拉曼光谱测定C_6X_6(X=F,Cl,Br)芳香性大小的理论研究

Theoretical predictions on raman spectrum determine aromaticity degree of C_6X_6(X=F, Cl, Br)

采用Gaussian09软件,运用密度泛函理论方法(B3LYP/6-311+g(d,p))对C_6X_6(X=F,Cl,Br)分子进行几何优化、芳香性大小,拉曼光谱进行研究。研究发现,C_6X_6(X=F,Cl,Br)是高对称的平面几何结构,芳香性依次减小。采用社会科学统计软件包(SPSS)对计算结果进行分析,表明NICS理论计算数值与其RSVRSF理论计算数值间存在高度负相关,同时C_6X_6(X=F,Cl,Br)的拉曼光谱图表明环伸缩振动(A_(1g))有明显的强峰。所以实验上可以通过测定C_6X_6(X=F,Cl,Br)的RSVRSF大小实现对其芳香性大小测定。

The geometrical optimization, nucleus-independent chemical shifts（NICS） and Roman Spectroscopy of C_6X_6（X=F, Cl,Br） were studied using the Density Functional Theory（DFT） Method（B3LYP/ 6-311＋g（d, p））. The calculation results show structures of C_6X_6（X=F, Cl, Br） are plane and the aromaticity degree of C_6X_6（X=F, Cl, Br） continuously decrease. The correlations between the values of their RSVRSF and NICS values by Statistic Package for Social Science（SPSS17.0）. There are highly correlations between the theoretical calculated values NICS and RSVRSF（A_（1g）） of the C_6X_6（X=F, Cl, Br）. Raman spectrum show very strong scattering that mainly originates from ring stretching vibration（A_（1g））. Therefore, it is possible to test aromaticity degree of C_6X_6（X=F, Cl, Br） via testing the RSVRSF（A_（1g）） value experimentally and quantitatively.