title: Experimental and theoretical study of the structures and enthalpies of formation of the synthetic reagents 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione.
abstract: This paper reports an experimental and a theoretical study of the structures and standard (p(o) = 0.1 MPa) molar enthalpies of formation of the synthetic reagents 1,3-thiazolidine-2-thione [CAS 96-53-7] and 1,3-oxazolidine-2-thione [CAS 5840-81-3]. The enthalpies of combustion and sublimation were measured by rotary bomb combustion calorimetry, and the Knudsen effusion technique and gas-phase enthalpies of formation values at T = 298.15 K of (97.1 +/- 4.0) and -(74.4 +/- 4.6) kJ.mol(-1) for 1,3-thiazolidine-2-thione and 1,3-oxazolidine-2-thione, respectively, were determined. G3-calculated enthalpies of formation are in reasonable agreement with the experimental values. In the solid state, 1,3-thiazolidine-2-thione exists in two polymorphic forms (monoclinic and triclinic) and 1,3-oxazolidine-2-thione exits in the triclinic form. The isostructural nature of these compounds and comparison of their molecular and crystal structures have been analyzed. The experimental X-ray powder diffractograms have been compared with the calculated patterns from their structures for identification of the polymorphic samples used in this study. A comparison of our results with literature thermochemical and structural data for related compounds is also reported.
authors.affiliation: Instituto de Quimica Fisica Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain. victoriaroux@iqfr.csic.es
authors.forename: María Victoria
authors.initials: MV
authors.lastname: Roux
authors.forename: Manuel
authors.initials: M
authors.lastname: Temprado
authors.forename: Pilar
authors.initials: P
authors.lastname: Jiménez
authors.forename: Concepción
authors.initials: C
authors.lastname: Foces-Foces
authors.forename: Rafael
authors.initials: R
authors.lastname: Notario
authors.forename: Archana R
authors.initials: AR
authors.lastname: Parameswar
authors.forename: Alexei V
authors.initials: AV
authors.lastname: Demchenko
authors.forename: James S
authors.initials: JS
authors.lastname: Chickos
authors.forename: Carol A
authors.initials: CA
authors.lastname: Deakyne
authors.forename: Alicia K
authors.initials: AK
authors.lastname: Ludden
authors.forename: Joel F
authors.initials: JF
authors.lastname: Liebman