Theoretical investigations of α,α,α-trifluoro-3, -p and o-nitrotoluene by means of density functional theory

This study reports the optimized molecular structures, vibrational frequencies including Infrared intensities and Raman activities, corresponding vibrational assignments, 1H and 13C NMR chemical shifts, the magnitudes of the JCH and JCC coupling constants, Ultraviolet–visible (UV–vis) spectra, thermodynamic properties and atomic charges of the title compounds, α,α,α-trifluoro-3, -p and o-nitrotoluene, in the ground state by means of the density functional theory (DFT) with the standard B3LYP/6-311++G(d,p) method and basis set combination for the first time. Theoretical vibrational spectra were interpreted by normal coordinate analysis based on scaled density functional force field. The results show that the vibrational frequencies and chemical shifts calculated were obtained to be in good agreement with the experimental data. Based on the comparison between experimental results and theoretical data, the calculation level chosen is powerful approach for understanding the identification of all the molecules studied. In addition, not only were frontier molecular orbitals (HOMO and LUMO), molecular electrostatic potential (MEP) and electrostatic potential (ESP) simulated but also the dipole moment, softness, electronegativity, chemical hardness, electrophilicity index, transition state and energy band gap values were predicted. According to the investigations, all compounds were found to be useful to bond metallically and interact intermolecularly; however, the thermodynamic properties confirm that the α,α,α-trifluoro-p-nitrotoluene was more reactive and more polar than the others.

The electrostatic potential ESP figure presents that the most negative ESP is spread over the oxygen and fluorine atoms, indicating the delocalization of π-electrons over the nitro and trifluoromethyl groups for the α,α,α-trifluoro-o-nitrotoluene. The figure also reveals the extended conjugation of the benzene ring with these groups. Furthermore, the 2D contour of total charge density of the compound studied is presented in the same figure. Based on the contour, blue color in the molecule studied is found to be the predominance because of the positive charge distribution of the title compound.Figure optionsDownload as PowerPoint slideHighlights
► This study deals with novel theoretical aspects and novel applications of the molecules.
► FMO, MEP and ESP are also performed via quantum computational methods (DFT).
► NMR and UV–vis spectra are investigated found to be in good agreement with experimental results.
► Transition state and energy band gap were determined for studies of the compounds.
► The charge transfer within the molecules is investigated by HOMO and LUMO analyses.