超共轭效应与甲砜的红外特征峰及有关芳砜的晶体结构

文章分为三部分：第一部分，描述通过四圆衍射仪，利用Ｘ射线单晶衍射法，所测得的芳砜ＣＨ３ＣＯＮＨ－Ｃ６Ｈ４－ＳＯ２Ｒ（Ｒ＝－ＣＨ３，－ＣＨ２ＣＯＮＨ２，－ＣＨ２ＣＨ２ＯＨ）的晶体及分子结构结果：第二部分，对分子内键角和键长的测试结果进行分析，证明了甲砜分子内超共轭效应的存在，解释了甲砜分子红外吸收的异性是由甲砜基团内超共轭效应引起的，找到了认证甲砜的红外特征峰，并揭示了超共轭效应的某些特性；第三部分

Hyperconjugation, Characteristic Infrared Absorption of Methylsulfones and Crystal Structures of Selected Aromaticsulfones

A branched absorption peak with medium intensity at (970 +/- 20) cm-1 appears only in the infrared spectra of methylsulfones. The below mentioned aromaticsulfones are chosen to reveal the specificity. Crystal and molecular parameters of CH3CONH-C6H4-SO2R(R = -CH3, -CH2CH2OH)-CH2CONH2, are determined by application of single crystal diffraction of X-ray through Nicolet R3M/E diffracometer. The existence of hyperconjugation and its natures in group -SO2CH3, confirmed by further analyses on the parameters, result in the specificity of IR absorption of the group, which is proved characteristic and can be used to identify methylsulfones. The first part describes the detection results, ascertains their crystal and molecular structures, and shows that the aromaticsulfone exists as cross linking multi-molecules when R = -CH2CONH2 or as double molecules when R = -CH2CH2OH because of H bonds. The second part covers analyses on their molecular structures. The analyses demonstrate the hyperconjugation between sigma S-C and pi S-C in group -SO2CH3. The sigma C-H hyperconjugate with pi S-O. The strength of hyperconjugated bond C-H decreases and its length tends longer. Due to the effect, the bond S-C is not a pure single bond sigma, but one which possesses a certain degree of a double bond. Its IR wave number, between those of sigma S-C and pi S-C, attributes to the medium branched peak at (970 +/- 20) cm-1. The peak branch reflects two groups of the most stable hyperconjugating conformational isomers. The hyperconjugation is weakened by the substitution of one non H group for one H atom in -SO2CH3 and if the non H group does not conjugate with pi S-O, the absorption at (970 +/- 20) cm-1 disappears as a characteristic peak. The intensity of absorption at (970 +/- 20) cm-1 conforms to the intensity of hyperconjugation between pi S-O and its adjacent sigma C-H. The third part introduces syntheses of the products, crystal preparations and their detections through X-ray diffraction.