烃类化合物碳氢键解离焓的密度泛函理论研究  

C—H Bond Dissociation Enthalpies of Hydrocarbons by Density Functional Theory Studies

作　　者：郑文锐[1] 傅尧[1] 王华静[1] 郭庆祥[1] 

机构地区：[1]中国科学技术大学化学系,合肥230026

出　　处：《有机化学》2008年第3期459-466,共8页Chinese Journal of Organic Chemistry

基　　金：国家自然科学基金(No.20602034);安徽省自然科学基金(No.070416237)资助项目

摘　　要：通过比较10种密度泛函方法对烃类化合物碳氢键解离焓的计算精度,发现新型密度泛函BMK方法具有最高的计算精度.利用该方法计算了包含饱和链烃,、不饱和链烃、脂环烃和芳香烃在内的172个烃类化合物的碳氢键解离焓,计算均方根误差仅为7.95kJ·mol-1,线性拟合常数为0.985.通过自然键轨道法分析发现,烃类物质的碳氢键解离焓与母体的碳氢键杂化轨道成分p%,自由基奇电子轨道杂化成分p%及自由基的自旋密度三个参数之间存在较好的定量关系.此外,饱和链烷烃及不饱和链烃的碳氢键解离焓与碳氢键键长之间也存在较好的线性关系.Ten density functional theory （DFT） methods were compared for calculating the carbon-hydrogen bond dissociation energies of hydrocarbons. It was found that the newly developed DFT method BMK gave the best results. Subsequently the carbon-hydrogen bond dissociation enthalpies of 172 hydrocarbons including alkanes, unsaturated chain hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons were calculated systematically using the BMK method. The root of mean square error was as low as 7.95 kJ·mol^-1 and the correlation coefficient was 0.985. The natural bond orbital （NBO） analysis revealed that the C-H bond dissociation enthalpies （BDEs） of hydrocarbons were dependent on the hybridization of the parent compound, the hybridization of the radical, and the spin density of the radical. A good quantitative relationship among BDEs and the three parameters was found. Furthermore, a good correlation was observed between the carbon-hydrogen bond lengths and the C-H BDEs of alkanes as well as unsaturated hydrocarbons.

关 键 词：键解离焓 密度泛函方法 自然键轨道分析 烃类化合物 

分 类 号：O621.1[理学—有机化学]