Publication Type Journal Article
Title Structural and energetic characterization of anhydrous and hemihydrated 2-mercaptoimidazole: Calorimetric, X-ray diffraction, and computational studies
Authors Ana L. R. Silva Victor M. F. Morais Maria D. M. C. Ribeiro da Silva R. A. G. Simões Carlos E. S. Bernardes M.Fatima M.Piedade M. E. M. Piedade
Groups MET BIOMOL
Journal JOURNAL OF CHEMICAL THERMODYNAMICS
Year 2016
Month April
Volume 95
Number
Pages 35-48
Abstract This paper reports an experimental and theoretical study on the structural and energetic characterization of the 2-mercaptoimidazole (2-MI) in the solid and in the gaseous phases. The single crystal X-ray diffraction determinations on the anhydrous and hemihydrate 2-MI forms were carried out at T = (296 +/- 2) K and T = (150 +/- 2) K, respectively, and suggest that in both forms the 2-MI molecule is closer to the thione conformation, albeit some single bond character is possible. The energy of combustion of the title compound was measured by rotating-bomb combustion calorimetry, being used to derive the corresponding enthalpy of formation in the crystalline-phase. The enthalpy of sublimation of 2-MI, at T = 298.15 K, was obtained from high temperature Calvet microcalorimetry measurements. These two parameters yielded the gas-phase enthalpy of formation, allowing the inherent energetic analysis of the molecule. This result was discussed together with the corresponding predictions for 2-MI and its tautomer, 1,3-dihydro-2H-imidazole-2-thione, by the G3 method. The dehydration reaction of 2-MI center dot 0.5H(2)O(cr) was also investigated and the corresponding enthalpy of dehydration was determined by Calvet microcalorimetry. (C) 2015 Elsevier Ltd. All rights reserved.
DOI http://dx.doi.org/10.1016/j.jct.2015.11.010
ISBN
Publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
Book Title
ISSN 0021-9614
EISSN 1096-3626
Conference Name
Bibtex ID ISI:000368762600005
Observations
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