Molecular structure, vibrational spectra and NBO analysis on 1N-acetyl-3-(2, 4dichloro-5-fluoro-phenyl)-5-(<i style="">p</i>-methyl-phenyl)-2-pyrazoline using DFT method

Abstract

Quantum chemical calculations of molecular geometry, harmonic vibrational frequencies and bonding features of 1N-acetyl-3-(2,4-dichloro-5-fluoro-phenyl)-5-(<i style="">p</i>-methyl-phenyl)-2-pyrazoline (C₁₈H₁₅Cl₂FN₂O) in the ground state have been carried out by using density functional theory (DFT/B3LYP) method with 6-311++G** basis set. Theoretical vibrational spectra of the title compound have been interpreted by means of PEDs using MOLVIB program. The theoretical spectrograms for IR and Raman spectra of the title compound have been constructed.<b style=""> </b>Stability of the molecule arising from hyper conjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Natural bond orbital analysis shows that there exists C-H…Cl hydrogen bond in the title compound, which is consistent with the conclusion obtained by the analysis of molecular structure. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule.