CRYSTAL AND MOLECULAR STRUCTURES OF TWO ISOMERS OF DIETHYL 2, 3-DICYANO-2, 3-DIPHENYLSUCCINATE

• 作 者: 刘有成 杨第伦 杨清传 韩玉真 邵美成 唐有祺
• 机 构: Department of Chemistry, Lanzhou University,Department of Chemistry, Lanzhou University,Institute of
• 出 处: Science in China,Ser.B
• 发表日期: 1986年10期
• 关键词: polymerization substituent initiator dissociation crystalline steric facile atta

Diethyl 2, 3-dicyano-2, 3-diphenylsuccinate was prepared through the oxidative coupling of ethyl α-cyanophenylacetate with Cu~(++)-TMEDA-O_2 system. The product gave, upon chromatography, two crystalline compounds 1 and 2. The single crystals of 1 and 2 were identified by X-ray crystallographic analysis to be meso-and racemie-diethyl 2,3-dicyano-2,3-diphenylsuccinate respectively. It is noteworthy that in the molecules of 1 and 2 there is a remarkable lengthening effect of the bond length for the central C—C bond, i. e. 1: 1.585; 2: 1.62. It is also observed that there is steric hindrance between the substituent groups attached to the two carbon atoms of the central C—C bond respectively. These data provide the structural basis for the facile dissociation into radicals and the action of polymerization initiator of the title compound. CNDO/2 calculation of charge density and Wiberg bond order for compound 1 yields the results, which are consistent with the crystallographic data.