[η5-C5X5]-（X=H,F～Br）的芳香性及其与拉曼光谱的相关性

Correlation between the ring stretching vibration Raman spectroscopic frequency and aromaticity for [η5-C5X5]-（X=H,F～Br）

寻找实验上定量测定芳香性物质芳香性大小的方法是科学家一直追求的一个目标。本研究采用Gaussian09计算程序中的密度泛函理论（DFT）,对[η5-C5X5]^-（X=H,F-Br）进行几何结构优化,核独立化学位移（NICS）值及环伸缩振动拉曼光谱频率（RSVRSF）大小进行了理论计算。结果表明：取代环戊二烯基负离子的NICS值均为负值,均为芳香性的,其中均存在A1＇对称性的RSVRSF,其NICS绝对值、RSVRSF值均随着F、Cl、Br取代的顺序逐渐减小,呈高度正相关,且相关性系数均达到0.99以上,理论预测可通过实验测定其RSVRSF值测定该类物质的芳香性大小。

It is a pursuing goal to find an experimental method of determining the aromatic size of aromatic substances for scientists. The calculations for the geometries optimization, nucleus independent chemical shifts（NICS） and values of the Raman spectroscopy for [η5-C5X5]-（X=H,F-Br） were conducted using density functional theory（DFT） method within Gaussian09 process package. The results show that, for the [η5-C5X5]-, the values of NICS were all negative. These kinds of substances were all aromatic. There were Ring Stretching Vibration Raman Spectroscopic Frequency（RSVRSF） peaks with A1＇ symmetric in the [η5-C5X5]-. The RSVRSF values and the absolute NICS values of the [η5-C5X5]^-gradually decreased with the order of F, Cl, and Br, showing a highly positive correlation, and the correlation coefficients were above 0.99. It is theoretically predicted that the determination of the aromatic degree is possible by the experiment determination of the RSVRSF values for the [η5-C5X5]-.