Synthesis, spectroscopic characterization, crystal structure and computational studies of two new N-aroyl-N′-(2,4,6-tribromophenyl)thioureas European Journal of Chemistry 15 (2) (2024) 155-165 European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2024 The Authors – Atlanta Publishing House LLC – Printed in the USA. This work is published and licensed by Atlanta Publishing House LLC – CC BY NC – Some Rights Reserved. https://dx.doi.org/10.5155/eurjchem.15.2.155-165.2551 European Journal of Chemistry View Journal Online View Article Online Synthesis, spectroscopic characterization, crystal structure and computational studies of two new N-aroyl-N′-(2,4,6-tribromophenyl)thioureas Nahide Burcu Arslan 1 and Fatma Aydin 2,* 1 Department of Computer Education and Instructional Technology, Faculty of Education, Giresun University, 28200, Giresun, Turkey 2 Department of Chemistry, Faculty of Science, Canakkale Onsekiz Mart University, 17100, Canakkale, Turkey * Corresponding author at: Department of Chemistry, Faculty of Science, Canakkale Onsekiz Mart University, 17100, Canakkale, Turkey. e-mail: faydin@comu.edu.tr (F. Aydin). 10.5155/eurjchem.15.2.155-165.2551 Received: 15 March 2024 Received in revised form: 16 April 2024 Accepted: 4 May 2024 Published online: 30 June 2024 Printed: 30 June 2024 Two new compounds, N-benzoyl-N'-tribromophenylthiourea (I) and 4-nitrobenzoyl-N'- tribromophenylthiourea (II), were synthesized and characterized by 1H NMR, 13C NMR, IR, and X-ray single crystal diffraction techniques. The molecular geometry of compounds I and II in the ground state has been calculated by using the density functional theory (DFT) method with the B3LYP/6-311G(d,p) basis set and compared with the experimental data. The calculated results show that the optimized geometry can reproduce well the crystal structural parameters. A detailed vibrational spectral analysis has been carried out, and assignments of the observed fundamental bands have been proposed on the basis of peak positions. The scaled theoretical frequencies show very good agreement with the experimental values. Frontier molecular orbitals energies (HOMO and LUMO), energy gap, and global chemical reactivity parameters such as ionization potential, electron affinity, chemical hardness, and chemical softness have been calculated, and the sites of electrophilic and nucleophilic regions where the molecular interactions likely to happen are identified. The molecular electrostatic potential and thermodynamic properties of the title compounds were investigated by theoretical calculations. Single crystal structure HOMO and LUMO analysis X-ray structure determination Electronic structure properties Molecular electrostatic potential N-Benzoyl-N'-tribromophenylthiourea Cite this: Eur. J. Chem. 2024, 15(2), 155-165 Journal website: www.eurjchem.com 1. Introduction The derivatives of aroyl/acylthiourea due to the hetero- atom content are known for their several biological activities, including antifungal, antibacterial, antiviral, insecticidal, herbicidal, etc. effects [1-5]. They are an important class of organic compounds having O-, N- and S-atoms. The amide, carbonyl, thioamide, and thiocarbonyl groups of the C(O)-NH- C(S)-N core fragment that can participate in the tautomer are in the same molecule [6,7] leading to physicochemical and biological properties suitable for application in the field of coordination chemistry [8-10]. In addition, their derivatives consist of heteroatoms such as nitrogen and sulfur, which are nucleophilic centers, allowing the formation of intermolecular and intramolecular hydrogen bonds in the crystal structure [11-13]. Steric hindrance slows down chemical reactions due to steric mass [14]. Generally, steric hindrance gains importance in intermolecular reactions, but it also determines inter- molecular interactions in the crystal lattice structure [15]. In addition, it is often used to control selectivity, such as slowing down undesired side reactions [16,17]. In the present work, two novel compounds, N-benzoyl-N'- (2,4,6-tribromophenyl)thiourea (I) and N-4-nitrobenzoyl-N'- (2,4,6-tribromophenyl) thiourea (II) were synthesized in high yield, via aroyl isocyanates and 2,4,6-tribromoaniline (Scheme 1). The structural characterization of compounds I and II has been confirmed using FT-IR and NMR spectroscopy techniques and a single crystal X-ray diffraction method. The unit cells of the crystal were compared with similar molecules in terms of steric hindrance. The geometrical parameters of the title compounds in the ground state have been calculated using the density functional theory (DFT) method with the B3LYP/6- 311G (d,p) basis set and the experimental data were compared. After optimization of molecular geometry, the molecular electrostatic potential (MEP) map, the highest occupied mole- cular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) analyzes, and thermodynamic properties were calculated by using density functional theory (DFT) at the B3LYP/6-311G(d,p) level. 2. Experimental 2.1. Material and measurements All reagents (except 2,4,6-tribromoaniline) and solvents used in the synthesis were commercially purchased from Sigma-Aldrich, Merck Chemical. ABSTRACT RESEARCH ARTICLE KEYWORDS https://dx.doi.org/10.5155/eurjchem.15.2.155-165.2551 https://www.eurjchem.com/ https://dx.doi.org/10.5155/eurjchem.15.2.155-165.2551 mailto:faydin@comu.edu.tr http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.15.2.155-165.2551&domain=pdf&date_stamp=2024-06-30 156 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Scheme 1. Synthesis pathway of compounds I and II. Figure 1. A view of compound I with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level, and H atoms are shown as small spheres of arbitrary radii. Figure 2. A view of compound II, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level, and H atoms are shown as small spheres of arbitrary radii. The melting points were determined in open capillary tubes using an IA 9100 Electrothermal apparatus. Reactions were monitored by thin layer chromatography (TLC) on silica gel 60F254 plates (Merck). The infrared (FT-IR) spectrums were recorded on the PerkinElmer Spectrum 100 FT-IR spectro- meter in a spectral range of 4000-650 cm-1. The 1H NMR and 13C NMR spectra were recorded on a JEOL ECX-400 FT-NMR spectrometer operating at 400 and 100 MHz, respectively, using DMSO-d6 as a solvent. Crystal structure analyzes of the title compounds were carried out using a Bruker APEX-II CCD X-ray diffractometer (MoKα radiation, λ = 0.71073 Å). 2.2. Synthesis and characterization 2,4,6-Tribromoaniline was synthesized in the literature [15]. A solution of aroyl chloride (benzoyl- and 4-nitrobenzoyl, 2.32 mL and 3.70 g, 20 mmol, respectively) in dry acetone (20 mL) was added dropwise to a round bottom three-neck flask containing potassium thiocyanate solution in acetone (10 mL) (1.94 g, 20 mmol). The mixtures were refluxed for approxi- mately 1 hour and then cooled to room temperature. Then, a solution of 2,4,6-tribromoaniline (0.652 g, 20 mmol) in dry acetone (20 mL) was added dropwise over 0.5 h, without filtration obtained white benzoyl isothiocyanate and pale yellow 4-nitrobenzoyl isothiocyanate, and the mixture was stirred for 2 and 3 h, respectively. The resulting mixture was pushed into 100 mL of water and filtered, washed with hot water to remove inorganic salts, and dried under vacuum. Subsequently, the raw product was chromatographed on silica gel using ethyl acetate: hexane (4:1, v:v) as an eluent to separate the product. After evaporation of the solvent, the fairly pure, colorless (I) and pale-yellow (II) products were crystallized, respectively (Scheme 1). N-Benzoyl-N׳-(2,4,6-tribromophenyl)thiourea (I): Color: Colorless. Yield: 0.857 g, 87%. M.p.: 207-208 °C. 1H NMR (400 MHz, DMSO-d6, δ, ppm): 12,08 (s, 1H, NH), 11.94 (s, 1H, NH), 8.04 (s, 2H, Ar(Br)3-H), 8.02 (d, J = 7.7 Hz, 2H, Ar-H), 7.69 (t, 2H, Ar-H), 7.56 (s, 1H, Ar-H). 13C NMR (100 MHz, DMSO-d6, δ, ppm): 180.75 (C=S), 168.04 (C=O), 136.94, 131.71, 128.50, 121.40 (Ar(Br)3-C), 134.23, 133.34, 128.76, 125.08 (Ph-C). FT-IR (ATR, ν, cm-1): 3255 (N-H), 3112 (N-H), 3099, 3074, 3003 (Car_H), 1670 (C=O), 1603 (C=C), 1506 (N-CS, thioureido), 1343 (N-CO), 1262 cm-1 (CS-N), 861 (C=S, stretching), 778, 739, 701 (C-Br). Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 157 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Table 1. Crystal data and structure refinement parameters for compounds I and II. Parameters Compound I Compound II Empirical formula C14H9Br3N2OS C14H8Br3N3O3S Formula weight 493.02 538.02 Temperature (K) 293 293 Crystal system Monoclinic Orthorhombic Space group P21/n Pbca a, (AÅ ) 8.0437(13) 16.5477(12) b, (AÅ ) 37.021(6) 7.4257(6) c, (AÅ ) 10.7842(15) 28.378(2) Volume (Å3) 3210.9(8) 3487.1(5) Z 8 8 ρcalc (g/cm3) 2.040 2.050 α , β , γ (°) 90, 90.936 (5), 90 90, 90, 90 μ (mm-1) 7.666 7.077 F(000) 528.0 528.0 Crystal size (mm3) 0.12×0.09×0.07 0.09×0.07×0.03 Colour / Shape Colourless / Prism Pale yellow / Block Radiation MoKα (λ = 0.71073) MoKα (λ = 0.71073) 2Θ range for data collection (°) 2.9 ≤ θ ≤ 26 2.9 ≤ θ ≤ 25.1 Reflections collected 36579 27641 Independent reflections 6301 3061 Data/restraints/parameters 6301/0/380 3061/0/181 N-4-Nitro-benzoyl-N׳-(2,4,6-tribromophenyl)thiourea (II): Color: Pale yellow. Yield: 0.775 g, 72 %. M.p.: 221-222 °C. 1H NMR (400 MHz, DMSO-d6, δ, ppm): 12.25 (s, 1H, NH), 11.86 (s, 1H, NH), 8.31 (d, 2H, Ar(NO2)-H), 8.17 (d, J = 7.7 Hz, 2H, Ar(NO2)-H), 7.99 (s, 2H, Ar(Br)3-H). 13C NMR (100 MHz, DMSO- d6, δ, ppm): 180.91 (C=S), 167.09 (C=O), 138.04, 134.78, 125.56, 122.04 (Ar(Br)3-C), 150.46, 137.42, 130.91, 123.95 (Ar(NO2)-C. FT-IR (ATR, ν, cm-1): 3413 (N-H), 3284 (N-H), 3180, 3095, 3073 (Caromatic _H), 1728 (C=O), 1607 (C=C), 1539 (N-CS, thioureido), 1381 (-N-CO), 1276 (CS-N), 1346 (ON=O), 858 (C=S stretching) and 729, 705, 700 (C-Br). 2.3. X-ray data collection and structure refinement The single-crystal X-ray data were collected on a Bruker APEX-II. All diffraction measurements were performed at room temperature (296 K) using graphite monochromated MoKα radiation (λ = 0.71073 Å). Unit cell parameters were deter- mined from the least-squares refinement of setting angles with θ for compounds I and II in the range of 2.9 ≤ θ ≤ 26 and 2.9 ≤ θ ≤ 25.1, respectively. The structures were solved by direct methods using SHELXS-97 [18] implemented in the WinGX [19] program suite. The refinement was carried out using the full- matrix least squares method on the positional and anisotropic temperature parameters of the nonhydrogen atoms, or equivalently corresponding to 380 crystallographic parameters for compound I and 181 crystallographic parameters for compound II, using SHELXL-97 [18]. All H atoms of compound I and compound II were geometrically positioned and treated using a riding model, fixing the bond lengths at 0.86 and 0.93 Å for the NH and CH atoms, respectively. Details of the data collection conditions and refinement process parameters for the two compounds are given in Table 1. Bond lengths and angles for compounds I and II are given in Tables 2 and 3, respectively. Atomic numbering schemes with displacement ellipsoids of crystal structures drawn with ORTEP III [19] were depicted at the 30% probability level for clarity (Figures 1 and 2). 2.4. Computational procedures The ground-state geometry of title compounds I and II that are taken from the crystal structure was optimized using the standard density functional theory (DFT) [20] level of B3LYP [21] with a basis set 6-311G(d,p) [22] using the Gaussian 09 program [23]. After optimization, quantum chemical calcula- tions were made and a MEP surface map [24] was obtained. Thus, from the results of the MEP map, the chemical reactivity of the compound could be easily estimated. Additionally, the HOMO-LUMO gaps and the FT-IR spectrum were calculated on the same basis set. The calculated vibrational frequencies of the optimized molecular structure were then scaled by 0.962 [25] for DFT. The vibrational band assignments were performed using the Gauss-View molecular visualization program [26]. 3. Results and discussion 3.1. Description of the crystal structure As shown in Figures 1 and 2, the crystals of compounds I and II crystallize in the monoclinic space group P21/n and the orthorhombic space group Pbca, respectively, with Z = 8. Both molecules have thiourea, 2,4,6-tribromophenyl and phenyl groups in common. The torsion angles between the 2,4,6- tribromophenyl and thiourea groups in the title compounds are 96.2 and 84.0°, respectively. In compound I, the molecular packing contains three different types of hydrogen bonds between C-H···Br, N-H···O, and N-H···S atoms, which are tabulated in Table 4. The N atom of the thiourea group acts as a donor atom to the benzoyl oxygen atom with the donor acceptor distance 3.273 Å and symmetry code (x, +y, +z-1). The other N atom of the same thiourea group also acts as a donor to the thiourea group S atom with the donor acceptor distance 3.353 Å and the symmetry code (x, +y, +z+1). The combination of these hydrogen bonds generates an R22(10) ring running parallel to [001], Figure 3. Similarly to compound I, compound II has a N-H···S type hydrogen bonding with donor acceptor distance 3.616 Å and symmetry code (-x+1, -y+2, -z+1). This bonding generates the R11(8) ring running parallel to [100]. Furthermore, there is an intramolecular hydrogen bond between the thiourea N atom and the benzoyl O atom, as seen in Table 4 and Figure 4. 3.2. Spectral analysis 3.2.1. Vibrational spectra The analysis of the experimental spectra of compounds I and II was supported by theoretical calculations using the B3LYP/6-311G(d,p) level of approximation (Figures 5 and 6). In addition, some vibration modes expected for compounds I and II of the title are presented in Table 5. The N-H stretching vibrations generally appear in 3300-3500 cm-1 [27,28]. In the IR spectrum, the stretching vibrations of the amide group observed at 3255 and 3413 cm-1 are assigned to the NH stretching mode of compounds I and II, respectively [29]. 158 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Table 2. Bond lengths and angles for compound I. Atom Atom Length (Å) Atom Atom Length (Å) C1 C2 1.392(18) C15 C16 1.309(19) C1 C6 1.409(19) C15 C20 1.42(2) C1 Br1 1.859(13) C15 Br4 1.889(15) C2 C3 1.37(2) C16 C17 1.38(2) C3 C4 1.423(19) C17 C18 1.36(2) C3 Br2 1.887(14) C17 Br5 1.882(14) C4 C5 1.418(17) C18 C19 1.416(18) C5 C6 1.34(2) C19 C20 1.38(2) C5 Br3 1.854(14) C19 Br6 1.900(14) C6 N1 1.421(17) C20 N3 1.448(16) C7 N1 1.336(19) C21 N3 1.309(18) C7 N2 1.414(17) C21 N4 1.430(16) C7 S1 1.643(16) C21 S2 1.643(15) C8 C9 1.478(19) C22 C23 1.505(19) C8 N2 1.367(19) C22 N4 1.341(19) C8 O1 1.219(18) C22 O2 1.222(18) C9 C10 1.41(2) C23 C24 1.40(2) C9 C14 1.35(2) C23 C28 1.36(2) C10 C11 1.42(2) C24 C25 1.40(2) C11 C12 1.42(3) C25 C26 1.37(3) C12 C13 1.22(3) C26 C27 1.32(3) C13 C14 1.42(3) C27 C28 1.39(2) Atom Atom Atom Angle (°) Atom Atom Atom Angle (°) C2 C1 C6 119.4(13) C20 C15 Br4 117.6(10) C2 C1 Br1 118.3(11) C15 C16 C17 121.7(15) C6 C1 Br1 122.2(10) C16 C17 Br5 120.6(12) C3 C2 C1 119.7(13) C18 C17 C16 119.9(13) C2 C3 C4 121.2(13) C18 C17 Br5 119.5(11) C2 C3 Br2 121.0(11) C17 C18 C19 118.7(14) C4 C3 Br2 117.8(10) C18 C19 Br6 117.9(11) C5 C4 C3 117.8(12) C20 C19 C18 121.3(14) C4 C5 Br3 116.8(10) C20 C19 Br6 120.8(10) C6 C5 C4 120.4(13) C15 C20 N3 123.5(13) C6 C5 Br3 122.8(10) C19 C20 C15 116.5(12) C1 C6 N1 119.1(13) C19 C20 N3 119.9(14) C5 C6 C1 121.5(12) N3 C21 N4 113.1(12) C5 C6 N1 119.3(13) N3 C21 S2 127.8(10) N1 C7 N2 115.0(13) N4 C21 S2 119.0(11) N1 C7 S1 125.2(11) N4 C22 C23 116.8(14) N2 C7 S1 119.8(12) O2 C22 C23 120.5(14) N2 C8 C9 115.7(15) O2 C22 N4 122.7(13) O1 C8 C9 122.6(14) C24 C23 C22 121.7(14) O1 C8 N2 121.6(13) C28 C23 C22 119.5(15) C10 C9 C8 121.4(14) C28 C23 C24 118.2(14) C14 C9 C8 118.5(16) C25 C24 C23 118.7(18) C14 C9 C10 119.5(15) C26 C25 C24 119.5(19) C9 C10 C11 117.8(18) C27 C26 C25 121.9(17) C10 C11 C12 118(2) C26 C27 C28 119.5(19) C13 C12 C11 122(2) C23 C28 C27 121.7(19) C12 C13 C14 122(2) C7 N1 C6 123.0(12) C9 C14 C13 120(2) C8 N2 C7 129.5(13) C16 C15 C20 122.0(14) C21 N3 C20 122.2(12) C16 C15 Br4 120.3(13) C22 N4 C21 129.4(13) Table 3. Bond lengths and angles for compound II. Atom Atom Length (Å) Atom Atom Length (Å) C6 C1 1.40(3) C2 C3 1.36(3) C6 C5 1.40(3) C3 C4 1.38(3) C6 C7 1.46(3) C3 N1 1.41(3) C13 C14 1.38(3) C5 C4 1.35(3) C13 C12 1.38(3) C7 N2 1.38(2) C8 N3 1.33(3) C7 O31 1.22(2) C8 N2 1.37(3) C7 O3 1.22(2) C8 S1 1.66(2) C10 C9 1.39(3) C11 C12 1.37(3) C10 Br1 1.89(2) C11 C10 1.38(3) C9 N3 1.41(2) C14 C9 1.38(3) N1 O2 1.22(3) C14 Br3 1.90(2) N1 O1 1.19(2) C12 Br2 1.91(2) O3 O31 0.00(5) C2 C1 1.40(3) Atom Atom Atom Angle (°) Atom Atom Atom Angle (°) C1 C6 C5 117.9(19) C5 C4 C3 120(2) C1 C6 C7 117.1(18) N2 C7 C6 118.4(17) C5 C6 C7 125.0(17) O31 C7 C6 119.8(18) C14 C13 C12 116(2) O3 C7 C6 119.8(18) N3 C8 N2 115.4(19) O31 C7 N2 121.8(18) N3 C8 S1 123.7(17) O3 C7 N2 121.8(18) N2 C8 S1 120.9(18) O31 C7 O3 0(2) C12 C11 C10 118(2) C11 C10 C9 122(2) C13 C14 C9 124.3(19) C11 C10 Br1 120.0(17) C13 C14 Br3 115.9(17) C9 C10 Br1 118.3(15) Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 159 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Table 3. (Continued). Atom Atom Atom Angle (°) Atom Atom Atom Angle (°) C9 C14 Br3 119.8(15) C14 C9 C10 116.5(18) C13 C12 Br2 120.0(16) C14 C9 N3 119.6(17) C11 C12 C13 122.7(19) C10 C9 N3 123.6(17) C11 C12 Br2 117.3(16) O2 N1 C3 120(2) C3 C2 C1 120(2) O1 N1 C3 122(2) C6 C1 C2 120(2) O1 N1 O2 118.8(19) C2 C3 C4 120.5(19) C8 N3 C9 123.8(17) C2 C3 N1 118.0(19) C8 N2 C7 127.7(18) C4 C3 N1 121(2) O31 O3 C7 0(10) C4 C5 C6 121(2) 1 Symmetry code: +x, +y, +z. Table 4. Hydrogen bonds for compound I and II. Compound D H A d(D-H) (Å) d(H-A) (Å) d(D-A) (Å) D-H-A (°) Symmetry I C4 H4 Br5 0.93 2.91 3.827(13) 168.6 2-x, 1-y, 1-z C16 H16 Br2 0.93 3.02 3.937(16) 167.4 1-x ,1-y, 1-z N2 H22 O2 0.86 2.43 3.273(17) 165.9 +x, +y, -1+z N3 H33 S1 0.86 2.76 3.353(13) 127.2 +x, +y, 1+z II N3 H3 O3 0.86 1.88 2.57(2) 137.0 x, +y, +z N2 H2A S1 0.86 2.77 3.616(17) 167.7 1-x, 2-y, 1-z Table 5. Experimental, calculated, and tentative of some relevant vibrational modes (cm-1) of compounds I and II. Compound I Compound II Assignment * Experimental Calculated Experimental Calculated 3255 3617 3413 3674 ν(N1-H) 3112 3515 3284 3339 ν(N2-H) 3099 3261 3180 3172 ν(C-H)Ar 3074 3198 3073 3081 ν(C-H)Ar 1670 1665 1728 1734 νC=O 1603 1605 1607 1606 νC=C 1506 1499 1539 1532 νN-CS 1343 1390 1381 1471 νN-CO - - 1346 1359 νN=O 1262 1258 1276 1270 νCS-N 861 875 858 890 νC=S 842 811 842 874 δC=S 778 793 729 796 νC-Br1 739 791 705 730 νC-Br2 701 742 700 686 νC-Br3 * ν: Stretching, δ: Bending. Figure 3. Molecular packing diagram of compound I. Moreover, the νN-H vibration peaks were observed for the thiourea group at 3112 and 3284 cm-1 for compounds I and II, respectively. Furthermore, the calculated values for the stretching vibrations were found to be 3617, 3515 and 3674, 3339 cm-1, respectively. Although the stretching vibrations of the carbonyl (νC=O) and thiocarbonyl (νC=S) groups as an experimental value were observed at 1670, 1728 cm-1 and 1343, 1454 cm-1, for compounds I and II, that of theoretical values was founded at 1665, 1734 cm-1 and 1390, 1471 cm-1, respectively. Furthermore, the presence of the bending vibra- tion of the C = S group for the title compounds was identified by the observed peak at 861 and 858 cm-1 [30]. 160 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Figure 4. Molecular packing diagram of compound II. Figure 5. Experimental and simulated FT-IR spectra of compound I. Figure 6. Experimental and simulated FT-IR spectra of compound II. Vibration bands with wavenumbers of 3099, 3074 and 3180, 3073 cm-1 (νC-H, Ar-H); 1603 and 1607 cm-1 (νC=C); 1506 and 1539 cm-1 (νN-CSthioureido), 1262 and 1276 cm-1 (νCS-N) were confirmed the title compounds I and II, respectively. The O-NO stretching vibration was observed at 1346 cm-1 for the title compound II [31]. The stretching of the C-Br bonds in the compounds was confirmed at 778, 739, 701 cm-1 and 729, 705, and 700 cm-1, respectively. These stretching bands of the C-Br bonds were also calculated as 791, 793, 742 cm-1, and 796, 730, 686 cm-1 for compounds I and II, respectively. All conclusions agree with the literature [32,33]. 3.2.2. NMR analysis In most compounds containing electronegative atoms, N-H values are observed around δ 12 ppm due to hydrogen bond formation [34]. In 1H NMR, the characteristic broad singlet peaks appeared at δ 12.08, 12.25 ppm and 11.94, 11.86 ppm, for amide protons (NHa) and thio-amide protons (NHb) confirmed the structure of the new compounds I and II, respectively [35- 37]. For the title compounds I and II, the aromatic proton peaks of the phenyl ring and the 4-nitrophenyl ring could be observed at δ 7.56 ppm (t, 1H, -Hd), 7.69 (t, 2H, -He), 8.02 (d, 2H, -Hc) and Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 161 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Compound I Compound II O Ha N N S Hb 12.08 11.94 Hf BrHc Hd He 8.04 8.04 8.02 7.56 7.69 Br Br H O Ha N N S Hb 12.25 11.86 He Br Hc Hd O2N 7.99 7.99 8.31 Br Br H 8.17 O N H N H S 168.0 Br 131.7 136.9 125.0 Br Br 133.3 121.4 128.5 134.2 180.7 128.74 O N H N H S 167.0 Br O2N 134.7 138.8 123.9 Br Br 130.9 122.0 125.5 137.4 180.9 150.4 Scheme 2. The 1H NMR and 13C NMR chemical shifts of the title compounds I and II in DMSO-d6. Compound I Compound II Figure 7. The Mulliken atomic charge distribution of compounds I and II in the gas phase. 8.17 (d, 2H, -Hd), 8.31 ppm (d, 2H, -Hc), respectively. Further- more, two similar proton peaks of the 2,4,6-tribromo-phenyl ring of compounds I and II were observed at δ 8.04 (s, 2H, Hf) and 7.99 ppm (s, 2H, He), respectively. In the 13C NMR spectra of title compounds I and II, the signals observed in the region of δ 168.0 and 167.0 ppm and δ 180.7 and δ 180.9 ppm clearly describe the C=O and C=S carbons, respectively. Additionally, the peaks observed in the aromatic region confirmed the structures (Scheme 2). 3.3. Mulliken atomic charge analysis Because atomic charges determine the dipole moment, the molecular polarization and bond properties of a molecule. The calculation of the Mulliken atomic charge plays an important role [38]. The Mulliken population analysis was performed using the DFT/B3LYP calculation method with 6-311+G(d,p) basis set for the title compounds. Graphical reorientations of the Mulliken charge distribution of the title compounds I and II are shown in Figure 7. The hydrogen atoms are all positively charged, but those bonded to the nitrogen atoms are the most positively charged. Similarly, the nitrogen atoms conjugated with the carbonyl and thiocarbonyl groups of the title compounds I and II are highly negative charges (-0.392, -0.414 esu and -0.407, -0.418 esu), respectively, while the nitrogen atom of the nitro group of compound II has a positive charge (0.186 esu). In compounds I and II, it has been observed that the carbon atoms in the phenyl ring to which it is attached have a negative charge, while the bromine atoms have very little positive charge 0.004-0.017 esu and 0.009-0.027 esu, respect- tively. The highest positive atomic charge was 0.466 in compound I, but also with 0.492 compound II has a higher positive carbon atom charge of the carbonyl group. Therefore, carbonyl groups are a reactive moiety in these compounds. 3.4. Molecular electrostatic potential (MEP) The molecular electrostatic potential (MEP) helps interpret detailed information about many properties of a compound, such as chemical reactivity or biological activity. The spatial distribution and values of the electrostatic potential determine the attack regions of an electrophilic or nucleophilic unit on the molecule [39]. 162 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Compound I Compound II Figure 8. Molecular electrostatic potential (MEP) maps calculated of the title compounds I and II at B3LYP/6-311G(d,p) level. ELUMO = -2.2939 eV ELUMO = -3.1891 eV ΔE = 3.8133 eV ΔE = 3.4950 eV EHOMO = -6.1072 eV EHOMO = -6.6841 eV Compound I Compound II Figure 9. HOMO-LUMO plot of compounds I and II. The total electronic density and the MEP surface of the title molecules are constructed using the B3LYP/6-311G (d,p) method and are shown in Figure 8. Electronegative and electropositive regions of the MEP surface are identified by the color scheme. The red color is rich in electrons and partially negatively charged; yellow and green are defined as neutral ranges and blue is defined as the electron-deficient, partially positive charge region [40]. These MEP maps for compounds I and II show that the sulfur atom, as well as the carbonyl oxygen atom, is a possible site for electrophilic attack due to the tribromophenyl ring, and the nucleophilic attack sites are located on the hydrogen atoms bonded to nitrogen atoms. These MEP maps for compounds I and II show that the S atom, as well as the carbonyl O atom, is a possible site for electrophilic attack due to the tribromophenyl ring, and the nucleophilic attack sites are located on the hydrogen atoms bonded to nitrogen atoms. The results show that the most reactive region of these compounds is the region containing the sulfur atom, and provide information about the region where the compound may have intermolecular hydrogen bond interactions. Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 163 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Table 6. Frontier orbital energy, HOMO-LUMO energy gap, ionization potential (I), electron affinity (A), chemical potential (μ), chemical hardness (η), absolute softness (ζ), absolute electronegativity (χ), chemical potential (μ), and electrophilicity index (ω) of title compounds for ground state geometries in gas phase at B3LYP/6-311G(d,p) level. Parameters B3LYP/6-311G(d,p) Compound I Compound II Electronic energy (a.u.) -17688.9911 -9049.0604 EHOMO (eV) -6.1072 -6.6841 ELUMO (eV) -2.2939 -3.1891 Ionization energy, I = -EHOMO (eV) 6.1072 6.6841 Electron affinity, A = -ELUMO (eV) 2.2939 3.1891 Energy band gap, ΔE = EHOMO-ELUMO (eV) 3.8133 3.4950 Chemical hardness, η = (I-A)/2 (eV) 1.9066 1.7475 Chemical softness, ζ = 1/2η (eV-1) 0.2622 0.2861 Electronegativity, χ = (I+A)/2 (eV) 4.2005 4.9366 Chemical potential, μ = - (I+A)/2 (eV) -4.2005 -4.9366 Electrophilicity index, ω = μ²/2η (eV) 4.6271 6.9728 Compound I Compound II Figure 10. Thermodynamic parameters of compounds I and II. 3.5. Frontier molecular orbitals analysis Frontier molecular orbitals (FOMs), known as the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), contain information on the chemical stability of the molecule [41]. Active regions can be predicted by the distribution of the frontier orbital since the HOMO implies the electron-donating capacity of a molecule and the LUMO indicates the electron-accepting capacity of a molecule [42]. The HOMO-LUMO plots of the two molecules are shown in Figure 9. The negative and positive phases are colored red and green. As shown in Figure 9, the HOMO electrons are localized around the entire tribromophenyl and connected thiourea moiety, while for LUMO, the electrons are distributed entirely over the aroyl ring and the thiourea moiety for the title compounds. The electron-withdrawing or donating groups influence the HOMO and LUMO energies. Electron-withdrawing groups, such as nitro groups, reduce the energy of the LUMO while affecting the HOMO slightly less. It has been described that a molecule with a small frontier orbital space can be more polarizable and is generally associated with high chemical reactivity and low kinetic stability, and is called a soft molecule [43]. Global reactivity, such as Frontier orbital energy, HOMO-LUMO energy gap, chemical potential (µ), chemical hardness (η), global electrophilicity index (ω), and chemical softness (ς) were calculated using the B3LYP/6-311G(d,p) method and is listed in Table 6. The energy values of the HOMO and LUMO of the title compounds (I, II) were calculated as -6.1072 eV (HOMO), - 6.2569 eV (HOMO-1), -2.2939 eV (LUMO), -2.0563 eV (LUMO- 1) and -6.6841 eV (HOMO), -6.9641 eV (HOMO-1), -3.1891 eV (LUMO), -1.9157 eV (LUMO+1), respectively (Table 6). According to these data, the energy gap values for compounds I and II are calculated as 3.8133 eV and 3.4950 eV. When comparing the energy gap values of the title compounds, compound II is more chemically reactive and unstable than compound I because the energy gap is narrower due to the effect of the nitro group [44-45]. From Table 6, when the chemical hardness and softness values of compounds I and II (1.7475 eV, 0.2861 eV and 1.9066 eV, 0.2622 eV, respectively) are compared, it is emphasized that compound II is more reactive than compound II [46]. 3.6. Thermodynamic properties Thermodynamic quantum chemical data becomes important to study the reaction processes of organic compounds [47]. Thermodynamic parameters for different temperatures were calculated at the B3LYP/6-311G (d,p) level and scaled by 0.96. Three main thermodynamic properties as heat capacity 𝐶𝐶𝑝𝑝.𝑚𝑚 ° , enthalpy 𝛥𝛥𝛥𝛥𝑚𝑚0 and entropy 𝑆𝑆𝑚𝑚° for compounds I and II are plotted in Figures 10a and 10b. As shown in Figure 10, all values increase as the temperature increases in the range of 100-1000 K. The correlation equation of 𝐶𝐶𝑝𝑝.𝑚𝑚 ° , 𝑆𝑆𝑚𝑚° , 𝛥𝛥𝛥𝛥𝑚𝑚0 and temperature are as follows for title compounds I and II, respectively: 𝐶𝐶𝑝𝑝,𝑚𝑚 ° (I) = 26.5639 + 0.4899 T -2.3069×10-4 T2 (R2 = 0.9992) (1) 𝑆𝑆𝑚𝑚° (I) = 112.2255 + 0.6415 T – 1.93958×10-4 T2 (R2 = 0.9996) (2) 𝛥𝛥𝛥𝛥𝑚𝑚0 (I) = -7.5617 + 0.0884 T + 7.4451×10-6 T2 (R2 = 0.9993) (3) 𝐶𝐶𝑝𝑝.𝑚𝑚 ° (II) = 13.7884 + 0.2660 T -1.279×10-4 T2 (R2 = 0.9991) (4) 𝑆𝑆𝑚𝑚° (II) = 79.7534 + 0.3501 T – 1.0782×10-4 T2 (R2 = 0.9996) (5) 𝛥𝛥𝛥𝛥𝑚𝑚0 (II) = -4.2287 + 0.0491 T + 6.1967×10-5 T2 (R2 = 0.9993) (6) Additionally, for both title compounds, all calculated thermodynamic parameters (𝐶𝐶𝑝𝑝.𝑚𝑚 ° , 𝑆𝑆𝑚𝑚° , 𝛥𝛥𝛥𝛥𝑚𝑚0 ) appear to increase 0 100 200 300 400 500 600 0 100 200 300 400 500 600 700 800 900 1000 1100 ∆H m ⁰ , C ⁰p ,m , S m ⁰ Temperature (K) Cp S H 0 50 100 150 200 250 300 350 400 0 100 200 300 400 500 600 700 800 900 1000 1100 ∆H m ⁰ , C ⁰p ,m , S m ⁰ Temperature (K) Cp S H 164 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 with increasing temperature due to the increase in molecular vibration. 4. Conclusions In this study, two novel N-benzoyl-N'-tribromophenyl thiourea (I) and 4-nitrobenzoyl-N'-tribromophenylthiourea (II) have been synthesized and investigated by elemental analysis, FT-IR, 1H NMR, 13C NMR, and X-ray diffraction techniques. The crystal structures of compounds I and II showed intramolecular and intermolecular interactions with centers that are hydrogen-bond donors and hydrogen-bond acceptors. The presence of electron donors such as S, N, and O in these compounds emphasizes their polydentate ligand properties. This property would cause compounds I and II to exhibit polydentate ligand properties with respect to various metals in terms of coordination chemistry. Theoretical calculations of these compounds have also been performed using the density functional theory method with the B3LYP/6-311G(d,p) basis set. Although the differences in the geometric parameters are observed, the general agreement is in a good range and the theoretical calculations support the solid-state structures. The experimental vibrational frequencies agree with the results of the B3LYP method. The calculated MEP maps verify the intramolecular hydrogen-bond interactions in the solid state. HOMO and LUMO’s come into existence with π-antibonding type orbitals. It is clear from the global reactivity data that compound I (X = H) is hard and more stable or less reactive, while compound II (X = NO2) is soft and less stable. Acknowledgements The authors are grateful to Prof. Kadir Aslan at Morgan State University, Baltimore, USA, for his financial support. Supporting information CCDC-2160417 (Compound I) and 2160418 (Compound II) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by e- mailing data_request@ccdc.cam.ac.uk, or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(0)1223-336033. Disclosure statement Conflict of interest: The authors declare that they have no conflict of interest. Ethical approval: All ethical guidelines have been adhered to. Sample availability: Samples of the compounds are available from the author. CRediT authorship contribution statement Conceptualization: Fatma Aydin; Methodology: Fatma Aydin; Software: Nahide Burcu Arslan; Formal Analysis: Nahide Burcu Arslan; Investigation: Fatma Aydin; Data Curation: Fatma Aydin, Nahide Burcu Arslan; Writing - Original Draft: Fatma Aydin; Writing - Review and Editing: Fatma Aydin, Nahide Burcu Arslan; Visualization: Fatma Aydin, Nahide Burcu Arslan; Supervision: Fatma Aydin; Project Administration: Fatma Aydin. ORCID and Email Nahide Burcu Arslan burcu.arslan@giresun.edu.tr https://orcid.org/0000-0002-1880-1047 Fatma Aydin faydin@comu.edu.tr https://orcid.org/0000-0002-7219-6407 References [1]. Özgeriş, B. Design, synthesis, characterization, and biological evaluation of nicotinoyl thioureas as antimicrobial and antioxidant agents. J. Antibiot. (Tokyo) 2021, 74, 233–243. [2]. Rana, A.; Siddiqui, N.; Khan, S. A.; Ehtaishamul Haque, S.; Bhat, M. A. N- [(6-Substituted-1,3-benzothiazole-2-yl)amino]carbonothioyl-2/4- substituted benzamides: Synthesis and pharmacological evaluation. Eur. J. Med. Chem. 2008, 43, 1114–1122. [3]. Asghar, F.; Rana, S.; Fatima, S.; Badshah, A.; Lal, B.; Butler, I. S. Biologically activehalo-substituted ferrocenyl thioureas: synthesis, spectroscopic characterization, and DFT calculations. New J Chem 2018, 42, 7154–7165. [4]. Soni, L. K.; Narsinghani, T.; Jain, R. Synthesis and antibacterial screening of some 1-aroyl-3-aryl thiourea derivatives. ISRN Med. Chem. 2014, 2014, 1–6, 393102. [5]. Duan, L.-P.; Xue, J.; Xu, L.-L.; Zhang, H.-B. Synthesis 1-Acyl-3-(2’- aminophenyl) thioureas as Anti-Intestinal Nematode Prodrugs. Molecules 2010, 15, 6941–6947. [6]. Shaabanzadeh, M.; Khabari, F. One-pot diastereoselective synthesis of new spiro indenoquinoxaline derivatives containing cyclopropane ring. ARKIVOC 2009, 2009, 307–315. [7]. Aydın, F.; Ünver, H.; Aykaç, D.; İskeleli, N. O. Spectroscopic studies and structure of 4-(3-benzoylthioureido)benzoic acid. J. Chem. Crystallogr. 2010, 40, 1082–1086. [8]. Ozer, C. K.; Binzet, G.; Arslan, H. Crystal and molecular structure of bis(N-(diethylcarbamothioyl)cyclohexane carboxamido)copper(II) complex. Eur. J. Chem. 2020, 11, 319–323. [9]. Solmaz, U.; Gumus, I.; Binzet, G.; Celik, O.; Balci, G. K.; Dogen, A.; Arslan, H. Synthesis, characterization, crystal structure, and antimicrobial studies of novel thiourea derivative ligands and their platinum complexes. J. Coord. Chem. 2018, 71, 200–218. [10]. Luckay, R. C.; Mebrahtu, F.; Esterhuysen, C.; Koch, K. R. Extraction and transport of gold(III) using some acyl(aroyl)thiourea ligands and a crystal structure of one of the complexes. Inorg. Chem. Commun. 2010, 13, 468–470. [11]. Aydin, F.; Aykaç, D.; Burcu Arslan, N.; Kazak, C. Synthesis, characterization, and crystal structure of bis[4-(3′-benzoyl) thiocarbamidophenyl]ether. Crystallogr. Rep. 2014, 59, 955–960. [12]. Contreras Aguilar, E.; Echeverría, G. A.; Piro, O. E.; Ulic, S. E.; Jios, J. L.; Tuttolomondo, M. E.; Molina, R. D. I.; Arena, M. E. Acyl thiourea derivatives: A study of crystallographic, bonding, biological and spectral properties. Chem. Phys. Lett. 2019, 715, 64–71. [13]. Aydin, F.; Arslan, N. B. Synthesis, crystal structure and cyclic voltammetric behavior of N-aroyl-N′-(4′-cyanophenyl)thioureas. Molbank 2022, 2022, M1316. [14]. Pinter, B.; Fievez, T.; Bickelhaupt, F. M.; Geerlings, P.; De Proft, F. On the origin of the steric effect. Phys. Chem. Chem. Phys. 2012, 14, 9846. [15]. Geiger, T.; Haupt, A.; Maichle-Mössmer, C.; Schrenk, C.; Schnepf, A.; Bettinger, H. F. Synthesis and photodimerization of 2- and 2,3- disubstituted anthracenes: Influence of steric interactions and London dispersion on diastereoselectivity. J. Org. Chem. 2019, 84, 10120–10135. [16]. Audu, O. Y.; Jooste, J.; Malan, F. P.; Ajani, O. O.; October, N. Synthesis, characterization, molecular structure, and computational studies on 4(1H)-pyran-4-one and its derivatives. J. Mol. Struct. 2021, 1245, 131077. [17]. Udofia, I. A.; Trust Ekama; Ogunbayo, T. B.; Oloba-Whenu, O. A.; Rhyman, L.; Isanbor, C.; Ramasami, P. Experimental and theoretical calculation of pKa values of substituted-2,4,6-trinitrodiphenylamines. J. Mol. Liq. 2023, 371, 120926. [18]. Sheldrick, G. M. SHELXS-97 and SHELXL-97 Program for Crystal Structure Solution and Refinement. University of Gottingen, Germany, Germany, 1997. [19]. Farrugia, L. J. WinGX and ORTEP for Windows: an update. J. Appl. Crystallogr. 2012, 45, 849–854. [20]. Becke, A. D. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 1993, 98, 5648–5652. [21]. Lee, C.; Yang, W.; Parr, R. G. Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B Condens. Matter 1988, 37, 785–789. [22]. Ditchfield, R.; Hehre, W. J.; Pople, J. A. Self-consistent molecular-orbital methods. IX. An extended Gaussian-type basis for molecular-orbital studies of organic molecules. J. Chem. Phys. 1971, 54, 724–728. [23]. Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A.; Vreven, T.; Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K; Foresman, J. B.; Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.; Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; http://www.ccdc.cam.ac.uk/data_request/cif mailto:data_request@ccdc.cam.ac.uk mailto:burcu.arslan@giresun.edu.tr https://orcid.org/0000-0002-1880-1047 mailto:faydin@comu.edu.tr https://orcid.org/0000-0002-7219-6407 Arslan and Aydin / European Journal of Chemistry 15 (2) (2024) 155-165 165 2024 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.15.2.155-165.2551 Wong, M. W.; Gonzalez, C.; Pople, J. A. Gaussian09, Gaussian, Inc., Wallingford CT, 2009. [24]. Molecular electrostatic potentials: Volume 3: Concepts and applications; Murray, J. S.; Sen, K., Eds.; Elsevier Science: London, England, ISBN: 978-0-444-82353-3, 1996. [25]. Andersson, M. P.; Uvdal, P. New scale factors for harmonic vibrational frequencies using the B3LYP density functional method with the triple-ζ basis set 6-311+G(d,p). J. Phys. Chem. A 2005, 109, 2937–2941. [26]. Dennington, R.; Keith, T. A.; Millam, J. M. GaussView, Version 5, Semichem Inc.; Shawnee Mission, KS, 2009. [27]. Threlfall, T. The infrared spectra of amides. Part 1. The stretching vibrations of primary carboxamides. Vib. Spectrosc. 2022, 121, 103386. [28]. Larkin, P. Infrared and Raman spectroscopy: Principles and spectral interpretation; Elsevier Science Publishing: Philadelphia, PA, 2018. [29]. Hassan, I. N. Synthesis, spectral characterization and crystal structural of 1-(2-Morpholinoethyl)-3-(3-phenylacryloyl)thiourea. Int. J. Phys. Sci. 2011, 6. [30]. Estévez-Hernández, O.; Otazo-Sánchez, E.; Hidalgo-Hidalgo de Cisneros, J. L.; Naranjo-Rodríguez, I.; Reguera, E. A Raman and infrared study of 1-furoyl-3-monosubstituted and 3,3-disubstituted thioureas. Spectrochim. Acta A Mol. Biomol. Spectrosc. 2005, 62, 964–971. [31]. Kirishnamaline, G.; Magdaline, J. D.; Chithambarathanu, T.; Aruldhas, D.; Anuf, A. R. Theoretical investigation of structure, anticancer activity and molecular docking of thiourea derivatives. J. Mol. Struct. 2021, 1225, 129118. [32]. Asghar, F.; Fatima, S.; Rana, S.; Badshah, A.; Butler, I. S.; Tahir, M. N. Synthesis, spectroscopic investigation, and DFT study of N,N′- disubstituted ferrocene-based thiourea complexes as potent anticancer agents. Dalton Trans. 2018, 47, 1868–1878. [33]. Khurshid, A.; Saeed, A.; Shabir, G.; Gil, D. M.; Bolte, M.; Erben, M. F. Synthesis of phenazone based carboxamide under thiourea reaction conditions. Molecular and crystal structure, Hirshfeld surface analysis and intermolecular interaction energies. J. Mol. Struct. 2023, 1278, 134948. [34]. Hansen, P. E.; Vakili, M.; Kamounah, F. S.; Spanget-Larsen, J. NH stretching frequencies of intramolecularly hydrogen-bonded systems: An experimental and theoretical study. Molecules 2021, 26, 7651. [35]. Qiao, L.; Zhang, Y.; Hu, W.; Guo, J.; Cao, W.; Ding, Z.; Guo, Z.; Fan, A.; Song, J.; Huang, J. Synthesis, structural characterization and quantum chemical calculations on 1-(isomeric methylbenzoyl)-3-(4- trifluoromethylphenyl)thioureas. J. Mol. Struct. 2017, 1141, 309–321. [36]. Saeed, A.; Khurshid, A.; Bolte, M.; Fantoni, A. C.; Erben, M. F. Intra- and intermolecular hydrogen bonding and conformation in 1-acyl thioureas: An experimental and theoretical approach on 1-(2- chlorobenzoyl)thiourea. Spectrochim. Acta A Mol. Biomol. Spectrosc. 2015, 143, 59–66. [37]. Özer, C. K.; Arslan, H.; VanDerveer, D.; Külcü, N. Synthesis and characterization of N-(arylcarbamothioyl)-cyclohexanecarboxamide derivatives: The crystal structure of N-(naphthalen-1- ylcarbamothioyl)cyclohexanecarboxamide. Molecules 2009, 14, 655– 666. [38]. Mulliken, R. S. Electronic population analysis on LCAO–MO molecular wave functions. I. J. Chem. Phys. 1955, 23, 1833–1840. [39]. Scrocco, E.; Tomasi, J. Electronic molecular structure, reactivity and intermolecular forces: An euristic interpretation by means of electrostatic molecular potentials. In Advances in Quantum Chemistry Volume 11; Elsevier, 1978; pp. 115–193. [40]. Toro-Labbé, A. Theoretical aspects of chemical reactivity; Elsevier Science: London, England, 2007. [41]. Pearson, R. G. Chemical hardness and density functional theory. J. Chem. Sci. (Bangalore) 2005, 117, 369–377. [42]. Xu, Y.; Chu, Q.; Chen, D.; Fuentes, A. HOMO–LUMO gaps and molecular structures of polycyclic aromatic hydrocarbons in soot formation. Front. Mech. Eng. 2021, 7. [43]. Fleming, I. Molecular orbitals and organic chemical reactions; Wiley, New York, 2010. [44]. Türker, L. Interaction of TNT and aluminum – A DFT treatment. Z. Anorg. Allg. Chem. 2015, 641, 408–413. [45]. Gökalp, F. A theoretical investigation of TNT in different phases by using DFT. Turkish Computational and Theoretical Chemistry 2019, 3, 1–4. [46]. Miar, M.; Shiroudi, A.; Pourshamsian, K.; Oliaey, A. R.; Hatamjafari, F. Theoretical investigations on the HOMO–LUMO gap and global reactivity descriptor studies, natural bond orbital, and nucleus- independent chemical shifts analyses of 3-phenylbenzo[d]thiazole- 2(3H)-imine and its para-substituted derivatives: Solvent and substituent effects. J. Chem. Res. 2021, 45, 147–158. [47]. Jean-Pierre, L. The role and the status of thermodynamics in quantum chemistry calculations. In Thermodynamics - Interaction Studies - Solids, Liquids and Gases; InTech, ISBN: 978-953-307-563-1, 2011. Copyright © 2024 by Authors. This work is published and licensed by Atlanta Publishing House LLC, Atlanta, GA, USA. The full terms of this license are available at https://www.eurjchem.com/index.php/eurjchem/terms and incorporate the Creative Commons Attribution-Non Commercial (CC BY NC) (International, v4.0) License (http://creativecommons.org/licenses/by-nc/4.0). By accessing the work, you hereby accept the Terms. This is an open access article distributed under the terms and conditions of the CC BY NC License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited without any further permission from Atlanta Publishing House LLC (European Journal of Chemistry). No use, distribution, or reproduction is permitted which does not comply with these terms. Permissions for commercial use of this work beyond the scope of the License (https://www.eurjchem.com/index.php/eurjchem/terms) are administered by Atlanta Publishing House LLC (European Journal of Chemistry). https://www.eurjchem.com/index.php/eurjchem/terms http://creativecommons.org/licenses/by-nc/4.0 https://www.eurjchem.com/index.php/eurjchem/terms 1. Introduction 2. Experimental 2.1. Material and measurements 2.2. Synthesis and characterization 2.3. X-ray data collection and structure refinement 2.4. Computational procedures 3. Results and discussion 3.1. Description of the crystal structure 3.2. Spectral analysis 3.2.1. Vibrational spectra 3.2.2. NMR analysis 3.3. Mulliken atomic charge analysis 3.4. Molecular electrostatic potential (MEP) 3.5. Frontier molecular orbitals analysis 3.6. Thermodynamic properties 4. Conclusions Acknowledgements Supporting information Disclosure statement CRediT authorship contribution statement ORCID and Email References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField15: PrintField16: PrintField17: PrintField18: PrintField19: PrintField110: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: PrintField25: PrintField26: PrintField27: PrintField28: PrintField29: PrintField210: