Charge Density Analysis and Topological Properties of Hal3-Synthons and Their Comparison with Competing Hydrogen Bonds
Charge Density Analysis and Topological Properties of Hal3-Synthons and Their Comparison with Competing Hydrogen Bonds
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DOI：
10.1021/cg300978x
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发表时间：
2012-11-01
影响因子：
3.8
通讯作者：
Espinosa, Enrique
中科院分区：
文献类型：
--
作者：
Brezgunova, Mariya E.;Aubert, Emmanuel;Espinosa, Enrique
研究了六氯苯、六溴苯、五氯苯酚和五溴苯酚中基于分子间卤素键相互作用的三聚体（Hal(3)-synthons）。基于实验和理论的电荷密度分析，对Cl-3-和br -3-合子进行了比较，并讨论了它们与氢键的竞争。Cl-3-和Br-3-合子的主要区别在于Cl和Br原子中价壳电荷浓度区的特殊结构。亲电-亲核相互作用发生在Hal(3)-合子的分子间区域，通过放置属于卤素原子价壳层的面对面电荷耗尽（CD）和电荷集中（CC）区域。静电相互作用遵循这些区域的亲电性和亲核性，并通过L(r) = -del(2)rho(r)函数的相应拓扑临界点（CPs）上归一化为电荷密度单位（L/rho）的负拉普拉斯值来监测。根据p(r)和L(r)的CPs的拓扑和能量性质，可以观察到Hal(3)-synthons可以成功地与所分析结构中的分子间HBs竞争。根据估计的相互作用能和静电描述子δ (L/rho) = (L/rho)(CC) - (L/rho)(CD)，我们得出结论，强色散贡献有助于Hal3-synthons在这场竞争中获胜。
Trimers based on intermolecular halogen-bonding interactions (Hal(3)-synthons) have been studied in hexachlorobenzene, hexabromobenzene, pentachlorophenol, and pentabromophenol. Attention is paid to the comparison of Cl-3- and Br-3-synthons and to their competition with hydrogen bonds (HBs), based on the experimental and theoretical charge density analyses in crystal and gas phases. The main differences between Cl-3- and Br-3-synthons are established coming from the particular structure of the valence shell charge concentration region in Cl and Br atoms. Electrophilic-nucleophilic interactions take place within the intermolecular regions of Hal(3)-synthons by putting face-to-face charge depletion (CD) and charge concentration (CC) regions belonging to the valence shell of the halogen atoms. The electrostatic interaction follows the electrophilic and nucleophilic power of these regions and is monitored by the negative Laplacian values normalized to charge density unit (L/rho) at the corresponding topological critical points (CPs) of the L(r) = -del(2)rho(r) function. According to the topological and energetic properties at CPs of p(r) and L(r), it is observed that Hal(3)-synthons can successfully compete with intermolecular HBs in the analyzed structures. On the basis of the estimated interaction energy and the electrostatic descriptor Delta(L/rho) = (L/rho)(CC) - (L/rho)(CD), we conclude that a strong dispersion contribution assists Hal3-synthons in this competition.