Molecular structure, vibrational spectroscopic studies and analysis of 2-fluoro-5-methylbenzonitrile

Quantum mechanical calculations of energies, geometries and vibrational wavenumbers of 2-fluoro-5-methylbenzonitrile (2F5MBN) have been carried out by using density functional theory (DFT/B3LYP) method with 6-311++G(d,p), cc-pvdz, Aug-cc-pvdz as basis sets. The optimized geometrical parameters obtained by DFT calculations are found to be in good agreement with experimental X-ray data. The best level of theory in order to reproduce the experimental wavenumbers is B3LYP method with the 6-311++G(d,p) basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. A detailed interpretation of the infrared and Raman spectra of 2F5MBN has also been reported. The entropy of the compound under study is also performed at /B3LYP/ 6-311++G(d,p), cc-pvdz, Aug-cc-pvdz levels. The theoretical spectrogram for FT-IR and FT-Raman spectra of the molecule have been constructed.