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

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

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-(4fluorobenzoyl) thiourea compounds (alkyl: methyl (HL 1 ), ethyl (HL 2 ), n-propyl (HL 3 ), n-butyl (HL 4 ), and phenyl (HL 5 )) which include a fluorine atom and their Ni(II) and Cu(II) complexes (Scheme 1).The crystal and molecular structures of HL 1 , HL 2 , HL 4 , and Ni(L 3 ) 2 were characterized by single crystal X-ray diffraction.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 1 H NMR spectrums were recorded in CDCl 3 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, MoK  ( = 0.71073 Å) radiation.

2.2.
Reagents.4-Fluorobenzoyl chloride, potassium thiocyanate, dimethylamine, diethylamine, di-n-propylamine, di-nbutylamine, 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.

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.

General Procedure for the Synthesis of Metal Complexes.
The metal complexes were prepared according to a described method [21][22][23].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).
Scheme 2: Synthesis of the ligands.

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 F 2 .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 (CH 3 ), and 0.97 (CH 2 ) Å, and refined with a "riding model" with isotropic displacement parameters.Crystal data and details of the structural determinations for ligands (HL 1 , HL 2 , and HL 4 ) and complex, Ni(L 3 ) 2 , are given in Table 1.  with an equimolar amount of potassium thiocyanate in dry acetone.All benzoylthiourea derivatives (HL 1 -HL 5 ) 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%. 1 H NMR spectra, FT-IR spectra, and elemental analysis data of all synthesized compounds confirm the proposed structures.

Results and Discussion
The reaction of the ligands with nickel acetate or copper acetate at room temperature with ethanol as solvent yielded the new complexes (ML 2 , 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.
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,[24][25][26][27][28].
The 1 H NMR spectra of the ligands are consistent with their structures.The 1 H NMR spectrum of ligands exhibited broad signals at 8.58, 8.41, 8.42, 8.14, and 8.64 for HL 1 , HL 2 , HL 3 , HL 4 , and HL 5 , 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.

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 HL 1 , HL 2 , HL 4 , and Ni(L 3 ) 2 are depicted in Figures 1, 2, 3, and 4, respectively.Selected bond lengths and angles are listed in Tables 2 and 3.

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 1 H 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-H⋅ ⋅ ⋅ S, C-H⋅ ⋅ ⋅ O, and N-H⋅ ⋅ ⋅ O hydrogen bonds seem to be effective in the stabilization of the structure.In all ligands, molecules form dimers through strong intermolecular hydrogen bonds.
Copies of the data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.

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.

Scheme 3 :
Scheme 3: Synthesis of the metal complexes.

Figure 1 :
Figure 1: Molecular structure of HL 1 .Anisotropic displacement ellipsoids are shown at the 50% probability level.

Figure 2 :Figure 3 :
Figure 2: Molecular structure of HL 2 .Anisotropic displacement ellipsoids are shown at the 50% probability level.