Intermolecular correlations of racemic mixtures – comparison between liquid S2Cl2 and Se2Br2
Intermolecular correlations of racemic mixtures – comparison between liquid S2Cl2 and Se2Br2
复制标题
外消旋混合物的分子间相关性
DOI：
10.1080/00268976.2015.1100345
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S. Takeda & S. Ohno
中科院分区：
文献类型：
--
作者：
H. Shimakura;Y. Kawakita;S. Ohmura;K. Ohara;S. Takeda & S. Ohno
液体硫属元素-卤素A2 X2（A：S，Se，X：Cl，Br）是左旋（L）和右旋（D）手性分子之间的对映异构体的外消旋混合物。硫族原子的孤对轨道对分子构象和分子间相互作用有重要影响。后者取决于轨道的大小和数密度。高能X射线衍射测量和反向蒙特卡罗（RMC）结构建模进行液体S2 Cl 2除了以前的结构分析液体Se 2Br 2。通过比较RMC模型和硬球蒙特卡罗（HSMC）模型的结构，分析了加细对实验结构因子的影响。本文根据对映体对的不同，将最近邻分子间对分为L-L和D-D对映体对和L-D对映体对。结果表明，Se_2Br_2中的分子间吸引作用使HSMC与RMC之间具有几何优势的类对数目增加，而S_2Cl_2中的分子间排斥作用使HSMC与RMC之间的平均分子间S-S距离延长.这些结果与Se_2Cl_2和S_2Cl_2的从头算分子动力学模拟结果一致。
Liquid chalcogen-halogen A2X2(A: S, Se, X: Cl, Br) is a racemic mixture of enantiomers between left-handed (L) and right-handed (D) chiral molecules. The lone-pair orbital of the chalcogen atom significantly affects the molecular conformation and intermolecular interaction. The latter depends on the size of the orbital and number density. High-energy X-ray diffraction measurements and reverse Monte Carlo (RMC) structural modelling were performed for liquid S2Cl2in addition to the previous structural analysis for liquid Se2Br2. By comparing the structures of the RMC model and hard-sphere Monte Carlo (HSMC) model, the effect of refinement on the experimental structure factor can be analysed. In this paper, nearest-neighbour intermolecular pairs are classified in terms of enantiomer pairs such as like-pair (L-L and D-D) and unlike-pair (L-D). As a result, the effect of a strong intermolecular attractive interaction is detected in Se2Br2as increasing the number of like-pairs with geometrical advantages from HSMC to RMC, whereas that of an intermolecular repulsive interaction is observed in S2Cl2as elongation of the averaged intermolecular S-S distance from HSMC to RMC. These results are consistent with the results of theab initiomolecular dynamics simulation for Se2Cl2and S2Cl2.