The vibrational analysis of styrene, revisited

In this report we present a new proposal of vibrational analysis for the styrene molecule on the basis of an a priori scaled force field and a comparison between calculated infrared intensities and experimental absorbances. This has been done in order to clarify some discrepancies appearing in previous assignments for ν27,ν31,ν32,ν34 and ν38 modes. As experimental data we have used new IR and Raman spectra recorded at room temperature. The force field has been built up using as scale factors the arithmetic mean of those obtained for 3-fluoro, 4-fluoro, 3-chloro and 4-chlorostyrene. The root-mean-square deviation (rms) between experimental and calculated wave numbers turns out to be 6.7 cm−1, which demonstrates the reliability of the methodology used.