C-H键和C-C键核自旋偶合常数的理论研究  

A Theoretical Study on Nuclear Spin-Spin Coupling Constants of C-X (X=H,C) Bonds

作　　者：黄荣谊[1,2] 叶世勇[2] 

机构地区：[1]安庆师范学院化学化工学院,安徽安庆246003 [2]安徽师范大学化学与材料科学学院,安徽芜湖241000

出　　处：《波谱学杂志》2009年第3期327-334,共8页Chinese Journal of Magnetic Resonance

摘　　要：利用PM3级别最大重迭对称性分子轨道法和最大键级杂化轨道方法,计算了系列烃类化合物的杂化轨道和电荷分布,拟合出计算C-H及C-C偶合常数的简单关系式.研究了各种烃类分子中不同的C-H键和C-C键偶合常数,理论计算值和实验数据都较为符合.进一步验证了直接键连1JCX偶合常数主要取决于偶合作用中的Fermi接触项,为从简单价键理论角度解释和计算1JCH和1JCC提供了一种简便直观的方法.A theoretical model for calculating the nuclear spin-spin coupling constants of the directly-boned C--H and C--C bonds was formulated using the s-character of the hybrid orbitals and the atomic net charges as the variables. The model was applied to calculate ^1JCX（X=C, H） of a number of hydrocarbons based on the maximum overlap symmetry molecular orbital （MOSMO） method under PM3 approximation and the maximum bond order hybrid orbital （MBOHO） procedure. The calculated values were found to be in good agreement with the experimental data, supporting the notion that the Fermi contact term are a dominant factor in determining the carbon hydrogen and carbon carbon spin-spin coupling constants over one bond. The method developed provided a platform to interpret and calculate ^1JCH and ^1JCC based on simple valence bond theory.

关 键 词：核自旋偶合常数 最大重迭对称性分子轨道 PM3近似 最大键级杂化轨道 

分 类 号：O641[理学—物理化学]