2-Amino-3,5-dichlorobenzonitrile: DFT calculations in the monomer and dimer forms, FT-IR and FT-Raman spectra, molecular geometry, atomic charges and thermodynamical parameters

• The Raman and IR spectra of 2-amino-3,5-dichlorobenzonitrile in the solid state were simulated.
• The simulation was carried out with four dimer forms.
• An accurate scaling procedure was used to improve the calculated wavenumbers.
• Dimer B is the expected form in the crystal with wavenumbers close to the experimental.
• The NH2 group produces higher change on the geometry than the chlorine atoms.

The experimental IR and Raman spectra of 2-amino-3,5-dichlorobenzonitrile molecule were recorded, and the results compared with theoretical values. Molecular geometry, vibrational wavenumbers and thermodynamic parameters were calculated using MP2 and DFT quantum chemical methods. With the help of specific scaling procedures for the computed wavenumbers, the experimentally observed FTIR and FT-Raman bands were analyzed and assigned to different normal modes of vibrations of the molecule. Simulations in the dimer form were carried out to improve the assignment of the bands in the solid state experimental spectra. The error obtained was in general very low. Using PED’s were determined the contributions of the different modes to each wavenumber. Several general conclusions were also deduced.

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