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以X射线晶体结构分析方法测定了2,3-二氰基-2,3-二(p-X 取代苯基)丁二酸二乙酯(X=OGH_3,CH_3和 Cl)的两种异构体的晶体结构和分子结构.确定了高熔点者为 dl-异构体,低熔点者为meso-异构体.观察到的重要结构信息是,这些分子内存在着显著的空间阻碍,中心 C—C 键的键长有明显的键长增长效应,而且 meso-异构体的键长增长效应比 dl-异构体更大.
The two isomers of 2,3-dicyano-2,3-bis (pX-substituted phenyl) succinic acid diethyl ester (X = OGH_3, CH_3 and Cl) were determined by X-ray crystallographic analysis Crystal Structure and Molecular Structure It has been determined that the higher melting point is the dl-isomer and the lower melting point is the meso-isomer. The important structural information observed is that these molecules present a significant steric hindrance within the center C-C The bond length of the bond has obvious effect of bond length growth, and the bond length growth effect of the meso-isomer is larger than that of the dl-isomer.