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From High-Temperature Orientationally Disordered Mixed Crystals to Low-Temperature Complex Formation in the Two-Component System (CH3)3CBr + Cl3CBr

hal.structure.identifierDepartament de Fisica i Enginyeria Nuclear [UPC, Barcelone] [ETSEIB]
dc.contributor.authorBARRIO, María
hal.structure.identifierLaboratoire Ondes et Matière d'Aquitaine [LOMA]
dc.contributor.authorNÉGRIER, Philippe
hal.structure.identifierDepartament de Fisica i Enginyeria Nuclear [UPC, Barcelone] [ETSEIB]
dc.contributor.authorTAMARIT, Jose Lluis
hal.structure.identifierLaboratoire Ondes et Matière d'Aquitaine [LOMA]
dc.contributor.authorMONDIEIG, Denise
dc.date.created2010-10-10
dc.date.issued2011
dc.identifier.issn1520-6106
dc.description.abstractEnThe phase diagram of the two-component systems (CH3)3-CBr+ Cl3CBr has been experimentally determined by means of differential scanning calorimetry and X-ray powder diffraction techniques from the low-temperature ordered phases to the liquid state. Before melting, both components have the same orientationally disordered (OD) facecentered cubic (FCC) and rhombohedral (R) phases, and the two-phase equilibria [FCC + L] and [R + FCC] are accounted for by means of the existence of an isomorphic relationship between the OD phases of pure compounds. The thermodynamic assessment of such equilibria enables us to get the excess properties of the involved OD phases and to rationalize the existence of a maximum and a minimum in the [R + FCC] equilibrium on the basis of the contribution of the entropic term in the excess Gibbs energy function. At low temperature, two complexes, (CH3)3CBr:Cl3CBr (1:1) and (CH3)3CBr:2Cl3CBr (1:2), appear. The structures of 1:1 and 1:2 complexes have been determined to be monoclinic (P21/n, c, Z = 4) and hexagonal (P63, Z = 6). Within both "ordered" structures, the Cl3CBr entities of the asymmetric unit were found to be disordered so that sites have fractional occupancies of 0.75 and 0.25 for Cl and Br atoms, in the same way that it occurs for the lowtemperature monoclinic (C2/c, Z = 32) phase of Cl3CBr. Finally, the existence of complexes is connected with the special intermolecular interactions appearing between a methyl group and a halogen, as previously inferred by Calvet et al. [T. Calvet et al. J. Chem. Phys. 1999, 110, 4841].
dc.language.isoen
dc.publisherAmerican Chemical Society
dc.rights.urihttp://creativecommons.org/licenses/by-nc-sa/
dc.title.enFrom High-Temperature Orientationally Disordered Mixed Crystals to Low-Temperature Complex Formation in the Two-Component System (CH3)3CBr + Cl3CBr
dc.typeArticle de revue
dc.identifier.doi10.1021/jp109702t
dc.subject.halPhysique [physics]/Matière Condensée [cond-mat]/Science des matériaux [cond-mat.mtrl-sci]
dc.subject.halChimie/Cristallographie
dc.subject.halChimie/Chimie théorique et/ou physique
bordeaux.journalJournal of Physical Chemistry B
bordeaux.page1679-1688
bordeaux.volume115
bordeaux.issue7
bordeaux.peerReviewedoui
hal.identifierhal-00608311
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-00608311v1
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