Super-fine Conformational Analysis of Organic Molecules based on the Temperature Variable Rare Gas Matrix Isolation Method

基于变温稀有气体基质分离法的有机分子超精细构象分析

基本信息

批准号：
12640520
负责人：
YOSHIDA Hiroshi
金额：
$ 2.43万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Conformational Stabilization of 1-Methoxy-2-(methylthio)ethane by an Intramolecular CH…O Attractive Interaction : Temperature-variable Matrix-isolation Infrared Spectroscopic Study with Density Functional Theory. Intramolecular 1,5-CH…O interaction in 1-methoxy-2-(methylthio)ethane have been studied by matrix-isolation infrared spectroscopy and density functional theory. In an argon matrix, the conformer with trans-trans-gauche^±(TTG) around the CH3O-CH2-CH2-SCH3 bonds is the most stable and the conformer with TGG' is the second most stable. The energy difference between the TGG' conformer and the TTG conformer is estimated at only 0.69±0.10 kJ mo^<-1> by analysing the area intensity ratio of the spectra measured with temperature-variable matrix-isolation infrared spectroscopy. The Conformational stability and energy difference calculated by density functional theory are consistent with these experimental results.A New Approach to Vibrational Analysis of Large Molecules by Density Functional Theory : Wavenumber-Linear Scaling Method. Normal vibration calculations were performed on 164 basic organic and inorganic compounds by the density functional method of B3LYP/6-311+G** using the wavenumber-linear scaling (WLS) method, in which essentially only one parameter is involved for the whole wavenumber region. The average deviation of the WLS-scaled calculated wavenumbers from the observed wavenumbers for a total of 1223 normal modes was 3.4%. The effect of vibrational anharmonicity on the observed wavenumbers was examined on the basis of the calculated wavenumbers for 224 diatomic molecules and ions in comparison with their experimental harmonic wavenumbers. The results indicate that the more deviations upward of the unsealed calculated wavenumbers from the observed values at higher wavenumbers are attributed almost exclusively to the neglect of vibrational anharmonicity in the calculated wavenumbers.

通过分子内 CH…O 吸引相互作用实现 1-甲氧基-2-(甲硫基)乙烷的构象稳定性：1-甲氧基-中分子内 1,5-CH…O 相互作用的温变基质隔离红外光谱研究。通过基质隔离红外光谱和密度泛函理论对2-(甲硫基)乙烷进行了研究。在氩基质中，CH3O-CH2-CH2-SCH3 键周围具有 trans-trans-gauche^±(TTG) 的构象异构体是最稳定的，具有 TGG' 的构象异构体是第二稳定的。TGG' 构象异构体之间的能量差。通过分析变温矩阵隔离测量的光谱面积强度比，估计 TTG 构象异构体仅为 0.69±0.10 kJ mo^<-1>密度泛函理论计算的构象稳定性和能量差与这些实验结果一致。密度泛函理论振动分析的新方法：波数线性标度法对164种基本有机物进行了振动计算。和无机化合物通过 B3LYP/6-311+G** 的密度泛函方法使用波数线性标度 (WLS) 方法，其中基本上只涉及一个参数整个波数区域的 WLS 标度计算波数与总共 1223 个简正模的观测波数的平均偏差为 3.4%。根据 224 个计算波数检验了振动非谐性对观测波数的影响。双原子分子和离子与其实验谐波波数的比较结果表明，未密封计算的波数与观测值的偏差越大。波数几乎完全归因于计算波数中振动非谐性的忽略。