A new aromatic probe — The ring stretching vibration Raman spectroscopy frequency

• Raman frequency of breather mode determine aromaticity size of molecules.
• Aromaticity of the molecule and Raman frequency show high-positive correlation.
• Ring stretching A1g/A1′ mode of target aromatic is a single, very strong scattering.

A new aromatic criterion is presented to determine the aromatic degree of the high symmetric molecules. Group theory is used to explain the correlation between the aromatic degree and the value of Ring Stretching Vibration Raman Spectroscopic Frequency (RSVRSF). The calculations of the geometrical optimization, nucleus-independent chemical shifts (NICS) and values of the Raman Spectroscopy for the aromatic molecules—LnHn (L = C, Si, Ge, n = 3, 5–8) were performed using the Density Functional Theory (DFT) Method, as well as the correlations between the values of their RSVRSF and NICS values by Statistic Package for Social Science (SPSS17.0). There are high positive correlations between the theoretical calculated the NICS values and the value of the RSVRSF (A1g/A1′) of the LnHn (L = C, Si, Ge, n = 3, 5–8). The bigger the aromatic degree, the bigger the RSVRSF is. The value of the RSVRSF is a new probe of aromaticity. Expectedly, it is predicted that the experimental determination of the aromatic degree can be achieved by the determination of the ring stretching vibration (A1g/A1′) Raman spectrum frequencies for the aromatic target molecules.

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