VIBRATIONAL SPECTROSCOPIC STUDY OF PYRIDINE AND PYRIMIDINE LIGANDS COORDINATED WITH ANTIMONY (III) COMPLEXES: INSIGHTS FROM DFT CALCULATIONS

Abstract

By employing the Scaled Quantum Mechanics Force Field (SQMFF) methodology, a comprehensive analysis was conducted to assign the vibrational spectra of three antimony (III) compounds, [1a-3a], that possess pyridine and pyrimidine ligands. The potential energy distribution (PED) was calculated and utilized to assign the IR spectra of the antimony (III) compounds. The theoretical frontier molecular orbital descriptors, the partial and total density of state distribution (TDOS, PDOS), molecular electronic potential surface map (MEP), nonlinear optical properties (NLO) of these complexes also were computed and investigated. The DFT/B3LYP/GEN (C, H, N, Cl: 6-31G(d,p) and Sb: LanL2DZ) level was utilized for all DFT calculations using the Gaussian 09W program. Furthermore, theoretical frontier molecular orbital descriptors, including electronegativity, chemical potential, softness, electrophilicity index, and electron affinity for six antimony (III) compounds were calculated ([1a/1b-3a/3b]). The results showed that, the ionization potential energy value of the [3a], which had the lowest experimental Leishmania activity, was also found to be the lowest among the others.