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应用LDA-PWC方法对亚碘酰苯低聚物HO-(PhIO)n-H(n=1～10)(链末端以羟基结束)共10个模型分子进行了理论研究.计算结果表明PhIO分子链大致呈“T”形,I—O链的两个I—O键键长非常接近,同时发现I—O链产生扭转,整个亚碘酰苯低聚物呈螺旋状结构.应用B3LYP法得到HO-(PhIO)6-H更为精确的亚碘酰苯低聚物稳定构型,平均I—O键长为0.2089nm,标准偏差为0.0007nm.理论计算表明在600～400cm-1段,PhI18O的吸收峰向低波数方向移动,与实验观测结果一致.振动模式分析发现该段吸收峰均涉及氧原子,18O同位素效应将降低各振动峰值的频率.峰值移动最大的吸收峰为591/566cm-1(16O/18O),与之对应的理论计算值为590.409/557.788cm-1(16O/18O),属于对称伸缩振动ν(I—O—I).吸收峰(443/436cm-1)对应的理论计算值为460.627/439.158cm-1(16O/18O),归属于不对称伸缩振动ν(I—O—I)。
A theoretical study of 10 model molecules of HO-(PhIO) nH (n = 1-10) terminated by hydroxyl group using LDA-PWC method was carried out. The calculation results show that the molecular chain of PhIO The I-O bond length of the I-O chain is very close, and the I-O chain is found to be twisted, and the entire iodosobenzene oligomer has a helical structure. The B3LYP method is used to obtain HO- (PhIO) 6-H is a more accurate stable structure of iodosobenzene oligomers with an average I-O bond length of 0.2089 nm and a standard deviation of 0.0007 nm. Theoretical calculations show that at 600-400 cm -1, The absorption peak of PhI18O shifted to the low wavenumber direction, which was in good agreement with the experimental results. The vibrational mode analysis showed that the absorption peak of this phase involved oxygen atoms and the 18O isotope effect would reduce the frequency of each vibration peak. The peak peak absorption peak was 591 / 566cm (16O / 18O), corresponding to the theoretical calculated value of 590.409 / 557.788cm-1 (16O / 18O), belongs to the symmetrical stretching vibration ν (I-O-I) absorption peak (443 / 436cm-1) The corresponding theoretical value is 460.627 / 439.158cm-1 (16 / 18O), belonging to the asymmetric stretching vibration ν (I-O-I).