Calculated infrared absorption and vibrational circular dichroism intensities of oxirane and its deuterated analogues
Calculated infrared absorption and vibrational circular dichroism intensities of oxirane and its deuterated analogues
复制标题
计算环氧乙烷及其氘代类似物的红外吸收和振动圆二色性强度
DOI：
10.1021/ja00200a010
复制
发表时间：
1989
影响因子：
15
通讯作者：
A. Rauk
中科院分区：
文献类型：
--
作者：
R. Dutler;A. Rauk
本文用从头算方法计算了（S）-2-氘代环氧乙烷、（S，S）-2，3-二氘代环氧乙烷和（S）-2，2，3-三氘代环氧乙烷的振动圆二色性（VCD）强度。发现该理论再现公布的（S，S）-2，3-二氘环氧乙烷的光谱特征非常好，如果基组包含的基础函数的正常集的衍生物。在6- 3lg基组的基础上，提出了一个合适的基组，命名为6 - 31 g（-2s，2 p，2 pH）。发现6- 31 g（-2s，2 p，2 pH）基组产生的环氧乙烷的几何构型比通过用六倍大小的6- 31 G ** 组优化获得的更接近微波结构。6-3 lg（-2s，2 p，2 pH）力常数的均匀标度或有限的非均匀标度允许与观察到的环氧乙烷和四氘环氧乙烷的振动频率极好的一致性（< 1%误差）。这两种化合物的红外光谱强度也与实测值相当吻合。以不均匀的方式缩放的力常数计算的IR强度有轻微的不利影响，这表明从头算正常模式可能是优选的。本文用声振耦合理论对由Freedman和Shakafie提出的VCD光强的APT理论进行了检验。从头算原子极性张量，准确地再现环氧乙烷和DT物种的红外光谱。APT理论被发现有很小的预测能力，除了可能在CD和CH伸缩区的光谱。预测了所有氘代环氧乙烷同位素异构体的全红外光谱和所有手性物种的VCD光谱。
An ab initio implementation of the vibronic coupling theory of Ñafie and Freedman is described and applied to the computationof vibrational circular dichroism (VCD) intensities of (S)-2-deuteriooxirane,(S, S)-2, 3-dideuteriooxirane, and (5)-2, 2, 3-trideuteriooxirane. The theory is found to reproduce the published spectral features of (S, S)-2, 3-dideuteriooxirane very well if the basis set incorporates derivatives of the normal set of basis functions. A suitable basis set, based on the standard 6-3 lg set and designated6-31g (-2s, 2p, 2pH), is proposed. The 6-31g (-2s, 2p, 2pH) basisset is found to yield a geometry for oxirane that is closer to the microwave structure than obtained by optimization with the comparably sized 6-31G** set. Uniform scaling or limited nonuniform scaling of the 6-3 lg (-2s, 2p, 2pH) force constants permit excellent agreement (< 1% error) with observed vibrational frequencies of oxirane and tetradeuteriooxirane. Quite satisfactory agreement with the measured IR intensities for these two compounds is also obtained. Scaling of the force constants in a nonuniform manner has a slightly adverse effect on calculated IR intensities, suggesting that the ab initio normal modes may be preferable. The APT theory of VCD intensities introduced by Ñafie and Freedman has been tested against the vibronic coupling theory. Ab initio atomic polar tensors that accurately reproduce the IR spectrum of oxirane and the dt species were employed. The APT theory was found to have little predictive capability except possibily in the CD and CH stretching region of the spectrum. The full IR spectra of all of the deuterated isotopomers of oxirane and the VCD spectra of all of the chiral species are predicted.