vis absorption spectra of the tautomeric system 3,5-dithio-2,7-dimethyl-[1,2,4]-triazepine in solution, in acetonitrile (CH 3CN), are measured at different water volume percentages. The comparison of the obtained measures to the calculated allowed absorption transitions, using ZI...

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Bibliographic Details
Published in:Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2005-12, Vol.62 (4), p.875-879
Main Authors: Azzouzi, F., Lyazidi, S. Ait, Haddad, M., Messaoudi, M. El, Hasnaoui, A., Larbi, N. Ben
Format: Article
Language:English
Subjects:
Acetonitriles
Azepines - chemistry
Azepines - radiation effects
Dark/indirect sunlight effect
Darkness
Dithiol
Dithione
Hydrogen bond
Isomerism
Light
Solvents - chemistry
Spectrophotometry, Ultraviolet
Tautomers
Temperature
UV–vis absorption
Water - chemistry
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Summary:Room temperature UV–vis absorption spectra of the tautomeric system 3,5-dithio-2,7-dimethyl-[1,2,4]-triazepine in solution, in acetonitrile (CH 3CN), are measured at different water volume percentages. The comparison of the obtained measures to the calculated allowed absorption transitions, using ZINDO/S package, reveals the coexistence of all the tautomeric forms in aprotic polar solution with a high dominance of the dithione form. The solute–water hydrogen bond, which seems to be of 1: n-type, favours the dithiol and monothiol conformers to the detriment of the dithione one. Further experimental investigations lead to the result that standing at ambient Laboratory conditions in the dark favours the dithione tautomeric isomer, while standing at indirect sunlight shifts the tautomeric equilibrium away from this specie.
ISSN:1386-1425
DOI:10.1016/j.saa.2005.03.019