untitled European Journal of Chemistry 7 (4) (2016) 416‐420 European Journal of Chemistry ISSN 2153‐2249 (Print) / ISSN 2153‐2257 (Online)  2016 Atlanta Publishing House LLC ‐ All rights reserved ‐ Printed in the USA http://dx.doi.org/10.5155/eurjchem.7.4.416-420.1503 European Journal of Chemistry Journal webpage: www.eurjchem.com Crystal structure of cis‐copper(II) complex with N‐(di‐n‐propylcarbamothioyl)cyclohexanecarboxamide ligand Ilkay Gumus 1,*, Cemal Koray Ozer 1, Don Vanderveer 2 and Hakan Arslan 1 1 Department of Chemistry, Faculty of Arts and Science, Mersin University, Mersin, TR 33343, Turkey 2 Department of Chemistry, Clemson University, Clemson, SC 29634‐0973, USA * Corresponding author at: Department of Chemistry, Faculty of Arts and Science, Mersin University, Mersin, TR 33343, Turkey. Tel.: +90.538.5589656. Fax: +90.324.3610047. E‐mail address: ilkay.gumus@mersin.edu.tr (I. Gumus) ARTICLE INFORMATION ABSTRACT DOI: 10.5155/eurjchem.7.4.416-420.1503 Received: 29 October 2016 Received in revised form: 11 November 2016 Accepted: 11 November 2016 Published online: 31 December 2016 Printed: 31 December 2016   Copper(II) complex, cis‐[Cu(L‐κ2S,O)2] of N‐(di‐n‐propylcarbamothioyl)cyclohexane carboxamide ligands (HL) has been synthesized and structurally characterized by various spectroscopic techniques and single crystal X‐ray diffraction crystallography. The cis‐[Cu(L‐ κ2S,O)2], C28H50CuN4O2S2: Monoclinic, space group P21/n (no. 14), a = 10.025(2) Å, b = 21.724(4) Å, c = 14.848(3) Å, β = 100.60(3)°, Z = 4, Dcalc = 1.259 g/cm3, 22069 reflections measured (5.88° ≤ 2Θ ≤ 50.2°), 5639 unique (Rint = 0.0630, Rsigma = 0.0678) which were used in all calculations. The final R1 was 0.0488 (≥2σ(I)) and wR2 was 0.1277 (all data). Single crystal analysis revealed that a square‐planar coordination geometry is formed around the copper atom by two sulphur and two oxygen atoms of the related ligand, which are in a cis configuration. KEYWORDS Thioureas Cis‐complex Copper complex Single crystal structure Carboxamide derivatives Cyclohexanecarboxamide Cite this: Eur. J. Chem. 2016, 7(4), 416‐420 1. Introduction Acyl substituted thioureas were first synthesized by Neucki [1]. These ligand systems of thioureas are attractive scaffolds for several reasons (I) potential applications in a wide range of fields are being investigated and (II) these compounds are easily synthesized in high yields. Many acyl thiourea derivatives are well known as collectors in froth flotation processes [2,3] and as ionophores in ion‐selective electrodes [4‐6]. At the same time some of them are display a wide range of biological activity including insecticidal, herbicidal, antibacterial, antifungal, antitubercular, antithroid, antihelmintic, rodenticidal and plant‐growth regulator properties [7‐10]. Thiourea derivative ligands are tend to coordinate to both transition group and main group metal ions via both sulfur and oxygen providing a multitude of bonding possibilities [11‐13]. Copper(II) complexes of acyl thiourea ligands have been described repeatedly in the literature with regard to their synthesis and general characterization [14‐16] and molecular structures [17‐20]. These copper(II) complexes are in every case nearly square‐planar neutral bis chelates with a cis arrangement of the ligands around the copper atom. In this study, we describe the single crystal structures of N‐(di‐ n‐propylcarbamothioyl)cyclohexanecarboxamide ligand based copper(II) complex. 2. Experimental 2.1. Instrumentation Melting points were recorded on electrothermal model 9200 apparatus. Carbon, hydrogen and nitrogen analyses were carried out on a Carlo Erba MOD 1106 elemental analyzer. Infrared measurement was recorded in the range 400‐4000 cm−1 on a Perkin Elmer Spectrum 100 series FT‐IR/FIR/NIR Spectrometer Frontier, ATR Instrument. The NMR spectra were recorded in CDCl3 solvent on Bruker Avance III 400 MHz NaNoBay FT‐NMR spectrophotometer using tetramethylsilane as an internal standard. Crystallographic measurements of the compound were carried out at 153(2) K using a Bruker APEX‐II CCD area‐ detector diffractometer. The intensity data were collected using graphite monochromated MoKα radiation, λ = 0.71073 Å. Absorption corrections were applied with the program SADABS [21]. The structure was solved by direct methods SHELXS‐97 [22], and refined by full‐matrix least‐squares techniques on F2 using SHELXL‐97 with refinement of F2 against all reflections. Gumus et al. / European Journal of Chemistry 7 (4) (2016) 416‐420 417 Scheme 1 Scheme 2 Hydrogen atoms were constrained by difference maps and were refined isotropically, and all non‐hydrogen atoms were refined anisotropically. The molecular structure plots were prepared using OLEX2 [23]. The anisotropic thermal para‐ meters and structure factors (observed and calculated), full list of bond distances, bond angles and torsional angles are given in supplementary materials. The geometric special details: all e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.’s are taken into account individually in the estimation of e.s.d.’s in distances, angles and torsion angles; correlations between e.s.d.’s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.’s is used for estimating e.s.d.’s involving l.s. planes. 2.2. Reagents The cyclohexanecarbonyl chloride, copper(II) acetate were purchased from Sigma Aldrich. Potassium thiocyanate and di‐ n‐propylamine were purchased from Merck and used as received. All other chemicals and solvents were obtained from commercial suppliers and used without further purification. 2.3. Synthesis of the ligand The ligand was prepared according to procedure reported in the literature [24]. A solution of cyclohexanecarbonyl chloride (0.005 mole) in acetone (30 mL) was added dropwise to a suspension of potassium thiocyanate (0.005 mole) in acetone (30 mL). The reaction mixture was heated (50 °C) under reflux for 30 min, and then cooled to room temperature. A solution of di‐n‐propylamine (0.005 mole) in acetone (30 mL) was added and the resulting mixture was stirred for 2 h. Hydrochloric acid (0.1 N, 100 mL) was added and the solution filtered. The solid product was washed with water and purified by recrystallization from an ethanol:dichloromethane mixture (1:2, v:v) (Scheme 1). N‐(Di‐n‐propylcarbamothioyl)cyclohexane carboxamide (HL): Color: White. Yield: 85%. M.p.: 121‐122 °C. Anal. calcd. for C14H26N2OS: C, 62.18; H, 9.69; N, 10.36. Found: C, 62.70; H, 9.60; N, 10.40 %. FT‐IR (ATR, ν, cm‐1): ν(NH) 3231 (w), ν(CH) 2959, 2924, 2856 (w), ν(C=O) 1655 (s), ν(C=S) 1313 (s). 1H NMR (400 MHz, CDCl3, δ, ppm): 7.89 (s, 1H, NH), 3.85 (t, 2H, NCH2), 3.38 (t, 2H, NCH2), 2.22 (tt, 1H, CH, ch), 1.89 (d, 1H, CH, ch), 1.79 (d, 1H, CH, ch), 1.78 (m, 1H, CH, ch), 1.75 (m, 1H, CH, ch), 1.66 (m, 1H, CH, ch), 1.62 (m, 1H, CH, ch), 1.42 (m, 4H, CH, ch), 1.32‐1.12 (m, 4H, NCH2CH2), 0.94 (t, 3H, CH3), 0.84 (t, 3H, CH3). 2.4. Synthesis of the copper(II) complex The copper(II) complex was prepared according to the method described [25‐27]. The solution of ligand (10.0 mmol) in ethanol (50 mL) was added dropwise a solution of copper(II) acetate (10.0 mmol) in etanol (50 mL) at room temperature. The reaction mixture was stirred for 30 min, and then cooled to room temperature. A precipitate was formed which was filtered off and recrystallized from ethanol: dichloromethane mixture (2:1, v:v) (Scheme 2). Bis(N‐(di‐n‐propylcarbamothioyl)cyclohexanecarboxamido) copper(II), cis‐[Cu(L‐κ2S,O)2]: Color: Green. Yield: 86 %. M.p.: 78‐80 °C. Anal. calcd for C28H50N4O2S2Cu: C, 55.83; H, 8.37; N, 9.30. Found: C, 56.80; H, 8.50; N, 9.20%. FT‐IR (ATR, ν, cm‐1): ν(CH) 2963, 2932, 2852 (s), ν(CN) 1514 (s), ν(CO) 1481 (vs). 3. Result and discussion The cyclohexanecarbonyl chloride reacted with a potas‐ sium thiocyanate in acetone. This reaction resulted in the formation of cyclohexanecarbonyl isothiocyanate. The product could be used for the next step without purification. Then the cyclohexanecarbonyl isothiocyanate reacted with di‐n‐ propylamine. The resulting product N‐(di‐n‐propylcarbamo thioyl)cyclohexanecarboxamide was purified by recrystal‐ lization from an ethanol:dichloromethane mixture and charac‐ 418 Gumus et al. / European Journal of Chemistry 7 (4) (2016) 416‐420 Table 1. Crystal data and details of the structure refinement for cis‐[Cu(L‐κ2S,O)2]. Parameters Crystal formula C28H50CuN4O2S2 Formula weight 602.38 Temperature (K) 153(2) Crystal system Monoclinic Space group P21/n a, (Å) 10.025(2) b, (Å) 21.724(4) c, (Å) 14.848(3) β, (ᵒ) 100.60(3) Volume (Å3) 3178.5(11) Z 4 Dcalc (g cm‐1) 1.259 μ (mm‐1) 0.848 F (000) 1292.0 Crystal dimensions (mm3) 0.41 × 0.24 × 0.10 Radiation Mo Kα (λ = 0.71073) 2Θ range for data collection (°) 5.88 to 50.2 Index ranges ‐10 ≤ h ≤ 11, ‐25 ≤ k ≤ 25, ‐17 ≤ l ≤ 17 Reflections collected 22069 Independent reflections 5639 [Rint = 0.0630, Rsigma = 0.0678] Data/restraints/parameters 5639/0/338 GOF 1.054 Final R indexes [I≥2σ (I)] R1 = 0.0488, wR2 = 0.1104 Final R indexes [all data] R1 = 0.0779, wR2 = 0.1277 () min ‐() max (e Å‐3) 0.56 ‐ 0.38 Figure 1. Molecular structure of cis‐[Cu(L‐κ2S,O)2] with the atom numbering scheme. Displacement ellipsoids are shown at the 50 % probability level. terized by elemental analyses, 1H NMR, 13C NMR and FT‐IR spectroscopy. Scheme 1 shows the pathway for the synthesis of the ligand. The reaction of the ligands with copper(II) acetate at room temperature in ethanol as solvent yielded the complex. Scheme 2 shows the pathway for the synthesis of the copper(II) complex. The metal complex was recrystallized from ethanol:dichloromethane mixture and characterized by various spectroscopic techniques and also by X‐ray crystallography. Data of all synthesized compounds confirm the proposed structures. The IR spectra of prepared ligand was showed charac‐ teristic band at 3231 cm−1 corresponding to ν(NH) stretching bond. In addition, the strong ν(C=O) stretching vibration band was observed at 1655 cm−1. Moreover synthesized ligand show weak intensity ν(C=S) stretching vibration at the 1313 cm−1. The FT‐IR spectra of the copper(II) complex display important differences when compared with the FT‐IR spectra of the free ligand. The most important difference is the ν(NH) stretching band of free ligand disappeared completely in the spectrum of the copper(II) complex indicating the deprotonation of the NH group. The main vibrational bands of the investigated com‐ pounds are given in the experimental section. The signals belong to the NH group of the ligand was observed as a singlet at δ 7.89 ppm in the NMR spectrum. This peak does not appear in the copper(II) complex. All other proton signals of synthesized ligand and complex are appeared in appropriate place. The NMR data of the compounds are given in the experimental section. X‐ray diffraction quality crystals of cis‐[Cu(L‐κ2S,O)2] were grown from ethanol:dichloromethane mixture (1:1, v:v). The structure of copper complex was confirmed by the result of single crystal X‐ray diffraction determination. Single crystal X‐ ray analysis shows that complex, cis‐[Cu(L‐κ2S,O)2], belongs to monoclinic crystal system, space group P21/n. Relevant crystallographic data are presented in Table 1‐3. The mole‐ cular structure of cis‐[Cu(L‐κ2S,O)2] is shown in Figure 1. The results confirmed the connectivity of ligand to the metal in 2:1 and the square planar geometry around the metal centre (O2‐Cu1‐O1 87.61(11), O2‐Cu1‐S2 94.42(8), O1‐Cu1‐S2 157.47(8) and O2‐Cu1‐S1 155.91(8)°) (Table 3). In the complex, the ligand forms by coordination a bis chelate with cis arrangement of the donor atoms sulphur and oxygene. The Cu1‐S1, Cu1‐S2, Cu1‐O1 and Cu1‐O2 bond lengths are 2.2511(11), 2.2372(12), 1.938(3) and 1.930(2) Å, respectively, and Cu1‐S bond lengths are longer than Cu1‐O bond lengths (Table 2). This indicates the stronger bonding of the oxygen atom to Cu(II) than sulphur atom. Gumus et al. / European Journal of Chemistry 7 (4) (2016) 416‐420 419 Table 2. Selected bond lengths for cis‐[Cu(L‐κ2S,O)2]. Atom Atom Length (Å) Atom Atom Length (Å) Cu1 O2 1.930(2) C4 C5 1.519(6) Cu1 O1 1.938(3) C5 C6 1.516(6) Cu1 S2 2.2372(12) C8 C9 1.513(5) Cu1 S1 2.2511(11) C9 C14 1.521(5) S1 C7 1.739(4) C9 C10 1.528(6) S2 C21 1.740(4) C10 C11 1.528(5) O1 C8 1.273(4) C11 C12 1.524(6) O2 C22 1.270(4) C12 C13 1.515(7) N1 C7 1.339(5) C13 C14 1.520(6) N1 C4 1.467(5) C15 C16 1.507(5) N1 C1 1.485(5) C16 C17 1.527(5) N2 C8 1.325(5) C18 C19 1.511(5) N2 C7 1.341(5) C19 C20 1.535(5) N3 C21 1.342(4) C22 C23 1.520(5) N3 C15 1.473(4) C23 C24 1.529(5) N3 C18 1.478(4) C23 C28 1.539(5) N4 C22 1.315(5) C24 C25 1.528(5) N4 C21 1.340(5) C25 C26 1.521(6) C1 C2 1.517(6) C26 C27 1.513(6) C2 C3 1.519(6) C27 C28 1.539(5) Table 3. Selected bond angles for cis‐[Cu(L‐κ2S,O)2]. Atom Atom Atom Angle (°) Atom Atom Atom Angle (°) O2 Cu1 O1 87.61(11) N2 C8 C9 114.7(3) O2 Cu1 S2 94.42(8) C8 C9 C14 113.6(3) O1 Cu1 S2 157.47(8) C8 C9 C10 111.7(3) O2 Cu1 S1 155.91(8) C14 C9 C10 110.5(4) O1 Cu1 S1 95.08(8) C9 C10 C11 110.4(3) S2 Cu1 S1 92.14(4) C12 C11 C10 111.2(3) C7 S1 Cu1 99.27(13) C13 C12 C11 111.7(4) C21 S2 Cu1 102.14(13) C12 C13 C14 111.7(4) C8 O1 Cu1 128.4(3) C13 C14 C9 111.0(3) C22 O2 Cu1 130.4(2) N3 C15 C16 113.3(3) C7 N1 C4 120.4(3) C15 C16 C17 111.9(3) C7 N1 C1 124.3(3) N3 C18 C19 113.2(3) C4 N1 C1 115.2(3) C18 C19 C20 110.7(3) C8 N2 C7 124.8(3) N4 C21 N3 115.1(3) C21 N3 C15 123.6(3) N4 C21 S2 126.7(3) C21 N3 C18 120.8(3) N3 C21 S2 117.9(3) C15 N3 C18 115.6(3) O2 C22 N4 128.4(3) C22 N4 C21 124.9(3) O2 C22 C23 116.0(3) N1 C1 C2 112.2(3) N4 C22 C23 115.4(3) C1 C2 C3 109.3(3) C22 C23 C24 110.7(3) N1 C4 C5 111.9(3) C22 C23 C28 111.8(3) C6 C5 C4 112.0(3) C24 C23 C28 110.5(3) N1 C7 N2 114.9(3) C25 C24 C23 111.0(3) N1 C7 S1 119.3(3) C26 C25 C24 110.9(3) N2 C7 S1 125.7(3) C27 C26 C25 111.8(3) O1 C8 N2 127.5(3) C26 C27 C28 111.7(3) O1 C8 C9 117.7(3) C27 C28 C23 110.2(3) Figure 2. The chair conformation and bond angles of cyclohexane rings in synthesized copper(II) complex. The C7‐N1, N2‐C8, C7‐N2, N4‐C22, N4‐C21, and N3‐C21 bond lengths are 1.339(5), 1.325(5), 1.341(5), 1.315(5), 1.340(5) and 1.342(4) Å, respectively, and these bond lengths are shorther than the normal C‐N single bond (1.48 Å) and longer than normal C=N double bond (1.25 Å) [28]. But N1‐C4, N1‐C1, N3‐C15 and N3‐C18 bond lengths are 1.467(5), 1.485(5), 1.473(4) and 1.478(4) Å, respectively, and these bond distance are similar to the normal C‐N single bond [29‐36]. The double bond character of the carbonyl and thiocarbonyl groups when compare with literature results are weakened (C22‐O2 1.270(4), C8‐O1 1.273(4), C21‐S2 1.740(4) and C7‐S1 1.739(4) Å) due to the donation of electron to the metal centre. The cyclohexane rings (C9‐C10‐C11‐C12‐C13‐ C14 and C23‐C24‐C25‐C26‐C27‐C28) in the copper(II) comp‐ lex exhibits chair conformation as can be seen in Figure 2. In this conformation, all hydrogen atoms are staggered and all C‐ C‐C bond angles are nearly tetrahedral with a value of approximately at ∼111°. These bond angles are typical for chair conformation of cyclohexane ring [37]. The unit cell and packing of the complex is given in Figure 3. 420 Gumus et al. / European Journal of Chemistry 7 (4) (2016) 416‐420 Figure 3. The unit cell and packing of cis‐[Cu(L‐κ2S,O)2]. 4. Conclusions Cis‐copper(II) complex of N‐(di‐n‐propylcarbamothioyl) cyclohexanecarboxamide ligand has been successfully synthesized and characterized by a single‐crystal X‐ray diffraction study. Single crystal analysis revealed that the ligand forms by coordination a bis chelate with cis arrangement of the donor atoms sulphur and oxygene. Acknowledgements This study was supported by the Research Fund of Mersin University in Turkey with Project Number: BAP‐SBE TB (CKÖ) 2007‐1 YL. 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