2,3-二氰基-2,3-二(p-取代苯基)丁二酸二乙酯的分子结构和晶体结构  

Crystal and Molecular Structures of meso-and dl-Diethyl 2,3-Dicyano-2,3-di(p-substituted phenyl)succinates

作　　者：杨第伦[1] 齐陈泽[1] 祝英[1] 王欣[1] 刘有成[1] 

机构地区：[1]兰州大学化学系,兰州730000

出　　处：《化学学报》1991年第12期1457-1466,共10页Acta Chimica Sinica

摘　　要：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 crystal and molecular structures of meso-and dl-diethyl 2,3-dicyano-2,3-di(p-X substituted.phenyl)succinates(X=OCH_3,meso-1,dl-1′;X=CH_3 meso-2,dl-2′;X=Cl,meso-3,dl-3′)were determined.meso-1 decomposed when its data of diffractionintensity was beening collected.dl-1′,C_(24)H_(24)N_2O_6,space group P2_1/c,a=1.7296(1),b=1.5394(1),c=0.8916(1)(nm);β=104.24(2)°,Z=4,V=2.3010(nm)~3,μ(MoKα)=0.853cm^(-1),D_c=1.260g/cm^3,final R=0.0413 for 2488 observed reflections.meso-2,C_(24)H_(24)N_2O_4,space group PⅠ,a=0.9315(1),b=0.9390(1),c=1.3241(2)(nm);α=84.39(1);β=99.38(1);γ=105.46(1)°;Z=2,V=1.0995(nm)~3μ(CuKα)=6.439 cm^(-1),D_c=1.222g/cm^3,final R=0.0501 for 2191 observed reflections.dl-2′,C_(24)H_(24)N_2O_4,space group PⅠ,a=0.9006(1),b=1.1763(1),c=1.4179(2)(nm);α=111.51(1),β=95.07(1),γ=100.37(1)°,Z=2,V=1.3549(nm)~3,μ(CuKα)=43.565cm^(-1),D_c=1.412g/cm^3,final R=0.0804 for 3049 observed reflections.meso-3,C_(22)H_(18)Cl_2N_2O_4,space group P2_1/c,a=0.8035(1),b=1.0004(1),c=1.3216(1)(nm);β=85.01(1)°;Z=2,V=1.0583(nm)~3,μ(CuKα)=30.662cm^(-1),D_c=1.397g/cm^3,final R=0.0585 for 1460 observed reflections.dl-3′,C_(22)H_(18)Cl_2N_2O_4,space group P2_1/c,a=1.3901(1)b=1.8152(1),c=0.8824(1)(nm);β=100.33(1)°,Z=4,V=2.1905(nm)~3μ(CuKα)=29.629cm^(-1),D_c=1.350g/cm^3,final R=0.0521 for 2347 observed reflections.The most important information obtained is that,in comparsion with normalC—C single bond(0.1544nm),the bond length for the central C—C bond in all of thediastereoisomers shows a remarkable lengthening effect of 0.0023—0.0052(nm)(1.4—3.4%).The bond length for the central bonds in all of meso-isomers is longer thanthat in corresponding dl-isomers.It is also observed that,among the substitutedgroups attached to the two central carbon atoms in the molecules of all of thediastereoisomers respectively,the interatomic distance between nonbonded atoms issmaller than the sum of Van der Waals radii,indicating the existence of serioussteric hindrance which is mainly reposible for the lengthening eff

关 键 词：丁二酸二乙酯 衍生物 引发剂 结构 

分 类 号：TQ314.241[化学工程—高聚物工业]