Single crystals of isomeric 1,2,3-tribromobenzene (123TBB), 1,2,4-tribromobenzene (124TBB) and 1,3,5-tribromobenzene (135TBB) have been grown from different solvents and their structures determined by X-ray diffraction at 100, 200 and 270 K. The melting-point differences of ca 40 K between 135TBB, 123TBB and 124TBB have been correlated with the molecular symmetry and packing preferences in the crystal, as well as with the main types of intermolecular halogen interactions, i.e. Br…Br, Br…C (Br…π) and Br…H. The relationship between symmetry and melting point in Carnelley's rule has been extended to the accessibility of terminal atoms for the formation of intermolecular interactions, their occurrences and distribution, and the close packing. The electrostatic potential mapped on molecular surfaces demonstrates that in more symmetric molecules the more evenly distributed substituents are more accessible and form more optimum intermolecular interactions.

中文翻译：

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性质和相互作用 - 三溴苯异构体的熔点

异构体 1,2,3-三溴苯 (123TBB)、1,2,4-三溴苯 (124TBB) 和 1,3,5-三溴苯 (135TBB) 的单晶已从不同的溶剂中生长，并通过 X 射线确定其结构在 100、200 和 270 K 下的衍射。135TBB、123TBB 和 124TBB 之间约40 K的熔点差异与晶体中的分子对称性和堆积偏好以及分子间卤素相互作用的主要类型相关，IEBr…Br、Br…C (Br…π) 和 Br…H。Carnelley 规则中对称性和熔点之间的关系已经扩展到末端原子的可及性以形成分子间相互作用、它们的出现和分布以及紧密堆积。映射在分子表面的静电势表明，在更对称的分子中，更均匀分布的取代基更容易接近并形成更佳的分子间相互作用。