摘要
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 crystal and molecular structure of dl-diethyl-2, 3-dicyano-2, 3-di (3, 4-dimethoxyphenyl) succinate was determined and analyzed. Its data of diffraction intensity was collected :C_26H_28N_2O_8, space group P1 , Mr=496. 52, α= 12. 047(1) ,b = 13. 271 (1), c=8. 728(2) A,α=90. 71(1)°,β=108. 81(1)°,γ=84. 87(1)°, V=1315. 4(2) , Z=2, Dc=1. 254 g/cm3,μ(CuKα) =7. 42 cm-1, Rw=0. 054, final R= 0. 060 for 318l observed reflections.The important information obtained was that, in comparison with normal C-C single bond(1-544),the bond length for C(1)-C(1)'bond showed a remarkably lengthened effect of 0. 037. It was also calculated that interatomic distances between nonbouding atoms are smaller than the sum of van der Waals radii,indicating the existence of serious steric hindrance in molecule which was mainly responsible for the lengthening effect. The influence of electron offect on C(1) C(1)'bond is discussed.
基金
国家自然科学基金
关键词
氰基
甲氧基苯基
丁二酸二乙酯
晶体结构
dl-diethy1-2
3-dicyano-2
3-di(3
4-dimethoxyphenyl) succinate
crystal structure
steric effect
electron effect
