Synthesis, crystal structure, Hirshfeld surface analysis, and DFT studies on (2,2’-bipyridine)chlorobis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) comple European Journal of Chemistry 13 (1) (2022) 91-98 European Journal of Chemistry ISSN 2153-2249 (Print) / ISSN 2153-2257 (Online) – Copyright © 2022 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.13.1.91-98.2212 European Journal of Chemistry View Journal Online View Article Online Synthesis, crystal structure, Hirshfeld surface analysis, and DFT studies on (2,2’-bipyridine)chlorobis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato- S,S’)zinc(II) complex Soundararajan Eswari and Subbiah Thirumaran * Department of Chemistry, Faculty of Science, Annamalai University, Annamalainagar 608 002, India * Corresponding author at: Department of Chemistry, Faculty of Science, Annamalai University, Annamalainagar 608 002, India. e-mail: sthirumaran@yahoo.com (S. Thirumaran). 10.5155/eurjchem.13.1.91-98.2212 Received: 15 November 2021 Received in revised form: 20 December 2021 Accepted: 26 December 2021 Published online: 31 March 2022 Printed: 31 March 2022 Bis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (1) and (2,2’- bipyridine)chlorobis(N,N-bis(thiophen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (2) were synthesized. Complex 2 (final product) was structurally characterized by single crystal X-ray diffraction studies. Complex 2 (C21H18ClN3S4Zn) crystallized in triclinic crystal system with space group P-1 (no. 2), a = 8.7603(4) Å, b = 10.7488(6) Å, c = 13.0262(7) Å, α = 103.965(2)°, β = 91.913(2)°, γ = 104.944(2)°, V = 1144.07(10) Å3, Z = 2, T = 302(2) K, μ(MoKα) = 1.569 mm-1, Dcalc = 1.572 g/cm3, 14892 reflections measured (4.838° ≤ 2Θ ≤ 56.52°), 5570 unique (Rint = 0.0188, Rsigma = 0.0230) which were used in all calculations. The final R1 was 0.0810 (I > 2σ(I)) and wR2 was 0.2788 (all data). Complex 2 displays distorted square pyramidal coordination geometry. Crystal structure analysis of complex 2 shows that the crystal packing is mainly stabilized by C-H···π (chelate) and C-H···Cl interactions. Hirshfeld surface analysis was carried out to explore deeply into the nature and type of non- covalent interactions. The molecular and electronic structures of complexes 1 and 2 were also studied by DFT quantum chemical calculations. Ligand IR spectroscopy Crystal structure Zinc(II) dithiocarbamate Density functional theory Hirshfeld surface analysis Cite this: Eur. J. Chem. 2022, 13(1), 91-98 Journal website: www.eurjchem.com 1. Introduction Nowadays, a wide range of chemistry explored and deve- loped around the dithiocarbamates and their metal complexes draws attraction due to their unique chemistry and numerous applications [1-3]. The structural chemistry of group 12 dithio- carbamates has attracted the attention of structural chemistry for past two decades due to their diversity structure and supramolecular association in solid state. There are several structural motifs such as monomeric, dimeric, trimeric, linear chain, and layer motifs that have been reported for group 12 dithiocarbamate complexes [4-6]. Systematic studies indicated that the structures of group 12 dithiocarbamates are influenced by N-bound organic moiety [7,8], the solvent used for crystallization [9], and crystallization time [10]. However, the common structural motif adopted by zinc(II) dithiocarbamates is the one that features chelating ligands and two tridentate ligands leading to a centrosymmetric dimer. Addition of imine ligands (such as pyridine, 2,2’-bipyridine, or 1,10-phenon- throline) to zinc(II) dithiocarbamates, the dimeric motifs are disrupted, resulting in the formation of monomeric imine adducts of zinc(II) dithiocarbamates [11,12]. Due to these interesting structural variations and applications, in this paper, we report synthesis and DFT studies on complexes bis(N,N- bis(thiophen-2-ylmethyl)dithiocarbamato-S, S’)zinc(II) comp- lex (1) and (2,2’-bipyridine)chlorobis(N,N-bis(thiophen-2-yl methyl)dithiocarbamato-S,S’)zinc(II) complex (2). In addition, the crystal structure and Hirshfeld surface analysis of complex 2 are also presented. 2. Experimental 2.1. Material and methods 2-Thiophenemethylamine and 2-thiophenemethylaldehyde were purchased from Sigma-Aldrich. Zinc sulphate and 2,2’- bipyridine were obtained from Qualigens and SD Fine Chemicals, respectively. All other reagents and solvents were purchased from commercial sources and were used without further purification. FT-IR spectra were recorded in an Agilent- Cary 650 infrared spectrometer in the frequency range 4000- 600 cm-1. Single crystal X-ray diffraction measurements of complex 2 were performed using a Bruker D8 QUEST APEX (III) diffractometer (MoKα, λ = 0.71073 Å, Graphite monochro- mator). ABSTRACT RESEARCH ARTICLE KEYWORDS https://dx.doi.org/10.5155/eurjchem.13.1.91-98.2212 https://www.eurjchem.com/ https://dx.doi.org/10.5155/eurjchem.13.1.91-98.2212 mailto:sthirumaran@yahoo.com http://www.eurjchem.com/ https://crossmark.crossref.org/dialog/?doi=10.5155/eurjchem.13.1.91-98.2212&domain=pdf&date_stamp=2022-03-31 92 Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 Table 1. Crystal data and structure refinement for complex 2. Empirical formula C21H18ClN3S4Zn Formula weight 541.44 Temperature (K) 302(2) Crystal system Triclinic Space group P-1 a, (Å) 8.7603(4) b, (Å) 10.7488(6) c, (Å) 13.0262(7) α (°) 103.965(2) β (°) 91.913(2) γ (°) 104.944(2) Volume (Å3) 1144.07(10) Z 2 ρcalc (g/cm3) 1.572 μ (mm-1) 1.569 F(000) 552.0 Crystal size (mm3) 0.33 × 0.27 × 0.25 Radiation MoKα (λ = 0.71073) 2Θ range for data collection (°) 4.838 to 56.52 Index ranges -11 ≤ h ≤ 11, -13 ≤ k ≤ 14, -17 ≤ l ≤ 17 Reflections collected 14892 Independent reflections 5570 [Rint = 0.0188, Rsigma = 0.0230] Data/restraints/parameters 5570/0/271 Goodness-of-fit on F2 1.083 Final R indexes [I≥2σ (I)] R1 = 0.0810, wR2 = 0.2681 Final R indexes [all data] R1 = 0.0891, wR2 = 0.2788 Largest diff. peak/hole (e.Å-3) 2.32/-1.31 S O H MeOH NaBH2 MeOH/CH2Cl2 ZnSO4.7H2O CS2/EtOH N N 2,2'-Bipyridine NH2S SS H NSS N S S Zn S S N S S Zn S S S S N S S N Cl 1 2 SS H N Scheme 1. Preparation of complexes 1 and 2. Using Olex2 [13], the structure was solved by direct methods using the SHELXT 2014/5 [14] program and refined by full-matrix least square on F2 with SHEXL 2018/3 [15], assuming anisotropic displacement parameters for non- hydrogen atoms. All hydrogen atoms were fixed geometrically. Experimental features related to the X-ray analysis of complex 2 are given in Table 1. 2.2. Theoretical studies All DFT calculations were carried out for complex 1 and 2 using Gaussian 03 [16]. The molecular structures of complexes 1 and 2 in the ground state were optimized by using DFT method using B3LYP hybrid functional [17] combined with LANL2DZ basis set. The Hirshfeld surface analysis has also been carried out for complex 2 using CrystalExplorer 3.1 program [18,19]. 2.3. Synthesis of complexes Bis(thiophen-2-ylmethyl)amine was prepared using the method reported in the literature [20,21]. Bis(thiophen-2- ylmethyl)amine was prepared by 30 mL of methanol solution containing 2-thiophenemethylamine (0.5 mL, 4.6 mmol) and thiophene-2-carboxaldehyde (0.5 mL, 5.3 mmol) were stirred at room temperature for 2 h. Then sodium borohydride (499 mg, 13.18 mmol) was added and stirred for 1 h at ice-cold condition. While the reaction mixture was stirred for overnight at room temperature. The secondary amine was separated using dichloromethane (20 mL) solvent. 2.3.1. Synthesis of bis(N,N-bis(thiophen-2-ylmethyl) dithiocarbamato-S,S’)zinc(II) complex (1) Bis(thiophene-2-ylmethyl)amine (0.7 mL, 4.0 mmol) was dissolved in 20 mL of ethanol. To this solution, carbon disulfide (0.3 mL, 4.0 mmol) was added dropwise with constant stirring. Yellow dithiocarbamic acid solution was obtained. An aqueous solution of ZnSO4.7H2O (575 mg, 2.0 mmol) was added to this solution. The solid product was collected by filtration and dried in a desiccator (Scheme 1). Bis(N, N-bis(thiophen-2-ylmethyl)dithiocarbamato-S, S’) zinc(II) complex (1): Color: White. Yield: 65%. M.p.: 195-197 °C. FT-IR (KBr, ν, cm-1): 1474 (vC–N), 975 (vC–S). Anal. calcd. for C22H20N2S8Zn: C, 41.66; H, 3.18; N, 4.42. Found: C, 41.45; H, 3.14; N, 4.38%. Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 93 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 Table 2. Geometric details of hydrogen bonding (Å, °) in complex 2. Interactions D–H H∙∙∙A D∙∙∙A ∠ D–H∙∙∙A C2–H2AB∙∙∙S1 a 0.970 2.568 3.029 109.2 C21–H21∙∙∙S1 a 0.930 2.969 3.532(7) 119.5 C7–H7AB∙∙∙S2 a 0.970 2.481 3.002(6) 113.4 C19–H19∙∙∙S1 b 0.930 3.064 3.818(7) 139.4 C6-H6∙∙∙Cl1 c 0.930 2.919 3.83(1) 165.9 C12-H12∙∙∙Cl1 c 0.930 2.938 3.720(7) 142.9 C15-H15∙∙∙Cl1 c 0.930 2.950 3.590 127.2 C20-H20∙∙∙Cl1 c 0.930 2.913 3.771(9) 154.0 C26-H26∙∙∙π (C3, C4, C5, C6, S4) d 0.969 2.778 3.473 129.25 C26-H26∙∙∙π (Zn1, S1, S2, C1) e 0.930 2.992 3.626 126.71 a Intramolecular C–H∙∙∙S interaction. b Intermolecular C–H∙∙∙S interaction. c Intermolecular C–H∙∙∙Cl interaction. d C–H∙∙∙π interactions (pyrrole ring). e C-H∙∙∙π (chelate) interaction. Figure 1. Molecular structure of complex 2. 2.3.2. Synthesis of (2,2’-bipyridine)chlorobis(N,N-bis(thio phen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (2) Complex 1 (634 mg, 1 mmol) and 2,2’-bipyridine (312 mg, 2 mmol) were dissolved in hot chloroform (30 mL) and ethanol (10 mL), respectively. The latter hot solution was added dropwise in to the hot chloroform solution. To the resulting yellow solution, petroleum ether (100 mL) was added. The yellow precipitate obtained was filtered and washed with ethanol and dried in a desiccator. The product was recrystallized from chloroform:acetonitrile (3:1, v:v) solution. The chloride ion present in the product presumably arises from chloride extraction from the chloroform. Similar chloride extraction from solvent was observed in the reaction of Hg(S2CNEt2)2 and 4,7-Me2-Phen in chloroform to form [Hg(S2CNEt2)Cl (4,7-Me2-Phen)] [22] (Scheme 1). (2, 2’-Bipyridine)chlorobis(N, N-bis(thiophen-2-ylmethyl)di thiocarbamato-S,S’)zinc(II) complex (2): Color: Yellow. Yield: 52%. M.p.: 200-202 °C. FT-IR (KBr, ν, cm-1): 1437 (vC–N), 966 (vC– S). Anal. calcd. for C21H18ClN3S4Zn: C, 46.58; H, 3.35; N, 7.76. Found: C, 46.38; H, 3.28; N, 7.68%. 3. Results and discussion 3.1. IR spectral studies IR spectra of metal dithiocarbamate complexes displayed two characteristic strong bands due to νC-N (thioureide) and νC- S stretching vibrations. In the present study, IR spectra of complexes 1 and 2 show νC-N (thioureide) frequencies at 1474 and 1437 cm-1, respectively, which indicates that C-N bond is intermediate between single and double bond [23]. The νC-S vibrational band was observed as a single band at 975 and 966 cm-1 in the spectra of complexes 1 and 2, respectively, indica- ting a bidentate coordination of the ligand to the metal center [24]. 3.2. Structural analysis of complex 2 Zinc atom in complex 2 has a distorted square pyramid geometry, being asymmetrically chelated by one N,N- bis(thiophen-2-ylmethyl)dithiocarbamate ligand and symmet- rically chelated by one 2,2’-bipyridine ligand in the equatorial plane while the fifth coordination site in an axial position is occupied by a chloride ion (Figure 1). The chelate rings defined by Zn1, S1, S2, C1 and Zn1, N4, N5, C16, C17 atoms show a small bite angle deviating 17.84 and 13.4°, respectively, from the ideal angle 90°. As a result, the trans angles (N4-Zn1-S2=135.62(12)° and N5-Zn1-S1=149.10°) subtended, thus significantly deviating from the ideal trans angle of 180°. In the present structure, τ computes to 0.22 which is nearer to an ideal square pyramidal geometry (τ = 0) than to one ideal trigonal bipyramidal with τ = 1.0. The presence of acute ligand bite angles (S1-Zn-S2 = 72.16(4)° and N4-Zn1-N5 = 76.58(18)°) is partially responsible for the observed distortion. The C1-S1 (1.713(5) Å) and C1-S2 (1.725 (5) Å) bond lengths are intermediate between a single and double bond length, thus exhibiting the delocalization of electron density over the NCS2 unit [25]. The most prominent feature of the molecular packing is the formation of linear chain. The association between molecules is of the type π (chelate) ring···H, whereby the chelate centroid (Zn1, S1, S2, C1)-H19 separation is 2.992 Å (Figure 2a and Table 2). Such C-H···π (chelate) interactions are well documented [26] in the literature for metal-dithiocarbamate complexes. Crystal structure is further stabilized by intermolecular non- covalent interactions of the C-H···π (thiophene ring) nature. The adjacent molecules are linked together with numerous weak C-H···Cl intramolecular interactions generating a three- dimensional network (Figure 2b). 94 Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 Figure 2. (a) Intermolecular C-H···π (chelate) interaction and (b) Intermolecular C-H···Cl interaction in complex 2. Figure 3. The dnorm values were mapped with a white-blue-red colors scheme using Hirshfeld surface of complex 2. 3.3. Hirshfeld surface analysis The supramolecular interactions in complex 2 were further investigated and visualized by Hirshfeld surface analysis [27]. Figure 3 shows the Hirshfeld surface of complex 2 mapped over dnorm. The deep-red circular depressions represent inter- molecular short S···H and Cl···H contacts. The finger plots complement the Hirshfeld surface, quantitatively summarizing the nature and type of the intermolecular contacts by describing atom (inside)/atom (outside) interactions (Figure 4). The most significant contributions to the Hirshfeld surface are from H···H (36.5%), C···H/H···C (20.6%), S···H/H···S (15.6%) and Cl···H/H···Cl (12.8%) contacts. These interactions play a crucial role in the overall stabilization of the crystal packing. Other contacts (e.g, S···C/C···S, C···C, N···H/H···N, S···N/N···S, S···S, N···C/C···N and Zn···H/H···Zn) make contribution of less than 4.5% to the Hirshfeld surface [28]. 3.4. Optimized geometry Geometries of complexes 1 and 2 have been fully optimized and are shown in Figure 5. Selected structural parameters are listed in Table 3. The calculated structural parameters for complex 1 are well in consistent with the corresponding values reported for similar monomeric zinc(II) dithiocarbamate complexes [29]. The bond lengths and bond angles of the optimized geometry of complex 2 are compared with those determined using X-ray diffraction (Table 3). The correlation graphs between the calculated and experimental parameters of bond length and bond angles of complex 2 are calculated as R2 = 0.98 and 0.99 for bond lengths and bond angles, respectively, which indicate the good agreement between the calculated and experimental bond parameters. 3.5. Molecular electrostatic potential (MEP) Molecular electrostatic potential of complexes 1 and 2 and the surface maps were developed and are shown in Figure 6. The electric potential diminishes in the following order: red > orange > yellow > green > blue. The electrophilic and nucleo- philic sites of a molecule can be distinguished using these different colors [30,31]. In complex 1, the negative potential regions are located on both sulfur atoms of NCS2 moiety and the positive regions are located over carbon atoms of NCH2 groups and hydrogen atoms of thiophene rings. The strongest negative and positive potentials are mainly related to one sulfur atom (orange) and another sulfur atom (blue) of NCS2, respectively, in complex 2. All other atoms have slight positive potential (green). 3.6. Frontier molecular orbitals The frontier molecular orbitals of complexes 1 and 2 are shown in Figure 7. Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 95 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 Table 3. Selected bond length and bond angles in complexes 1 and 2. Bond distances (Å) (1) DFT Bond distances (Å) (2) XRD DFT Bond angles (°) (2) XRD DFT 52N-7C 1.3513 Zn1-N4 2.105(4) 2.1762 N4-Zn1-N5 76.58(18) 75.47 7C-2S 1.7994 Zn1-N5 2.161(4) 2.1997 N4-Zn1-Cl1 107.63(12) 114.86 7C-3S 1.8004 Zn1-Cl1 2.3053(12) 2.3269 N5-Zn1-Cl1 104.45(12) 96.62 2S-1Zn 2.4913 Zn1-S2 2.3856(15) 2.5591 N4-Zn1-S2 135.62(12) 117.58 3S-1Zn 2.4926 Zn1-S1 2.5917(15) 2.6816 N5-Zn1-S2 92.96(12) 92.47 Bond angles (°) (1) S1-C1 1.713(5) 1.7833 Cl1-Zn1-S2 116.74(5) 127.31 52N-7C-2S 121.23 S2-C1 1.725(5) 1.7938 N4-Zn1-S1 95.01(13) 95.38 52N-7C-3S 121.16 N3-C1 1.330(6) 1.3592 N5-Zn1-S1 149.10(12) 155.72 2S-7C-3S 117.60 Cl1-Zn1-S1 106.42(5) 108.59 7C-2S-1Zn 83.03 S2-Zn1-S1 72.16(4) 71.59 7C-3S-1Zn 82.98 C1-S1-Zn1 82.08(16) 83.23 2S-1Zn-3S 76.32 C1-S2-Zn1 88.34(17) 86.73 2S-1Zn-5S 127.86 N3-C1-S1 122.3(4) 121.28 3S-1Zn-4S 128.29 N3-C1-S2 120.4(4) 120.65 5S-1Zn-4S 76.38 S1-C1-S2 117.3(3) 118.05 Figure 4. The two-dimensional fingerprint plots for complex 2 interactions and delineated into H···H, C···H, S···H, Cl···H, S···C, C···C, and N···H interactions. (a) (b) Figure 5. The optimized molecular structure for complexes 1 (a) and 2 (b). The energy gap between HOMO and LUMO can be used as an indicator of kinetic stability, chemical reactivity, and optical polarizability [32]. In complex 1, the HOMO is localized in CS2 moiety, whereas the electronic density of the LUMO is mainly situated in both S atoms of dithiocarbamate ligands. It is observed that in complex 2, HOMO is located mainly over both sulfur atoms of NCS2 and Cl, whereas LUMO is located mainly as 2,2’-bipyridine. The values of the energy gap of complexes 1 and 2 are 4.8401 and 2.6589 eV. These values indicate that complex 1 is more stable than complex 2 and less reactive [24]. 96 Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 Table 4. Global chemical reactivity parameters for complexes 1 and 2. Parameter (eV) Complex 1 Complex 2 Energy (a.u) -30099.0062 -29829.3962 EHOMO -6.3245 -5.5011 ELUMO -1.4844 -2.8422 Energy Gap 4.8401 2.6589 Ionization potential (IP) 6.3245 5.5011 Electron affinity (EA) 1.4844 2.8422 Absolute electronegativity (χ) 3.9045 4.1717 Absolute softness (σ) 0.4132 0.7522 Chemical hardness (η) 2.4201 1.3295 Chemical potential (μ) -3.9045 -4.1717 Electrophilicity (ω) 3.1458 6.5450 -3.914e-2 3.914e-2 (a) -1.084e-2 1.804e-2 (b) Figure 6. MEP map of (a) complexes 1 and (b) 2. ELUMO = -1.4844 eV ↕ EGAP = 4.8401 eV EHOMO = -6.3245 eV ELUMO = -2.8422 eV ↕ EGAP = 2.6589 eV EHOMO = - 5.5011 eV Figure 7. Frontier molecular orbitals (FMOs) of (a) complex 1 and (b) complex 2. The global reactivity descriptors of complexes 1 and 2 such as absolute electronegativity (χ), softness (σ), hardness (η), chemical potential (μ), and electrophilicity (ω), are obtained using the following equations [32]: χ = (I+A)/2, σ = 1/η, η = (I- A)/2, μ = - χ, ω = μ2/2η Where I = -EHOMO and A = -ELUMO are the ionization potential and electron affinity, respectively. The Global reactivity descriptors values are given in Table 4. Complex 1 showed a higher chemical hardness (2.4201 eV) than that of complex 2 (1.3295 eV). This indicates that complex 1 resist more towards the deformation of the electron density distribution, hence more stable and less reactive compared to complex 2 [33]. The higher electrophilicity index value of complex 2 indicates that it is the strong electrophile compared to complex 1 [34]. 4. Conclusions Synthesis and characterization of complexes 1 and 2 were presented. Crystal structure of complex 2 showed that zinc(II) is five-coordinated in a distorted square pyramid in complex 2. The mononuclear (2,2’-bipyridine)chlorobis(N,N-bis(thiophen- 2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (2) form the Eswari and Thirumaran / European Journal of Chemistry 13 (1) (2022) 91-98 97 2022 – European Journal of Chemistry – CC BY NC – DOI: 10.5155/eurjchem.13.1.91-98.2212 multidimensional frame work by the help of C-H···π (chelate) and C-H···Cl interactions. Hirshfeld surface analysis of complex 2 confirmed the presence of C-H···Cl intermolecular interac- tions. 2-D finger print plots of complex 2 showed that the major contribution to the total Hirshfeld surface is from H···H (36.5%) contacts. Molecular structures of complexes 1 and 2 were studied using DFT calculations. There is a good agreement between the calculated bond parameters for complex 2 with those derived from the X-ray crystal structure. Acknowledgements Support is acknowledged from the donors of the American Chemical Society Petroleum Research Fund (PRF# 12345-AC1); the State of Delaware; the National Institute of General Medical Sciences (P20GM123456) from the National Institutes of Health (INBRE program); and a National Science Foundation (NSF) EPSCoR grant IIA-1234567. Supporting information CCDC-2121961 contains 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. Sample availability: Samples of the compounds are available from the author. CRediT authorship contribution statement Conceptualization: Subbiah Thirumaran; Methodology: Subbiah Thirumaran; Software: Soundararajan Eswari; Validation: Soundararajan Eswari; Formal Analysis: Soundararajan Eswari; Investigation: Soundararajan Eswari, Subbiah Thirumaran; Resources: Subbiah Thirumaran; Data Curation: Soundararajan Eswari; Writing - Original Draft: Soundararajan Eswari; Writing - Review and Editing: Subbiah Thirumaran; Visualization: Soundararajan Eswari; Supervision: Subbiah Thirumaran; ORCID and Email Soundararajan Eswari eswariphd1625@gmail.com https://orcid.org/0000-0002-9089-0814 Subbiah Thirumaran sthirumaran@yahoo.com https://orcid.org/0000-0002-5771-5328 References [1]. Maurya, V. K.; Singh, A. K.; Singh, R. P.; Yadav, S.; Kumar, K.; Prakash, P.; Prasad, L. B. Synthesis and Evaluation of Zn(II) Dithiocarbamate Complexes as Potential Antibacterial, Antibiofilm, and Antitumor Agents. J. Coord. Chem. 2019, 72 (19–21), 3338–3358. [2]. Alam, M. N.; Mandal, S. 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R.; Ríos-Gutiérrez, M.; Pérez, P. A Molecular Electron Density Theory Study of the Participation of Tetrazines in Aza-Diels– Alder Reactions. RSC Adv. 2020, 10 (26), 15394–15405. Copyright © 2022 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 http://www.eurjchem.com/index.php/eurjchem/pages/view/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 (http://www.eurjchem.com/index.php/eurjchem/pages/view/terms) are administered by Atlanta Publishing House LLC (European Journal of Chemistry). http://www.eurjchem.com/index.php/eurjchem/pages/view/terms http://creativecommons.org/licenses/by-nc/4.0 http://www.eurjchem.com/index.php/eurjchem/pages/view/terms 1. Introduction 2. Experimental 2.1. Material and methods 2.2. Theoretical studies 2.3. Synthesis of complexes 2.3.1. Synthesis of bis(N,N-bis(thiophen-2-ylmethyl) dithiocarbamato-S,S’)zinc(II) complex (1) 2.3.2. Synthesis of (2,2’-bipyridine)chlorobis(N,N-bis(thio phen-2-ylmethyl)dithiocarbamato-S,S’)zinc(II) complex (2) 3. Results and discussion 3.1. IR spectral studies 3.2. Structural analysis of complex 2 3.3. Hirshfeld surface analysis 3.4. Optimized geometry 3.5. Molecular electrostatic potential (MEP) 3.6. Frontier molecular orbitals 4. Conclusions Acknowledgements Supporting information Disclosure statement CRediT authorship contribution statement ORCID and Email References PrintField10: PrintField11: PrintField12: PrintField13: PrintField14: PrintField15: PrintField16: PrintField17: PrintField20: PrintField21: PrintField22: PrintField23: PrintField24: PrintField25: PrintField26: PrintField27: