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我们曾经相继报导了(RO)_2P(S)SH类型化合物的R=Et,i-P_r两种化合物的旋转异构现象的红外及拉曼光谱的研究结果,本文将继续报导同系物R=Me的FT-IR研究结果。标题化合物按文献方法制备及提纯处理。样品的常温及低温光谱是在Nicofet5DX型FT-IR光谱仪上记录的,使用液氮作低温冷却剂。在不同温度下记录的P=S伸展振动带用计算机程序进行分峰处理,结果表明,P=S谱带仍由4个不同频率组成,这四个频率依次为671,661,655和649cm~(-1),它们对应于四个构象不同的旋转异构体。我们得到的结果是,第一,在室温到-80℃范围内,这四个异构体的P=S谱带的相对面积(S%)与温度之间的关系表明,异构体(1)与(2),(3)与(4)之间分别存在着对应相互转化关系,即异构体(1)的含量减少时,(2)便相应增加,反之亦然。(3)与(4)之间也有类似的现象。第二,O~-—R~-基的局部偶极场对P=S键的作用是一种引力场,因此构象(1)对应于四个频率中最高的671cm~(-1)带,构象(4)则对应于最低的频率649cm~(-1)。第三,由于存在S—H……S=P内氢键,因此S—H基的空间取向一旦形成,便不易改变,只有—OR基可绕O—P键旋转,所以存在异构体(1)与(2),(3)与(4)之间的相互转化关系。
We have reported the results of the IR and Raman spectra of the R = Et, i-P_r rotamers of (RO) 2P (S) SH type compounds in succession. We will continue to report the homologue R = Me FT-IR findings. The title compound is prepared and purified according to literature procedures. The normal and low temperature spectra of the samples were recorded on a Nicofet 5DX FT-IR spectrometer using liquid nitrogen as a cryogenic coolant. The P = S extensional vibration band recorded at different temperatures was subdivided by a computer program. The results showed that the P = S band was still composed of four different frequencies, which were 671, 661, 655 and 649 cm -1, , Which correspond to four different conformational rotamers. The results we obtained are, first, that the relationship between the relative area (S%) of the P = S band of these four isomers and temperature at room temperature to -80 ° C shows that isomer (1 ) And (2), (3) and (4), respectively, there is a corresponding mutual transformation relationship, that is, when the content of isomer (1) decreases, (2) will increase correspondingly and vice versa. There is a similar phenomenon between (3) and (4). Secondly, the local dipole field of O ~ - R ~ - group acts as a kind of gravitational field for the P = S bond. Therefore, conformation (1) corresponds to the highest 671cm ~ (-1) Conformation (4) corresponds to the lowest frequency of 649 cm -1. Third, due to the presence of S-H ... S = P hydrogen bonds, the spatial orientation of the S-H group is not easily changed once formed. Only the -OR group can rotate around the O-P bond, so the isomer 1) and (2), (3) and (4) of the mutual conversion relationship.