大学化学 >> 2023, Vol. 38 >> Issue (8): 305-311.doi: 10.3866/PKU.DXHX202209041

师生笔谈 上一篇    下一篇

浅谈环张力对C=C及C=O双键红外吸收频率的影响

郭艳春, 王慧婷, 魏东辉, 陈晓岚, 曹书霞()   

  • 收稿日期:2022-09-19 录用日期:2022-12-02 发布日期:2023-01-06
  • 通讯作者: 曹书霞 E-mail:csx@zzu.edu.cn
  • 基金资助:
    2020年度郑州大学校级一流本科课程重点项目;2020年河南省研究生教育优质课程项目

Brief Discussion of the Influence of Ring Strain on Infrared Absorption Frequencies of C=C and C=O Double Bonds

Yanchun Guo, Huiting Wang, Donghui Wei, Xiaolan Chen, Shuxia Cao()   

  • Received:2022-09-19 Accepted:2022-12-02 Published:2023-01-06
  • Contact: Shuxia Cao E-mail:csx@zzu.edu.cn

摘要:

红外光谱是大学波谱分析课程教学的重要内容之一,而环张力对红外吸收频率的影响则是其中的难点。现有的教材没有对此进行严谨和详尽的解释,使得学生在接受环张力对基团红外振动频率影响的结论时仍然会感到困惑。本文运用密度泛函理论(DFT),在全优化分子结构的基础上,计算出相关化合物的张力能、化学键的键长、键角、振动频率以及轨道成分。基于DFT计算结果,详尽合理地解释了环张力是如何影响C=C及C=O双键的振动频率。

关键词: 红外光谱, 环张力, 振动频率, 密度泛函理论, 振动耦合

Abstract:

Infrared spectroscopy is an important content of a college course "spectroscopy analysis", and the understanding of the influence of ring strain on infrared absorption frequency is a challenge. No rigorous and detailed explanation on this exists in the current textbooks, making students still confused when they accept the conclusion of the influence of ring strain on infrared vibrational frequency. Here, we use the density functional theory (DFT) to calculate the strain energy, bond length, bond angle, vibrational frequency, and orbital proportion of related bonds based on the fully optimized molecular structure. Based on the results of DFT calculation, the effect of ring strain on the vibrational frequencies of C=C and C=O double bonds is explained reasonably and in detail.

Key words: Infrared spectroscopy, Ring strain, Vibrational frequency, Density functional theory, Vibrational coupling