QUANTUM CHEMICAL STUDIES OF METHYL N-(6-PROPYLSULFANYL-1H BENZIMIDAZOL-2-YL)CARBAMATE

Аннотация

This study presents a quantum chemical analysis of methyl n-(6-propylsulfanyl-1h- benzimidazol-2-yl)carbamate, focusing on its electronic structure, stability, and potential as a coordinating ligand. Using the Restricted Hartree-Fock (RHF) method with the STO-3G basis set, key parameters such as HOMO-LUMO energy levels, electron density, charge distribution, dipole moment, and total energy were determined. Keywords: Quantum chemical calculations, benzimidazole derivatives, HOMO-LUMO gap, electronic properties, coordination compounds, dipole moment, charge distribution, molecular orbitals, computational chemistry, ligand interactions. Quantum chemical studies of benzimidazole derivatives have become increasingly relevant due to their significant implications in medicinal chemistry and materials science. These studies typically involve computational methods to predict the electronic structure, stability, and reactivity of these compounds, which can be correlated with their biological activities and potential applications [1.985 p.]. This report provides an analysis of a quantum chemical optimization calculation for methyl n- (6-propylsulfanyl-1h-benzimidazol-2-yl)carbamate, performed using Gaussian software. The calculation employs the Restricted Hartree-Fock (RHF) method with the STO-3G basis set for structural optimization. The key computational details, atomic composition, and relevant electronic properties are outlined in this report. The above method was also used to calculate electron density potentials (ESP) of ligands and complexes. Several chemical parameters, such as (E ), (E ), HOMO LUMO energy gap between HOMO and LUMO orbitals (E = E − E ), electronic charges of gap HOMO LUMO each atom, electronic density of molecule and dipole moment (µ) were calculated. Figure 1. Graphic representation of charge distribution and total electron density in atoms of n-(6-propylsulfanyl-1h-benzimidazol-2-yl)carbamate In figure 1 shown the charge distribution of each atom and total electron density of the compound calculated using the ab initio method. As you can see in the figure, the number one and number three nitrogen atoms in benzimidazole ring have the high negative charges. Their values are -0.345 and -0.306 respectively. There is also the carbonyl’s oxygen atom in carbamate group has 209 RESPUBLIKA ILMIY-AMALIY KONFERENSIYASI 7-8-MAY 2025-YIL the highest negative charge within carbamate group, it’s value is -0.305. Total electron density image also supports this calculation by showing thick orange-red patterns around these atoms which shows the abundance of electron pairs. This property allows the compound to form coordination compounds with transition metals. Understanding the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) is crucial for analyzing the electronic properties of ligands and coordination compounds. The HOMO represents the highest energy level of electrons that are occupied in a molecule. It is primarily involved in electron donation during chemical reactions. The LUMO is the lowest energy level that can accept electrons. It plays a critical role in electron acceptance processes [2.2456 p.] (Shown in the Figure 2.). Figure-2 displays a graphical depiction of these values for the n-(6-propylsulfanyl-1h- benzimidazol-2-yl)carbamate. The color red-brown indicates high electron density in the molecular orbital, whereas green indicates low electron density. Figure 2. Graphical representation of the calculated HOMO and LUMO orbitals of n-(6- propylsulfanyl-1h-benzimidazol-2-yl)carbamate The energy gap between these two orbitals is known as the HOMO-LUMO gap. It refers to the energy difference between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO). This gap plays a significant role in determining the electronic, optical, and chemical properties of molecules. A larger HOMO-LUMO gap generally indicates greater stability and lower reactivity of a compound. Conversely, a smaller gap suggests higher reactivity and lower stability [3.4 p.]. Table 1 below presents the calculated values of the HOMO and LUMO orbitals for the compound as well as total energy and dipole moments, utilising quantum chemical calculation methods. Compound Total Dipole E E E HOMO LUMO gap energy moment (eV) (eV) (a.u.) (µ/debye) n-(6-propylsulfanyl-1h- -1159.726 2.5922 -0.7682 0.6870 1.4552 benzimidazol-2- yl)carbamate Table 1. The HOMO and LUMO energies of the compound and the difference between them, as well as the total energy and dipole moment, are given The quantum chemical calculations provide essential insights into n-(6-propylsulfanyl-1h- benzimidazol-2-yl)carbamate’s potential as a ligand in complex formation. The total energy of - 1159.726 a.u. reflects the stability of the molecule in its isolated state, which is crucial when considering its behavior in coordination chemistry. The dipole moment of 2.5922 Debye indicates a degree of p