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首页> 外文期刊>Acta Crystallographica, Section B. Structural science, crystal engineering and materials >Melting point, molecular symmetry and aggregation of tetrachlorobenzene isomers: the role of halogen bonding
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Melting point, molecular symmetry and aggregation of tetrachlorobenzene isomers: the role of halogen bonding

机译：四氯苯异构体的熔点，分子对称和聚集：卤素键的作用

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摘要

Tetrachlorobenzenes represent one of the best known, but not yet fully understood, group of isomers of the structure-melting point relationship. The differences in melting temperatures of these structurally related compounds were rationalized in terms of the hierarchy and nature of formed noncovalent interactions, and the molecular aggregation that is influenced by molecular symmetry. The highest melting point is associated with the highly symmetric 1,2,4,5-tetrachlorobenzene isomer. The structures of less symmetrical 1,2,3,4-tetrachlorobenzene and 1,2,3,5-tetrachlorobenzene, determined at 270 and 90 K, show a distinct pattern of halogen bonds, characterized by the different numbers and types of interactions. The evolution of Cl···Cl/H distances with temperature indicates the attractive character of intermolecular interactions and their importance to the structural and thermodynamic parameters of isomeric compounds. The favoured Cl···Cl halogen bonds were found to play a decisive role in differentiating the melting temperatures of tetrachlorobenzene isomers. It was also found that, besides the molecular symmetry and ability to form specific intermolecular interactions, both the type and the distribution of interactions are the important factors responsible for the melting behaviour of the studied isomers. The observed preferences, in tetrachlorobenzenes, for the formation of specific noncovalent interactions correspond to the distribution of calculated partial atomic charges and to the magnitudes of electrostatic potential on the molecular surfaces as well as correlate with the enthalpy of melting parameters.
机译：四氯苯代表了最着名的，但尚未完全理解的是结构熔点关系的基础。这些结构相关化合物的熔化温度的差异在形成的非共价相互作用的等级和性质方面是合理化的，以及由分子对称影响的分子聚集。最高熔点与高度对称的1,2,4,5-四氯苯异构体有关。在270和90K处测定的较少对称的1,2,3,4-四氯苯和1,2,3,5-四氯苯的结构，显示出不同的卤素键模式，其特征在于不同的数量和相互作用。 Cl···Cl / H距离的距离与温度的距离表示分子间相互作用的有吸引力及其对异构化合物的结构和热力学参数的重要性。发现有利于Cl···Cl卤素键在区分四氯苯异构体的熔化温度方面发挥着决定性作用。还发现，除了分子对称和形成特异性分子间相互作用的能力之外，相互作用的类型和分布都是负责研究的异构体熔化行为的重要因素。在四氯苯中，观察到的偏好，用于形成特定的非共价相互作用对应于计算出的部分原子电荷的分布和分子表面上的静电电位幅度以及与熔化参数的焓相关。

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