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QUANTUM CHEMICAL STUDIES OF METHYL N-(6-PROPYLSULFANYL-1H-
BENZIMIDAZOL-2-YL)CARBAMATE
Shonazar Safayev
Doctoral student of Khorezm mamun academy, Uzbekistan, Khiva
e-mail:
shonazarsafaev@gmail.com
Shahnoza Kadirova
Doctor of chemical sciences, head of the chemistry department, National university of Uzbekistan,
Uzbekistan, Tashkent
Zubayda Abdullayeva
Doctor of philosophy in chemistry, lecturer, Urgench “Ranch” university, Uzbekistan, Urgench
Abstract:
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
HOMO
), (E
LUMO
),
energy gap between HOMO and LUMO orbitals (E
gap
= E
HOMO
− E
LUMO
), electronic charges of
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
RESPUBLIKA ILMIY-AMALIY KONFERENSIYASI 7-8-MAY 2025-YIL
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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
energy
(a.u.)
Dipole
moment
(µ/debye)
E
HOMO
(eV)
E
LUMO
(eV)
E
gap
n-(6-propylsulfanyl-1h-
benzimidazol-2-
yl)carbamate
-1159.726
2.5922
-0.7682
0.6870
1.4552
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 polarity that may influence its interaction with metal ions, affecting solubility and
coordination tendencies. The HOMO energy of -0.7682 eV and LUMO energy of 0.6870 eV result
in an energy gap of 1.4552 eV, suggesting a capacity for electronic transitions that could facilitate
charge transfer interactions with metal centers. These quantum chemical parameters highlight n-(6-
propylsulfanyl-1h-benzimidazol-2-yl)carbamate’s electronic structure, reinforcing its potential as a
coordinating ligand in metal complex formation.
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Conclusion
The quantum chemical analysis of methyl n-(6-propylsulfanyl-1h-benzimidazol-2-
yl)carbamate provides valuable insights into its electronic properties, stability, and potential as a
coordinating ligand. The calculated HOMO-LUMO gap of 1.4552 eV suggests moderate reactivity,
while the dipole moment of 2.5922 Debye indicates polarity that may influence metal-binding
interactions. Charge distribution analysis highlights key donor sites within the molecule, reinforcing
its potential for coordination with transition metals.
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‐
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2. Gould, Tim et al. “Single Excitation Energies Obtained from the Ensemble "HOMO-
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