Engineering Chemistry, ISSN: 2813-6535, Vol. 13, pp 23-38

doi: 10.4028/p-9tPQ07

© 2026 The Author(s). Published by Trans Tech Publications Ltd, Switzerland.

Accepted:
2025-10-29

Theoretical and Experimental Study Using Hyperchem-8 and Gaussian Computer Program to Study the Stability, Binding Energies, and Electrical Characteristics of Triazole-Based Metal Complexes in the Gas Phase

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Jihan Hameed Abdulameer , Adnan I. Mohammed , Mahasin F. Alias and Muntahaa Abdullah REISHAAN

Department of Chemistry, College of Education for Pure Sciences, University of Kerbala, Iraq.

Department of Chemistry, College of Science, Kerbala University, Karbala, Iraq

Department of Chemistry, College of Science for Women, University of Baghdad, Iraq.

Department of Anesthesia, College Health and Medical Technology, University of Alkafeel Najaf, Iraq

Jihan.hameed@uokerbala.edu.iq, adnan.i@uokerbala.edu.iq,

mahasinfa_chem@csw.uobaghdad.edu.iq, muntaha.abd@alkafeel.edu.iq

Keywords: ligand-chelate complexes, Heat of formation, binding energy, and dipole moment, LUMO, HOMO.

Abstract

The study involves treating various metal complexes in "gas phase" with the prepared ligands (2,6-bis(((1-octyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine ( ), 2,6-bis(((1-decyl-1H-1,2,3-triazol-4-yl) methoxy) methyl) pyridine ( ) and 2,6-bis(((1-dodecyl-1H-1,2,3-triazol-4yl)methoxy) methyl) pyridine ( ). Two different types of programs, the Hyperchem- 8 and Gaussian programs, were used to study the theory. The heat of formation ( ), binding energy ( ), and dipole moment ( ) for free ligands and some metal complexes were calculated using semiexperimental and molecular mechanics in the Hyper-8 program using a variety of computational techniques including ZINDO/1, PM3, and AMBER methods at room temperature. The created complexes are discovered to be more stable than the free ligands. For proper location of the molecules, Hyperchem. -8 was used to determine the vibration frequencies for (FT-IR) and electronic transitions, as well as electrostatic potential, HOMO, and LUMO energy. The compatibility of the theoretical and experimental findings was highlighted. In order to calculate the geometry optimization, dipole moment ( ), total energy, electrostatic potential, LUMO, and HOMO, a Gaussian algorithm employing a semi-empirical (PM3) approach was utilized. "Vibration spectra of free ligands are calculated and noted that they agreed well with those values experimentally found" diagnosis with a higher level of capacity to effectively diagnose packages. Using a technique like ZINDO/S, the electronic transitions for the ligand were also computed.

1. Introduction

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In the past ten years, quantum computing has been extensively used to address a range of difficult mathematical problems connected to quantum physics, following significant commercial breakthroughs in the field [1]. The computer industry and its software have helped many researchers find atoms and compounds that were challenging or impossible to study. Many research projects employing ever-evolving computer software have been used to discover it [2]. The theoretical study that is the subject of our examination is one of the most significant investigations carried out today because it is totally based on theoretical concerns [3]. Because the investigation was carried out using a computer and an application, it might be regarded as a simulated experiment. This kind of research has demonstrated its value in precisely reproducing material properties, excluding a few mistakes [4,5]. Using two semi-experimental programs, Hyper-Chem and Gaussian computation of the prepared bonds with various metal complexes , our theoretical research will concentrate on investigating these compounds theoretically in the gas phase in order to: - Calculate the heat of
formation ( ), binding energy ( ), and dipole moment ( ) for each potential geometry and display the best stable conformation. The most active ligands are identified and their HOMO and LUMO positions are displayed using electron potential (Ep) calculations. Set the majority of the diagnostic ranges with certainty by computing the electronic transition and vibration frequencies of the associations and comparing the findings to the experimental transition and vibration frequencies[9,10].

2 Materials and Methods

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Theoretical treatment

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(2-1) Programs used Hyperchem and Gaussian in theoretical calculation:

(2-1-1) Types of calculation:

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In recent years, Hyperchem and Gaussian programs have been used in theoretical programs. These programs stand out for their simplicity and adaptability in use, as well as their use with both organic and inorganic compounds and a wide range of metals[11,12].

In this study, the heat of formation, the dipolar bond energy moment, the IR, UV, HOMO, and LUMO calculations for produced ligands, as well as all complexes prepared using the Hyperchem-8 program, were computed.

(2-2) Computational Methods:

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(2-2-1) Semi-Empirical:

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The heat of formation, binding energy, and dipole moment of metallic bonds and complexes were calculated using Zerner's INDO method (ZINDO/1), PM3, and (ZINDO/S), which is one of the 12 methods that make up the semi-experimental approach[13,14]. PM3 and (ZINDO/S) were used to determine the ligands' electrical and vibrational spectra.

(2-2-2) Molecular Mechanics:

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Many variables, such as the number of atoms, the functional form, and the atomic patterns, affect molecular mechanics. The complexes' formation heat, bond energy, and dipole moment were calculated using the Energy Building and Refinement Model (AMBER).

3 Results and Discussion

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Theoretical study:

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Using two programs, Hyperchem- 8 and Gaussian arithmetic, components of heat ( ), binding energy ( ), dipole moment ( ), vibrational and electronic transmission frequency spectroscopy, molecular orbital energy, and vacant high and low molecular orbitals were determined(EHOMOELUMO) [15].

(3-1) Theoretical energies and the dipole moment:

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The molecular dipole moment is the only empirical measure of the price density of the molecule. Using the PM3, ZINDO/1, and AMBER methodologies, the heat composition ( ), binding energy , and dipole moment of free bonds and their metal complexes were calculated [16,17]. As shown in Table 1, complexes are more stable than free bonds based on the results of using Hyperchem-8.

Table 1. Heat of formation, binding energy (Kcal.mol ) and dipole moment (in Debye) for all ligands and their metal complexes calculated with Hyperchem-8.

PM3 | ZINDO/1 | AMBER
Comp. | ΔH°f | ΔEb | μ | ΔH°f | ΔEb | μ | ΔH°f =ΔEb
L₁ | -11.8206 | -2302.901 | 8.201 | -10322.221 | -14636.943 | 5.23 | 42.8725
Mn-L₁ | -84.272 | -8704.092 | 13.78 | -16704.499 | -25324.319 | 5.938 | 156.312
Ni-L₁ | -169.638 | -8668.252 | 7.083 | -16866.126 | -25364.740 | 6.593 | 134.348
L₂ | -10.1635 | -9425.261 | 8.092 | -18494.2620 | -27909.360 | 10.19 | 46.1571
Mn-L₂ | 110722.631 | 101210.843 | 2.077 | 145897.817 | 136386.029 | 1.017 | 323.064
Rh-L₂ | 113548.637 | 103971.541 | 1.36 | 133647.951 | 124070.863 | 1.288 | 327.032
Pd-L₂ | 96926.87 | 87421.77 | 1.812 | 140706.71 | 131201.619 | 3.082 | 110.556
L₃ | -32.7872 | -10548.261 | 7.854 | -20666.3135 | -31181.787 | 10.5 | 47.2726
Mn-L₃ | 128884.701 | 118272.537 | 1.234 | 131947.329 | 121335.165 | 1.343 | 272.517
Rh-L₃ | 121533.701 | 110856.238 | 1.774 | 138398.914 | 127721.45 | 1.663 | 265.145
Pd-L₃ | -185.481 | -10790.955 | 2.758 | -21575.46 | -32180.93 | 6.304 | 108.453

As indicated in Table 2, the semi-empirical (PM3) method can be used to estimate the total energy and dipole moment for all produced ligands using the program (Gaussian Gauss View Currently Available Versions 5.0.9).

Table 2. Total energy in ( ) and dipole moment in (Debye) calculated using the Gaussian software for all produced ligands.

Comp. | Total energy | μ
L₁ | 0.12753359 | 6.3793
L₂ | 0.12399370 | 8.6931
L₃ | 0.09678410 | 8.1826

(3-2) Theoretical Computation of Ligands Vibration Frequencies:

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As indicated in Tables 3 to 5 for both programs, the PM3 technique was employed to predict the vibration spectra of the generated compounds because it is in perfect agreement with the experimental data [18]. One can use theoretical spectra created by quasi-empirical calculations to comprehend the observed peaks in the spectrum. We identified the vibrational peaks of free connections. Figures 1 to 3 show data from Hyperchem- 8 and Gaussian, while Figures 4 to 6 show the results. The theoretical frequencies of the produced races deviate from the experimental findings in some ways. Errors or variances in frequency calculations can be caused by a number of variables, including the coupling of the vibration mode, the mismatch of large-amplitude vibration modes, and the approximation in which each normal mode of vibration interacts with the IR beam.

Table 3. Using the Gaussian and Hyper Chem-8 programs, the vibrational frequencies of were calculated.

Symb.
ν (C-H)Py.
ν (C-H) tri.
ν (N=N)
ν (C=N)Py.
ν (C-N)tri.
ν (C-O-C)

*Exp.
3091.99
3136.36
1595.18
1508.38
1220.98
1122.61

Hyper.
3077.31
(0.48)
3100.55
(1.15)
1716.45
(-7.06)
1575.37
(-4.25)
1262.05
(-3.25)
1148.69
(-2.27)

Gass.
3078.50
(0.44)
3119.24
(0.55)
1715.35
(-7.01)
1578.69
(-4.50)
1272.06
(-4.02)
1136.04
(-1.18)

Table 4. Using the Gaussian and Hyper Chem-8 programs, the vibrational frequencies of were calculated.

Symb.
ν (C-H)Py.
ν (C-H) tri.
ν (N=N)
ν (C=N)Py.
ν (C-N)tri.
ν (C-O-C)

*Exp.
3091.99
3138.29
1593.25
1503.25
1220.98
1122.61

Hyper.
3076.99
(0.49)
3122.36
(0.51)
1602.14
(-0.55)
1577.45
(-4.93)
1262.06
(-3.25)
1167.95
(-3.88)

Gass.
3078.52
(044)
3119.36
(0.61)
1604.66
(-0.71)
1578.69
(-4.78)
1274.01
(-4.16)
1134.76
(-1.07)

Table 5. Using the Gaussian and Hyper Chem-8 programs, the vibrational frequencies of were calculated.

Symb.
ν (C-H)Py.
ν (C-H) tri.
ν (N=N)
ν (C=N)Py.
ν (C-N)tri.
ν (C-O-C)

*Exp.
3093.29
3138.29
1595.18
1505.04
1220.98
1122.61

Hyper.
3060.67
(1.06)
3124.23
(0.45)
1600.67
(-0.34)
1562.15
(-3.65)
1259.00
(-3.01)
1130.63
(-0.71)

Gass.
3058.85
(1.13)
3119.39
(0.61)
1604.68
(-0.59)
1578.69
(-4.66)
1274.78
(-4.22)
1135.11
(-1.10)

Where:
*: Experimental frequency.
: Theoretical frequency.
( ): Error % due to main different in the experimental measurements and theoretical treatment of vibrational spectrum.

Fig. 1. HyperChem-8 and Gaussian programs were used to calculate the vibrational frequencies of ( ).

Fig. 1. HyperChem-8 and Gaussian programs were used to calculate the vibrational frequencies of ( ).

Fig. 2. HyperChem- 8 and Gaussian programs were used to calculate the vibrational frequencies of .

Fig. 2. HyperChem- 8 and Gaussian programs were used to calculate the vibrational frequencies of .

Fig. 3. HyperChem- 8 and Gaussian programs were used to calculate the vibrational frequencies of ( )

Fig. 3. HyperChem- 8 and Gaussian programs were used to calculate the vibrational frequencies of ( )

Fig.4. The vibrational frequencies of the molecules were calculated using the HyperChem-8 and Gaussian programs

Fig.4. The vibrational frequencies of the molecules were calculated using the HyperChem-8 and Gaussian programs

Fig. 5. The vibrational frequencies of the molecules were calculated using the HyperChem- 8 and Gaussian programs (L2)

Fig. 5. The vibrational frequencies of the molecules were calculated using the HyperChem- 8 and Gaussian programs (L2)

Fig. 6. The vibrational frequencies of the molecules were calculated using the HyperChem-8 and Gaussian programs (L3)

Fig. 6. The vibrational frequencies of the molecules were calculated using the HyperChem-8 and Gaussian programs (L3)

(3-2) Theoretical Computation of Ligands Electronic Spectra:

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The PM3 and ZINDO/S methods are used to compute the theoretical UV spectra of ligands. It revealed some differences from the experimental results, although these differences were typical for theoretical computations [19,20]. As shown in Figure 7, the kind of orbital and subsequent type of transition are determined by the serial number of atoms, which is drawn into the ligand structure. According to the ZINDOS method, the theoretical UV spectrum of the ligand exhibits three bands at , and 257.70 nm due of the transitions or or and or or or or or or and ) transitions respectively, as shown in Figure 8. for aromatic ring. While the experimental spectrum showed three bands at 237,256 and 265 nm assigned to and ,
respectively. Three peaks at , and 257.00 nm appeared in the theoretical spectra of by ZINDO's approach, respectively. due of the transitions or or and or or or or or or and ) transitions respectively, as shown in Figure 9. while the experimental spectrum is about 254,264 , and 371 nm assigned to and respectively. Three bands were present in the theoretical spectrum of the ligand L3 at 223.97, 243.65 , and 255.71 nm , respectively assigned to or or and or or or or or or and transitions respectively, Figure 10. while the experimental spectrum is about 219, 239, 265 nm attributed to and . According to Table 6, all of the aforementioned data were acquired using the Hyperchem - 8 application, while Gaussian program can provide ( max) using a single point energy (SP) with ZINDO method for ligands by using type frequency (freq.) as represented in Table 7. For the three ligands respectively.

Table 6. Calculation of UV spectra of ligands using PM3 and ZINDOS and experimentation using the HyperChem-8 program

Symb.
Assignment Transition
Experimental (nm)
Theoretical ZINDO\S(nm)

L₁
n→π*
π→π*
265
256
237
257.70
243.72
223.25

L₂
n→π*
π→π*
371
264
254
257.00
249.02
223.59

L₃
n→π*
π→π*
265
239
219
255.71
243.65
223.97

Table 7. Comparison of experimental and theoretical electronic transitions for ligands using the Gaussian program and ZINDO calculations.

Symb.
Assignment transition
Experimental
(nm)
Theoretical ZINDO (nm)

L₁
n→ π*
π → π*
265
256
237
318
316

L₂
n→ π*
π → π*
371
264
254
327
315
318

L₃
n→ π*
π → π*
265
239
219
330
318
309

Fig.7. The number of atoms of ligands and using Hyper-chem8 program

Fig.7. The number of atoms of ligands and using Hyper-chem8 program

Fig. 8. Theoretical uv -spectrum of ligand using HyperChem- 8 and Gaussian programs.

Fig. 8. Theoretical uv -spectrum of ligand using HyperChem- 8 and Gaussian programs.

Fig. 9. Theoretical UV -spectrum of ligand ( ) using HyperChem- 8 and Gaussian programs.

Fig. 9. Theoretical UV -spectrum of ligand ( ) using HyperChem- 8 and Gaussian programs.

Fig.10. Theoretical UV -spectrum of ligand ( ) using HyperChem- 8 and Gaussian programs.

Fig.10. Theoretical UV -spectrum of ligand ( ) using HyperChem- 8 and Gaussian programs.

(3-3) Frontier Molecular Orbitals and Electrostatic Potential (E.P):

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Further examination of the reactive bond locations to determine the electronic dispersion and electrostatic potential concentration based on the electronic density. The interaction of the energy molecule system with the positive point charge was characterized by the electronic potential (EP). To identify the reactive portions of the molecule, the E.P. of the connections is depicted in two and three dimensions [21].
Moreover, the stereochemistry and kinetics of various processes involving soft electrical materials and nucleophiles can be explained by boundary orbital characteristics (HOMO & LUMO). In many reactions, HOMO-LUMO interference serves as a control. The HOMO and LUMO values were displayed as a 3D counter to learn more about these compounds [22]. As seen in Figures 11 and 12, the LUMO of transition metal ions prefers to interact with the HOMO of the donor atoms in the bonds that are created. utilizing the Gaussian program and Hyperchem-8.

Fig. 11. HOMO& LUMO and Electrostatic potential as 2& 3D counters for Ligands by Hyperchem-8 program

Fig. 11. HOMO& LUMO and Electrostatic potential as 2& 3D counters for Ligands by Hyperchem-8 program

Fig. 12. HOMO& LUMO and Electrostatic potential as 2& 3D counters for Ligands by Gaussian program.

Fig. 12. HOMO& LUMO and Electrostatic potential as 2& 3D counters for Ligands by Gaussian program.

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