Negrier Philippe, Barrio María, Tamarit Josep Ll, Mondieig Denise
Univ. Bordeaux and ‡CNRS, LOMA, UMR 5798 , F-33400 Talence, France.
J Phys Chem B. 2014 Aug 14;118(32):9595-603. doi: 10.1021/jp505280d. Epub 2014 Aug 5.
The polymorphism of two 2-X-adamantane derivatives, X = Cl, X = Br, has been studied by X-ray powder diffraction and normal- and high-pressure (up to 300 MPa) differential scanning calorimetry. 2-Br-adamantane displays a low-temperature orthorhombic phase (space group P212121, Z = 4) and a high-temperature plastic phase (Fm3̅m, Z = 4) from 277.9 ± 1.0 K to the melting point at 413.4 ± 1.0 K. 2-Cl-adamantane presents a richer polymorphic behavior through the temperature range studied. At low temperature it displays a triclinic phase (P1̅, Z = 2), which transforms to a monoclinic phase (C2/c, Z = 8) at 224.4 ± 1.0 K, both phases being ordered. Two high-temperature orientationally disordered are found for this compound, one hexagonal (P63/mcm, Z = 6) at ca. 241 K and the highest one, cubic (Fm3̅m, Z = 4), being stable from 244 ± 1.0 K up to the melting point at 467.5 ± 1.0 K. No additional phase appears due to the increase in pressure within the studied range. The intermolecular interactions are found to be weak, especially for the 2-Br-adamantane compound for which the Br···Br as well as C-Br···H distances are larger than the addition of the van der Waals radii, thus confirming the availability of this compound for building up diamondoid blocks.
通过X射线粉末衍射以及常压和高压（高达300 MPa）差示扫描量热法研究了两种2-X-金刚烷衍生物（X = Cl，X = Br）的多晶型性。2-溴金刚烷在277.9±1.0 K至熔点413.4±1.0 K范围内呈现低温正交相（空间群P212121，Z = 4）和高温塑性相（Fm3̅m，Z = 4）。在研究的温度范围内，2-氯金刚烷呈现出更丰富的多晶型行为。在低温下，它呈现三斜相（P1̅，Z = 2），在224.4±1.0 K时转变为单斜相（C2/c，Z = 8），这两个相都是有序的。该化合物发现了两种高温取向无序相，一种是在约241 K时的六方相（P63/mcm，Z = 6），最高的是立方相（Fm3̅m，Z = 4），从244±1.0 K到熔点467.5±1.0 K都是稳定的。在研究范围内，压力增加没有出现额外的相。发现分子间相互作用较弱，特别是对于2-溴金刚烷化合物，其Br···Br以及C-Br···H距离大于范德华半径之和，从而证实了该化合物可用于构建类金刚石块。
