Theoretical Investigation of Vibrational, Structural and Electronic Properties of N-Ethylacetanilide Using Quantum Chemical Calculation Methods

Theoretical investigation of title N-ethylacetanilide compound is carried out using density functional theory (DFT) and ab initio Hartree Fock (HF) with the B3LYP/6-31+G(d,p) level of theory. Molecular geometries, including bond lengths and bond angles, for the most optimized structure are calculated at both the HF and DFT methods, and the results show excellent agreement between two theoretical approaches. All subsequent calculations are carried out exclusively at the B3LYP/6-31+G(d,p) method, as this basis set offers a reliable description of the significant electron correlation effects observed during the computations, with the assumption that a single-level calculation is sufficient. On this basis, a comprehensive set of analyses, including detailed vibrational assignments, thermochemical properties, atomic charge distributions, UV–Vis absorption spectra, dipole moment, molecular electrostatic potential maps, electrostatic potential distributions, and frontier molecular orbital energies are carried out in the ground state by means of DFT/B3LYP/6-31+G(d,p) approach. Besides, scaled vibrational frequencies are assigned with the aid of normal coordinate analysis, and the results show excellent agreement with the obtained experimental findings, confirming the reliability of the preferred computational method. Additionally, molecular electrostatic potential (MEP), electrostatic potential (ESP) surface maps, frontier molecular orbitals (FMO), transition states, and the energy band gap are examined to provide a valuable information about electronic structure and effective reactivity of the title molecule studied. The dipole moment and charge distribution analyses revealed intermolecular interaction capabilities and potential for metallic bonding. In addition, infrared intensities and Raman activities are predicted to complement the vibrational characterization. Furthermore, total energies and dipole moments are evaluated under different polarity environments to investigate solvent–molecule interactions, providing insights into the potential application fields of the title compound. Consequently, the study not only validates the suitability of the chosen computational level for modeling this compound but also contributes to a deeper understanding of its structural, spectroscopic, and electronic features, offering valuable implications for future applications in material sciences, chemistry, biology, and industry.