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Journal of Chemistry
Volume 2013 (2013), Article ID 536562, 9 pages
http://dx.doi.org/10.1155/2013/536562
Research Article

Synthesis and Characterization of Novel Thiourea Derivatives and Their Nickel and Copper Complexes

1Department of Science Education, Faculty of Education, Mersin University, 33343 Mersin, Turkey
2Department of Physics, Faculty of Sciences, Dicle University, 21280 Diyarbakır, Turkey
3Department of Chemistry, Faculty of Arts and Science, Mersin University, 33343 Mersin, Turkey
4Department of Physics Engineering, Hacettepe University, Beytepe, 06800 Ankara, Turkey
5Department of Chemistry, University of Paderborn, 33098 Paderborn, Germany

Received 29 May 2013; Accepted 28 July 2013

Academic Editor: Andrea Trabocchi

Copyright © 2013 Gün Binzet et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

New benzoyl thiourea derivatives and their nickel and copper complexes were synthesized. The structure of the synthesized compounds were confirmed by elemental analysis, FT-IR, and 1H NMR techniques. Four of the synthesized compounds are analyzed by X-ray single crystal diffraction technique. Whereas N,N-dimethyl-N′-(4-fluorobenzoyl)thiourea, N,N-diethyl-N′-(4-fluorobenzoyl)thiourea, and N,N-di-n-butyl-N′-(4-fluorobenzoyl) thiourea crystallize in the monoclinic system, bis(N,N-di-n-propyl-N′-(4-fluorobenzoyl)thioureato) nickel(II) complex crystallizes in the triclinic system. These ligand molecules form dimers through strong intermolecular hydrogen bonds such as N–HS, C–HO, and N–HO. Moreover, there are different types of intramolecular interactions in the crystal structures. Bis(N,N-dimethyl-N′-(4-fluorobenzoyl)thioureato) nickel(II) complex has a nearly square-planar coordination. The distance of nickel atom from the best plane through the coordination sphere is 0.029 Å.

1. Introduction

The role of benzoyl thioureas derivatives in coordination chemistry has been extensively studied and quite satisfactory elucidated. Because benzoyl thioureas have suitable C=O and C=S function groups, they can be considered as useful chelating agents due to their ability to encapsulate into their coordinating moiety metal ions [1]. Therefore, new thiourea derivatives and their structures have received attention of several research groups because of their complexation capacity [25]. Some derivatives are biologically active, such as antifungal [6, 7], antitumour [810], antiviral, antibacterial [1113], pharmacological [14], herbicidal, and insecticidal properties [1113]. In addition, some of the research groups have reported thermal behaviour [1518] and the acidity constants [19] of ligands of some benzoylthiourea derivatives and their metal complexes [2030].

In addition, fluorine-containing organic compounds have been frequently applied to biorelated materials, medicines, and agrochemicals because of their unique properties, such as high thermal stability and lipophilicity [20].

There are many reasons for the interest in such molecules. In the present study, we combined thiourea group with fluorine-containing organic compound and report the preparation and characterization of five new N,N-dialkyl-N-(4-fluorobenzoyl) thiourea compounds (alkyl: methyl (HL1), ethyl (HL2), n-propyl (HL3), n-butyl (HL4), and phenyl (HL5)) which include a fluorine atom and their Ni(II) and Cu(II) complexes (Scheme 1). The crystal and molecular structures of HL1, HL2, HL4, and Ni(L3)2 were characterized by single crystal X-ray diffraction.

536562.sch.001
Scheme 1: Synthesized compounds.

2. Experimental

2.1. Instrumentation

Melting points were recorded on electrothermal model 9200 apparatus. C, H, and N analyses were carried out on a Carlo Erba MOD 1106 elemental analyzer. Infrared measurement was recorded in the range 400–4000 cm−1 on Satellite FT-IR equipped with a WINFIRST LITE software package form Mattson Instruments. The 1H NMR spectrums were recorded in CDCl3 solvent on Bruker-400 MHz spectrophotometer using tetramethylsilane as an internal reference. Single crystal X-ray diffraction data were collected on an Enraf-Nonius CAD 4 diffractometer and on a Bruker AXS SMART APEX CCD diffractometer using monochromated, MoKα (  Å) radiation.

2.2. Reagents

4-Fluorobenzoyl chloride, potassium thiocyanate, dimethylamine, diethylamine, di-n-propylamine, di-n-butylamine, and diphenylamine were purchased from Merck and used as received. Acetone and dichloromethane used without further purification. Ethanol was dried and distilled before the using.

2.3. General Procedure for the Synthesis of Ligands

A solution of 4-flourobenzoyl chloride (0.01 mol, 0.12 mL) in anhydrous acetone (50 mL) was added dropwise to a suspension of dry potassium thiocyanate (0.01 mol, 9718 g) in acetone (50 mL), and the reaction mixture was refluxed for 45 min. After cooling to room temperature, a solution of secondary amine (0.01 mol) in anhydrous acetone (50 mL) was added, and the resulting mixture refluxed for 2 h. Hydrochloric acid (0.1 M, 300 mL) was added, and the solution was filtered. The solid product was washed with water and purified by recrystallization from an ethanol : dichloromethane mixture (1 : 3) (Scheme 2).

536562.sch.002
Scheme 2: Synthesis of the ligands.

N,N-dimethyl-N′-4-fluoro benzoyl thiourea, (HL1): White. Yield: 78%. M.p.: 130–132°C. Anal. calcd. for C10H11FN2OS (%): C, 53.08; H, 4.90; N, 12.38. Found: C, 53.00; H, 4.81; N, 12.36. FT-IR (KBr pellet, cm−1): ν(NH) 3231, ν(CH) 2998, 2976, 2936, ν(C=O) 1668, ν(C=S) 1251, ν(C–F) 758. 1H NMR (400 MHz, CDCl3): 8.58 (s, 1H, NH), 7.74 (d, 2H, Ar–H), 7.64 (d, 2H, Ar–H), 3.51 (s, 3H, N–CH3), 3.26 (s, 3H, N–CH3).

N,N-diethyl-N′-4-fluoro benzoyl thiourea, (HL2): White. Yield: 88%. M.p.: 138–140°C. Anal. calcd. for C12H15FN2OS (%): C, 56.67; H, 5.94; N, 11.01. Found: C, 56.59; H, 5.91; N, 10.91. FT-IR (KBr pellet, cm−1): ν(NH) 3293, ν(CH) 2998, 2977, 2933, ν(C=O) 1647, ν(C=S) 1275, ν(C–F) 761. 1H NMR (400 MHz, CDCl3): 8.41 (s, 1H, NH), 7.88 (d, 2H, Ar–H), 7.16 (d, 2H, Ar–H), 4.04 (s, 2H, N–CH2), 3.70 (s, 2H, N–CH2), 1.38 (t, 3H, –CH3), 1.32 (t, 3H, –CH3).

N,N-di-n-propyl-N′-4-fluoro benzoyl thiourea, (HL3): White. Yield: 67%. M.p.: 78–80°C. Anal. calcd. for C14H19FN2OS (%): C, 59.55; H, 6.78; N, 9.92. Found: C, 59.51; H, 6.67; N, 9.91. FT-IR (KBr pellet, cm−1): ν(NH) 3271, ν(CH) 2968, 2934, 2877, ν(C=O) 1643, ν(C=S) 1275, ν(C–F) 753. 1H NMR (400 MHz, CDCl3): 8.42 (s, 1H, –NH), 7.86 (d, 2H, Ar–H), 7.15 (d, 2H, Ar–H), 3.92 (t, 2H, N–CH2), 3.51 (t, 2H, N–CH2), 1.83 (m, 2H, –CH2–), 1.71 (m, 2H, –CH2–), 1.02 (t, 3H, CH3), 0.88 (t, 3H, –CH3).

N,N-di-n-buthyl-N′-4-fluoro benzoyl thiourea, (HL4): White. Yield 89%. M.p.: 89–91°C. Anal. calcd. for C16H23FN2OS (%): C, 61.90; H, 7.47; N, 9.02. Found: C, 61.82; H, 7.41; N, 9.00. FT-IR (KBr pellet, cm−1): ν(NH) 3166, ν(CH) 2958, 2934, 2871, ν(C=O) 1685, ν(C=S) 1296, ν(C–F) 743. 1H NMR (400 MHz, CDCl3): 8.14 (s, 1H, –NH), 7.85 (d, 2H, Ar–H), 7.16 (d, 2H, Ar–H), 3.97 (s, 2H, N–CH2), 3.52 (s, 2H, N–CH2), 1.80 (m, 2H, –CH2), 1.67 (m, 2H, –CH2), 1.46 (m, 2H, –CH2), 1.30 (m, 2H, –CH2), 1.00 (t, 3H, –CH3), 0.92 (t, 3H, –CH3).

N,N-diphenyl-N′-4-fluoro benzoyl thiourea, (HL5): White. Yield 94%. M.p.: 149–151°C. Anal. calcd. for C20H15FN2OS (%): C, 68.55; H, 4.31; N, 7.99. Found: C, 68.48; H, 4.27; N, 7.92. FT-IR (KBr pellet, cm−1): ν(NH) 3159, ν(Ar–H) 3110, 3064, ν(C=O) 1690, ν(C=S) 1288, ν(C–F) 755. 1H NMR (400 MHz, CDCl3): 8.64 (s, 1H, –NH), 7.65 (m, 2H, Ar–H), 7.68 (m, 8H, Ar–H), 7.28 (m, 2H, Ar–H), 7.09 (m, 2H, Ar–H).

2.4. General Procedure for the Synthesis of Metal Complexes

The metal complexes were prepared according to a described method [2123]. A metal acetate solution in methanol was added dropwise to the ligand in a 1 : 2 molar ratio with a small excess of ligand in dichloromethane. The solid complex was filtered and recrystallized from ethanol : dichloromethane mixture (1 : 2) (Scheme 3).

536562.sch.003
Scheme 3: Synthesis of the metal complexes.

Bis(N,N-dimethyl-N′-4-fluoro benzoyl thioureato) nickel(II), (Ni(L1)2): Purple. Yield: 86%. M.p.: 257-258°C. Anal. calcd. for C20H20F2N4NiO2S2, (%): C, 47.17; H, 3.96; N, 11.00. Found: C, 47.10; H, 3.87; N, 11.01. FT-IR (KBr pellet, cm−1): ν(CH) 2929, 2853, ν(CN) 1602, ν(C–O), 1495, ν(C–F), 760. 1H NMR (400 MHz, CDCl3): 8.13 (m, 4H, Ar–H), 7.06 (m, 4H, Ar–H), 3.42 (s, 6H, N–CH3), 3.32 (s, 6H, N–CH3).

Bis(N,N-diethyl-N′-4-fluoro benzoyl thioureato) nickel(II), (Ni(L2)2): Purple. Yield: 77%. M.p.: 139-140°C. Anal. calcd. for C24H28F2N4NiO2S2 (%): C, 50.99; H, 4.99; N, 9.91. Found: C, 50.76; H, 4.91; N, 9.90. FT-IR (KBr pellet, cm−1): ν(CH) 2984, 2936, 2871, ν(CN) 1598, ν(C–O) 1494, ν(C–F) 766. 1H NMR (400 MHz, CDCl3): 8.12 (m, 4H, Ar–H), 7.06 (m, 4H, Ar–H), 3.79 (p, 8H, N–CH2), 1.27 (m, 12H, –CH3).

Bis(N,N-di-n-propyl-N′-4-fluoro benzoyl thioureato) nickel(II), (Ni(L3)2): Purple. Yield: 79%. M.p.: 155-156°C. Anal. calcd. for C28H36F2N4NiO2S2 (%): C, 54.12; H, 5.84; N, 9.02. Found: C, 53.97; H, 5.86; N, 9.07. FT-IR (KBr pellet, cm−1): ν(CH) 2963, 2929, 2871, ν(CN) 1600, ν(C–O) 1490, ν(C–F) 764. 1H NMR (400 MHz, CDCl3): 8.11 (m, 4H, Ar–H), 7.05 (m, 4H, Ar–H), 3.68 (m, 8H, N–CH2), 1.74 (m, 8H, CH2), 0.96 (m, 12H, –CH3).

Bis(N,N-di-n-buthyl-N′-4-fluoro benzoyl thioureato) nickel(II), (Ni(L4)2): Purple. Yield: 75%. M.p.: 148–150°C. Anal. calcd. for C32H44F2N4NiO2S2 (%): C, 56.73; H, 6.55; N, 8.27. Found: C, 56.61; H, 6.44; N, 8.21. FT-IR (KBr pellet, cm−1): ν(CH) 2956, 2929, 2866, ν(CN) 1600, ν(C–O) 1488, ν(C–F) 761. 1H NMR (400 MHz, CDCl3): 8.11 (m, 4H, Ar–H), 7.05 (m, 4H, Ar–H), 3.72 (m, 8H, N–CH2), 1.68 (m, 8H, CH2), 1.38 (m, 8H, CH2), 0.96 (m, 12H, CH3).

Bis(N,N-diphenyl-N′-4-fluoro benzoyl thioureato) nickel(II), (Ni(L5)2): Purple. Yield: 89%. M.p.: 317-318°C. Anal. calcd. for C40H28F2N4NiO2S2 (%): C, 63.42; H, 3.73; N, 7.40. Found: C, 63.30; H, 3.66; N, 7.33. FT-IR (KBr pellet, cm−1): ν(Ar–CH) 3100, 3086, ν(CN) 1599, ν(C–O) 1500, ν(C–F) 695. 1H NMR (400 MHz, CDCl3): 7.80–6.90 (m, 28H, Ar–H).

Bis(N,N-dimethyl-N′-4-fluoro benzoyl thioureato) copper(II), (Cu(L1)2): Green. Yield: 71%. M.p.: 209-210°C. Anal. calcd. for C20H20CuF2N4O2S2 (%): C, 46.73; H, 3.92; N, 10.90. Found: C, 46.61; H, 3.80; N, 10.77 FT-IR (KBr pellet, cm−1): ν(CH), 2926, 2852, ν(CN) 1600, ν(C–O) 1493, ν(C–F) 761.

Bis(N,N-diehtyl-N′-4-fluoro benzoylthioureato) copper(II), (Cu(L2)2): Green. Yield: 68%. M.p.: 143-144°C. Anal. calcd. for (%): C24H28CuF2N4O2S2: C, 50.56; H, 4.95; N, 9.83. Found: C, 50.39; H, 4.95; N, 9.81. FT-IR (KBr pellet, cm−1): ν(CH) 2985, 2933, 2868, ν(CN) 1598, ν(C–O) 1492, ν(C–F) 765.

Bis(N,N-di-n-propyl-N′-4-fluoro benzoyl thioureato) copper(II), (Cu(L3)2): Green. Yield: 76%. M.p.: 101-102°C. Anal. calcd. for C28H36CuF2N4O2S2, (%): Found: C, 53.70; H, 5.79; N, 8.95. Bulunan: C, 53.61; H, 5.71; N, 8.98. FT-IR (KBr pellet, cm−1): ν(CH) 2961, 2928, 2869, ν(CN) 1600, ν(C–O) 1485, ν(C–F) 766.

Bis(N,N-di-n-butyl-N′-4-fluorobenzoyl thioureato) copper(II), (Cu(L4)2): Green. Yield: 70%. M.p.: 112-113°C. Anal. calcd. for C32H44CuF2N4O2S2, (%): C, 56.32; H, 6.50; N, 8.21. Found: C, 56.19; H, 6.41; N, 8.20. FT-IR (KBr pellet, cm−1): ν(CH) 2958, 2929, 2857, ν(CN) 1600, ν(C–O) 1488, ν(C–F) 766.

Bis(N,N-diphenyl-N′-4-fluoro benzoyl thioureato) copper(II), (Cu(L5)2): Green. Yield: 86%. M.p.: 223-224°C. Anal. calcd. for C40H28CuF2N4O2S2, (%): C, 63.02; H, 3.70; N, 7.35. Found: C, 62.72; H, 3.68; N, 7.15. FT-IR (KBr pellet, cm−1): ν(Ar–CH) 3101, 3086, ν(CN) 1596, ν(C–O) 1498, ν(C–F) 698.

2.5. X-Ray Crystallography

The crystal structure of the synthesized four new compounds was solved by direct methods using SHELXS-97, and refinements were performed with SHELXL-97 [31]. Full-matrix least-squares refinement is based on F2. All nonhydrogen atoms were refined anisotropically. In three compounds, the hydrogen atom of N1 was found in difference Fourier map and refined isotropically. All other hydrogen atoms were positioned geometrically to their idealized positions, C–H = 0.93 (aromatic), 0.96 (CH3), and 0.97 (CH2) Å, and refined with a “riding model” with isotropic displacement parameters. Crystal data and details of the structural determinations for ligands (HL1, HL2, and HL4) and complex, Ni(L3)2, are given in Table 1.

tab1
Table 1: Crystal data and the structure refinement details for HL1, HL2, HL4, and Ni(L3)2.

3. Results and Discussion

3.1. Synthesis and Characterisation

4-Fluorobenzoyl isothiocyanate was produced by reaction of 4-fluorobenzoyl chloride with an equimolar amount of potassium thiocyanate in dry acetone. All benzoylthiourea derivatives (HL1–HL5) were synthesized from 4-fluorobenzoyl isothiocyanate and secondary amines in dry acetone. Scheme 2 outlines the synthesis of the series of thiourea derivatives. The ligands were purified by recrystallization from an ethanol : dichloromethane mixture (1 : 2) and obtained in yields ranging from 67 to 94%. 1H NMR spectra, FT-IR spectra, and elemental analysis data of all synthesized compounds confirm the proposed structures.

The reaction of the ligands with nickel acetate or copper acetate at room temperature with ethanol as solvent yielded the new complexes (ML2, M=Cu, or Ni). All the new metal complexes were recrystallized from ethanol : dichloromethane mixture (1 : 1). The proposed structures given in Scheme 1 are consistent with the analytical and spectroscopic data.

FT-IR spectra were taken with KBr pellets between 4000 and 400 cm−1. In the FT-IR spectra of the synthesized benzoylthiourea derivatives show sharp and strong absorption band at 3231, 3293, 3271, 3166, and 3159 cm−1 for HL1, HL2, HL3, HL4, and HL5 attributed to the stretching vibration of N–H group, respectively [11, 12, 21, 22, 2428].

The strong C=O stretching vibration band was observed in the range of 1643–1690 cm−1, which is in agreement with the literature data [11, 12, 21, 22, 2428]. In addition, synthesized compounds show weak intensity C=S stretching vibration in the 1251–1296 cm−1 range [11, 12, 21, 22, 2428].

All IR spectra of metallic complexes are practically similar. The N–H stretching vibration, present in the ligand around ~3200 cm−1, disappears in the complex spectra. At the same time, a new peak appeared in the range 1485–1500 cm−1, which was attributed to the absorption of C–O stretching vibration band. In the spectra of complexes, there is another intense absorption band at 1596–1602 cm−1 corresponding to the C–N fragment. All this conclusions are in agreement with the literature [11, 12, 21, 22, 2428].

The 1H NMR spectra of the ligands are consistent with their structures. The 1H NMR spectrum of ligands exhibited broad signals at 8.58, 8.41, 8.42, 8.14, and 8.64 for HL1, HL2, HL3, HL4, and HL5, respectively, due to NH protons. This peak does not appear in Ni(II) and Cu(II) complexes. These data are in agreement with the IR spectra and literature data [11, 12, 21, 23]. All other proton signals are appeared in appropriate place.

3.2. X-Ray Crystal Structures

We used X-ray single crystal diffraction method to determine and confirm the structure of the synthesized compounds. Only four of the synthesized compounds were suitable for X-ray single crystal diffraction. The molecular structures of HL1, HL2, HL4, and Ni(L3)2 are depicted in Figures 1, 2, 3, and 4, respectively. Selected bond lengths and angles are listed in Tables 2 and 3.

tab2
Table 2: Selected geometric parameters of (HL1, HL2, and HL4).
tab3
Table 3: Some selected geometrical parameters of compound Ni(L3)2.
536562.fig.001
Figure 1: Molecular structure of HL1. Anisotropic displacement ellipsoids are shown at the 50% probability level.
536562.fig.002
Figure 2: Molecular structure of HL2. Anisotropic displacement ellipsoids are shown at the 50% probability level.
536562.fig.003
Figure 3: Molecular structure of HL4. Anisotropic displacement ellipsoids are shown at the 50% probability level.
536562.fig.004
Figure 4: Molecular structure of Ni(L3)2. Anisotropic displacement ellipsoids are shown at the 50% probability level.

In each ligand, F atom is coplanar with the C1–C6 ring. The C2–C1–C7–O1 torsion angles set up by aromatic ring and the carbonyl group are 25.3(3), 5.0(3), and −20.3(4)°, for HL1, HL2, and HL4, respectively. The molecules of compounds HL1 and HL4 are effectively nonplanar, as shown by the values of the N1–C7–C1–C6 torsion angle, respectively, (Table 2); this angle defines the rotation of the aryl ring relative to the rest of the molecule. Within the thiourea moieties of compounds HL1, HL2, and HL4, the geometry at the carbon atoms is ideally planar, with a sum of the bond angles at C8 in HL1, HL2, and HL4 of 360.0(2), 360.0(2), and 359.9(2)°, respectively. The S1 atom is out of the plane of the N–C–N thiourea bridge by 0.051(1) Å in HL1, 0.029(1) Å in HL2, and 0.075(1) Å in compound HL4. The thiourea moiety is almost perpendicular to the phenyl ring plane with an angle of 80.9(1), 89.0(1) and 84.6(1)° for HL1, HL2, and HL4, respectively. In all ligands, the fluorobenzoyl ring and one of the methyl, ethyl, and n-butyl groups are trans to S1, but the other methyl, ethyl, and n-butyl groups are cis with respect to N2–C8 thiourea bond.

Bond distances and bond angles of the thiourea group agree well with those expected from other thiourea derivatives [22, 2830, 3234]. The C7–O1 and C8–S1 bonds both show typical double-bound character with bond lengths of 1.212(2) for HL1, 1.225(2) for HL2, and 1.219(3) for HL4 and 1.683(2) for HL1, 1.658(2) for HL2, and 1.673(3) Å for HL4, respectively. The C8–N2 and C7–N1 bonds also indicate a partial double bound character. These bonds due to their vicinity to the carbonyl group and methyl, ethyl, and n-butyl groups are slightly shorter in compound HL2 and HL4, but C7–N1 bond is almost the same as compared to the C8–N1 in compound HL1. The elongation of C8–N1 relative to C8–N2 and C7–N1 in compound HL2 and HL4 is in agreement with other thiourea derivatives [3, 32, 3539]. All the other bond lengths fall within the expected ranges [34]. The conformation of the molecule with respect to the thiocarbonyl and carbonyl moieties is twisted, as reflected by the torsion angles C8–N1–C7–O1 and C7–N1–C8–S1 of −1.6(3) and −127.0(2), −5.9(3) and 91.8(2), and −0.9(4) and 120.4(2)° for HL1, HL2, and HL4, respectively.

There are different kinds of interactions in the benzoyl thiourea compounds, but N–HS, C–HO, and N–HO intermolecular hydrogen bonds play a dominant role in the stabilities of crystal structures. The molecules of HL1, HL2, and HL4 are packed in a centrosymmetric manner through weak N–HS and C–HO hydrogen bonding. In compound HL1, crystal packing shows dimeric units formed through the N2–H2S1 and C2–H7O1 hydrogen bonds. The short C9–H9CS1, C10–H10AO1, and C10–H10CN2 distances of 2.50, 2.44, and 2.44 Å point out the presence of intramolecular hydrogen interactions. In compound HL2, crystal packing shows intermolecular N1–H1NO1 hydrogen bonds and molecules again form dimers. Intramolecular C9–H9AS1 hydrogen bonds are also similar to those in compound HL1. In compound HL4, the crystal packing shows intermolecular N1–H1NS1 and C2–H2O hydrogen bonds and molecules again form dimers. Intramolecular C–HO and C–HS hydrogen bonds are also similar to those in compounds HL1 and HL2. Hydrogen bonding and short contact geometry for three compounds HL1, HL2, and HL4 are given in Table 4.

tab4
Table 4: Hydrogen bonding geometry (Å, °) for HL1, HL2, HL4, and Ni(L3)2 compounds.

All of the structural data of the nickel complex agree with the elemental analysis, FT-IR spectroscopy, and 1H NMR spectroscopy data. Bis(N,N-dimethyl-N′-4-floro benzoyl thioureato) nickel(II) complex has a nearly square-planar coordination at the nickel atom. The distance of nickel atom from the best plane through the coordination sphere is 0.029 Å. The bond lengths of the carbonyl and thiocarbonyl groups lie between those for double and single bonds, a feature which is known from related structures (O1–C8: 1.271(8) Å; O2–C22: 1.271(7) Å; S1–C1: 1.729(7) Å; S2–C15: 1.745(7) Å) [11, 12, 21, 22, 40, 41] (Table 3). The bond length C1–N2 is 1.342(8) and N(2)–C(8) 1.340(8) Å. The bond length is C–N shorter than a normal single C–N bond. This is due to strong delocalization in the chelate rings [4244].

4. Conclusions

In this work, five flourobenzoyl thiourea ligands and their Ni(II) and Cu(II) complexes have been synthesized and characterized by elemental analysis, IR spectroscopy, and 1H NMR. Crystal and molecular structures of three synthesized ligands and one metal complex were analyzed by X-ray single crystal diffraction method. The comparative analysis was performed with literature data. The structure of these compounds is consistent with the structure of other thiourea derivatives. The bond lengths and angles also agree well with other thiourea derivatives. In the crystal structure, intermolecular N–HS, C–HO, and N–HO hydrogen bonds seem to be effective in the stabilization of the structure. In all ligands, molecules form dimers through strong intermolecular hydrogen bonds.

Disclosure

Crystallographic data (excluding structure factors) for the structures reported in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication number CCDC-811681 (HL1), CCDC-811682 (HL2), CCDC-811683 (HL4), and CCDC-865984 Ni(L3)2. Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.

Acknowledgments

This study is a part of Gun Binzet’s Ph.D. thesis and was supported by Mersin University Research Fund (Project no. BAP-FBE KB (GB) 2006-1 DR).

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