Spectroscopic and voltamperometric studies of Cu(II) complex with 3-amino-5,5-diphenylhydantoin
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2018-01-01
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Abstract
New copper(II)-aminohydantoin complexes ([CuAPh2Cl2(OH2)2]; [CuAPh2(NH3) (OH2)2], where APh is 3-amino-5,5-diphenylhydantoin), were synthesized and analyzed by means of elemental analysis, atomic absorption spectroscopy, UV-Vis spectroscopy and voltamperometric method. The complex forming processes in the Cu(II)- aminophenytoin (APh) system are studied by differential pulse polarography (DPP). The experiments are carried out at temperature of 20±1°C in ammonia buffer solution (pH = 8.2±0.1) at ionic strength I = 0.1. The reversibility of the reduction of the peak is proved and the equations of De Ford and Hume and these of Leden to DPP data are applied. The mean ligand number n of the complexes formed is found from the slopes of the straight lines of r ΔEpr = f(lgCAPh) function. The existence of two complexes (n =1 and 2) is proved in the presence of high ligand concentration (CAPh = 2.10-4 - 3.10-3 mol l-1) and the values of its conditional and total stability constants are found. It was found that the values of the total constants are lg CuβAPh = 8.0, lgβCuAPh2 =10.9 (I = 0.1). A satisfactory good coincidence between the results obtained by the procedure proposed and the literature data is observed. The atomic absorption spectroscopy and elemental analysis confirm the compounds stoichiometry. The IR and UV/Vis spectra show that APh act as bidentate ligands with the coordination involving the carbonyl oxygen and the nitrogen atom of amino group.