Scaled quantum mechanical force field of dimethylpyrazines: vibrational assignments

The infrared and Raman spectra of 2,3-dimethyl, 2,5-dimethyl and 2,6-dimethylpyrazine have been recorded. The calculated ab initio wavenumbers have been adjusted to the experimental ones by using the scaled quantum mechanical force field (SQMFF) methodology which allows the transference of the scale factors from structurally related molecules. In this work, the scale factors corresponding to the aromatic ring and the methyl group have been transferred from the force fields of pyrazine and 2-methylpyrazine, respectively. A complete vibrational assignment of these methylderivatives has been proposed.