论文部分内容阅读
用Ｘ射线晶体结构分析法测定和分析了ｄｌ－２，３－二氰基－２，３－二（３，４－二甲氧基苯基）丁二酸二乙酯的分子结构和晶体结构。晶体学数据据为：Ｃ２６Ｈ２８Ｎ＿２Ｏ＿８，Ｍ＿ｒ＝４９６．５２，空间群Ｐ１，α＝１２．０４７（１），ｂ＝１３．２７１（１），ｃ＝８．７２８（２），α＝９０．７１（１），β＝１０８．８１（１），γ＝８４．８７（１）°，Ｖ＝１３１５．４（２），Ｚ＝２，Ｄ＿ｃ＝１．２５４ｇ／ｃｍ￣３。晶胞内两个分子分别为具有Ｒ─Ｒ构型和Ｓ─Ｓ构型的手性分子。分子结构分析表明分子内有许多非键连原子间距小于ｖａｎｄｅｒＷａａｌｓ半径和。基团间的空间排斥作用使两苄碳原子间的σ键键长较正常的碳－碳单键明显增长，且分子内电子效应对上述σ键的变化亦有较大的影响。
The molecular structure and crystal structure of dl-2,3-dicyano-2,3-bis (3,4-dimethoxyphenyl) butanedioic acid diethyl ester were determined and analyzed by X-ray crystal structure analysis . The crystallographic data were as follows: C26H28N_2O_8, M_r = 496.52, space group P1, α = 12.047 (1), b = 13.271 (1), c = 8.728 (2), α = 90.71 (1), β = 108.81 (1), γ = 84.87 (1) °, V = 1315.4 (2), Z = 2 and D c = 1.254 g / cm 3. The two molecules in the unit cell are chiral molecules with R-R configuration and S-S configuration, respectively. Molecular structure analysis shows that there are many unbonded atoms in the molecule with a spacing less than the van der Waals radius. The steric exclusion between groups makes the σ bond length between two benzylic carbon atoms increase obviously compared with normal carbon-carbon single bond, and the intramolecular electron effect also has a great influence on the above σ bond change.