Interplay between intramolecular and intermolecular structures of 1,1,2,2-tetrachloro-1,2-difluoroethane

Abstract

We report on the interplay between the short-range order of molecules in the liquid phase of 1,1,2,2-tetrachloro-1,2-difluoroethane and the possible molecular conformations, trans and gauche. Two complementary approaches have been used to get a comprehensive picture: analysis of neutron-diffraction data by a Bayesian fit algorithm and a molecular dynamics simulation. The results of both show that the population of trans and gauche conformers in the liquid state can only correspond to the gauche conformer being more stable than the trans conformer. Distinct conformer geometries induce distinct molecular short-range orders around them, suggesting that a deep intra-and intermolecular interaction coupling is energetically favoring one of the conformers by reducing the total molecular free energy.

Orientational relaxations in solid (1,1,2,2)tetrachloroethane

“…1(b) the maximum of the α loss is outside the depicted frequency range, so that the low-frequency background visible in the spectra corresponds to the high-frequency tail of such loss. 8 The real permittivity spectra ε'(f) (shown in the inset in Fig. 1(b) for the temperature of 193.2 K) are monotonically decreasing functions of frequency, as expected.…”

“…Orientationally disordered (OD) phases are generally formed by relatively small globular molecules such as derivatives of methane, 1,2,3 neopentane, 4 adamantane 5 or fullerene, 6 or by small linear ones such as ethane derivatives 7,8,9 and dinitriles. 10 OD solids exhibit many of the phenomenological features of glass formers, displaying in particular a cooperative rotational motion, called α relaxation, that undergoes a continuous, dramatic slow-down upon cooling, 11,12 leading in some cases to a glass-like transition associated with rotational freezing.…”

Thermal properties of halogen-ethane glassy crystals: Effects of orientational disorder and the role of internal molecular degrees of freedom

“…[14][15][16][17][18][19] Halogen-ethane derivatives have been thoroughly characterized macroscopically (heat capacity, thermodynamic magnitudes, phase transitions, etc.) and microscopically (molecular dynamics, crystallographic structure, relaxation dynamics, molecular structure, etc.)…”

“…seeking to find a relation between its physical properties and its intermolecular interactions, as well as its intramolecular features, which can influence both the short-and the long-range order. [14][15][16][17][18][19][20][21][22] F-112 and F-113 are archetypal examples in which a mixture of conformers is present, and for which a complicated sequence of calorimetric transitions appears. Figure 1 shows the two F-112 conformers, gauche and trans, and the two F-113 conformers, C 1 and C s .…”

Fitting in a complexχ2landscape using an optimized hypersurface sampling

“…More complex problems have already successfully been studied with this algorithm such as model selection using Quasielastic Neutron Scattering data [25], non-functional fits in the case of dielectric spectroscopy [26] or finding the molecular structure from diffraction data with a model defined by as many as 27 parameters [27]. In the last case, the proper initialization of parameters to use a LM algorithm would have been a difficult task, made easy by the use of the presented algorithm.…”