N-芳酰基-N′-芳基-S-甲基异硫脲类化合物的红外光谱

AN INVESTIGATION ON THE IR SPECTRA OF N-AROYL-N^(?)-ARYL-S-M ETHYL ISOTHIOUREAS

在N-芳酰基-N′-芳基-S-甲基异硫脲类化合物,R=H或CH_3的红外光谱中均表现出异常低的υc=o吸收,合成了九个类似物,对其中的N-苯甲酰基-N′-甲基-N′-苯基-S-甲基异硫脲和N-苯甲酰基-N′-对氯苯基-S-甲基异硫脲进行了X射线单晶衍射测定。从结晶数据中看出,基本上处在同一平面,C—N和C=N键的键长起了平均化作用因此,影响羰基红外吸收的主要因素是共轭效应。

Nine N-aroly-N'-aryl-S-methyl isothioureas have been synthesized and the IR spectra of all nine compounds showed extraordinary low ν_(c-o) absorption. Among them, N-benzoyl-N'-methyl-S-methyl isothiourea and N-benzoyl-N'-(4-chlorophenyl)-S-methyl isothiourea have been studied with single crystal X ray diffraction. It is found that, from the crystallographic data, the bond lengths C=N and C—N have been averaged and the atoms of phC (O)=N=C—N—are nearly on the same plane. Thus the main effect to influence the IR absorption of carbonyl group is conjugation.