Abstract

Density functional theory and vibrational analysis of Methyl Phenoxy Acetic Acid herbicide has been carried out using FT-IR spectroscopic technique and compared with computational technique. The FT-IR spectra have been recorded in the region 400–4000 cm?1. The geometry has been optimized with complete relaxation on the potential energy surface at B3LYP level of theories using 6-311G (d,p) basis set using Gaussian 09 program and compared with the crystal data. Further, harmonic vibrational frequency calculations have been carried out at B3LYP level and the scaled values were in good agreement with majority of the experimental observations. The theoretically constructed spectra coincide satisfactorily with those of experimental spectra. The relative energies, NBO analysis and structural parameters predicted that steric effect determine the stabilization of the compound. Theoretical methods have been used to study the proper and improper hydrogen bonds, considering the hydrogen bond length and charge transfer. The NBO analysis showed the intra and intermolecular C-H…O hydrogen bonds in the crystal structure of Methyl Phenoxy Acetic Acid Herbicide.