Synthesis and Characterization of some Transition Metals Complexes with new Ligand Azo Imidazole Derivative

AZO complexes synthesized by binding metal ions as Mn(II), Co(II), Ni(II) and Cu(II), with the ligand (L) [ethyl 4-((E)-(5-oxo-1-(((1E,2E)-3-phenylallylidene)amino)-2-thioxo-2,5-dihydro-1H-imidazol-4-yl)diazenyl)benzoate] was prepared from three steps ,first step preparation Schiff base product of condensation reaction by reaction Thiosemicarbazide with cinnamaldeyde, second step preparation the Imidazole ring close by reaction ligand 1 with chloroethylacetate, finally preparation Azo ligand(Diazanium compound) by reaction ligand 2 with benzocain. Characterized the ligands and complexes in their solid state using the elemental micro analysis (C.H.N.S), flame atomic absorption. UV-vis spectroscopy, FT-IR, magnetic susceptibility measurements, Mass spectrum, 1H-NMR spectra and electrical molar conductivity. These techniques produced comparable results with those obtained for the solid complexes. From the data of all techniques, octahedral geometry was proposed for Mn(II), Co(II), Ni(II) and Cu(II)


INTRODUCTION
Condensation reactions involving primary amines and ketones or aldehydes produced under particular circumstances produce Schiff bases. The Schiff bases is one of the most important organic compound and more interesting by the researchers due to contain (-C=N-)group [1]. The imidazole ring, which may be found in a range of natural products and pharmaceuticals, is one of the most frequent five-membered, nitrogen-containing heterocyclic scaffolds. Furthermore, imidazole-based heterocyclic compounds [2], play a crucial role in biochemistry, have been playing a key role in the treatment of a different of illnesses, and innovative pharmaceutical derivatives are being developed with encouragement all over the world [3][4]. Because of the peculiar structural characteristic of imidazole scaffold with a beneficial electron-rich property showing a wide variety of biological activities, it is desired for imidazole groups to bind with diverse receptors and enzymes in biological systems through various weak interactions. An imidazolecontaining medications have been widely used to 32 treat a range of diseases, including antibiotic infections, in recent years. [5][6], antifungal [7][8], anti-inflammatory [9][10], antiviral [11][12], anti-parasitic [13][14], anticancer [10][11][12][13][14][15], antihistamine [16][17]and enzyme inhibition [15][16][17][18]. As demonstrated in Table 1, Imidazole and its derivatives are employed in a variety of medical applications. Many Azo Imidazole derivatives, thiosemicarbazone ligand molecules, and their complexes have been widely employed and applied in biological, analytical, and pharmacological activities. Many Azo Imidazole compounds and their significant heterocyclic complexes have been studied for their antibacterial, antifungal, antiinflammatory, and analgesic properties. [10]. These compounds variously used in the spectrophotometric measurement of metal ions. As a result, several of those reagents produce vibrant colors when they react with transition metal ions. [19] delivering probes that can also coordinate with rare earth ions, creating metal complexes with unique geometries [20]. In the present paper, the preparation of Imidazole derivative [ethyl 4-((E)-(5-oxo-1-(((1E,2E)-3-phenylallyli dene)amino)-2-thioxo-2,5-dihydro-1H-imidazol -4-yl)diazenyl)benzoate] (L) was used as a ligand that provides two sites "potential donor" to produce some transition metal ions. (L) ligand and its complexes were completely characterized. We study Synthesis and Characterization of some Transition Metals Complexes with new ligand Azo imidazole derivative.

MATERIALS AND METHOD
All the used chemicals were analytical annular and were highly pure.

The Physical Measurements and Analysis
The melting points were measured using Gallen Kamp melting point instrument and were uncorrected. While, FT-IR spectrum was measured using Bruker spectrophotometer at the range (4000-400 cm -1 ). UV-vis. spectrum recorded on (Shimadzu1900) spectrophotometer at room temperature. A 500 MHz Agilent Technologies spectrometer was used to record 1 H NMR spectra in DMSO-d6, using a tetramethylsilane (TMS) as an internal standard. Furthermore, all these measurements collected at a concentration of 10 -3 M of the complex in absolute ethanol as a solvent. The elemental (C.H.N.S) analysis was performed using an Eager 300 for EA1112 analyzer. The atomic absorption of the prepared complexes was measured using "Shimadzu Atomic Absorption 680 Flame" spectrophotometer. The mass spectrum of the ligand was obtained on an Electron-Impact (EI) mass spectroscopy. The mass spectrum of the metal complexes was obtained on an MSDCHEM.The conductivity measurements recorded on Philips pw-Digital Conductometer. All these measurements recorded in "DMSO" as a solvent using the concentration of (10 -3 M) at 25 o C. The measurements of magnetic susceptibility collected at 25 o C in solid state using Faraday's method at "Bruker BM6" instrument.

Steps of preparation azo compound (L)
Step 1: Synthesis of Schiff base ligand 1 the solution of Thiosemicarbazide (1mmole) in Ethanol as a solvent (25 mL), (E)-3-phenylprop-2-enal (1mmole) was added with two drops of glacial acetic acid was added drop by drop at room temperature with constant stirring. After heating the mixture was refluxed for 8h, the mixture was poured onto ice water. It was filtered off, washed with ethanol and diethyl ether then dried to give compound 1. The yield of yellow product was (85 % ), and the melting point was equal to (97-100 o C) [21].
Step 2: Synthesis of Imidazole ligand 2 A mixture of compound 1 (1mmol) and ethyl chloroacetate (1mmol) was heated under reflux for 8 hours in ethanol solution (30 mL) containing anhydrous sodium acetate (1mmol). To get the product compound 2, the reaction mixture was cooled, and the resultant precipitate was filtered out and recrystallized from ethanol. The yield of yellow product was (85%), and the melting point was equal to (92-94 °C) [22].

Characterization of ligand (L) along its complexes achieved by
A) The Elemental Micro Analysis physical and analytical data of ligand (L) and its metal complexes are shown in Table 2. These data are; consistent with the calculated values. The suggested molecular formula also supported by the subsequent spectra and the magnetic moment.

B) 1 H-NMR Spectra
In Figure 1, H-NMR spectrum of AZO compound (L), in DMSO-d6 showed peak at 1.35 ppm which could be related to Methyl groups that appeared at range 1.26-2.5 ppm [24].

E) Studying of Electronic Spectra, Magnetic Moment, Conductance
In Figures 6 and 7, the UV spectrum of ligand (L) mostly shows three intense absorption peaks at 37543 cm -1 , 34482 cm -1 and 33456 cm -1 which belong to π→π*, and n→π* and C.T, respectively, (See Table 4 [13], (See Table 4, Figure 5) for an octahedral geometry [28]. Moreover, the magnetic moment µeff. of this complex in the sold state (4.50 B.M) suggests a low-spin octahedral geometry [29]. Furthermore, measuring the conductivity in (DMSO) demonstrated that this complex has a no conductivity showed that this complex is [1:1] metal to ligand; Scheme3.

Suggested Structure for Complexes (1-4)
According to the obtained results from the elemental and spectral analyses, besides measuring the magnetic moment and conductivity, the mentioned above compounds suggested structures can be explained as shown in Scheme 4.

ACKNOWLEDGEMENT
Authors are so grateful for the members of chemistry department, College of science, Mustansiriyah University for facilities of FT-IR, UV-Visible spectra and magnetic moments measurements and special thanks to Dr.Ahmed H. Ismail Head of Chemistry department and chemists in laboratories above.