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Abstract The present work comprises a study of the kinetics and mechanism of formation and oxidation of binary and ternary chromium (III) complexes involving iminodiacetatochromium(III) and a-amino acids (DL-aspartic acid) by N-bromosuccinimide. 1- Chapter (I): Introduction. The introduction contains electron transfer, outer-sphere and inner-sphere mechanisms which have been discussed. The nature and properties of chromium (III) and its complexes have been briefly discussed. The nature, properties, chemical behavior and different species in aqueous solutions of N-bromosuccinimide have been reported. The literature concerning on the oxidation of organic and inorganic compound in aqueous solutions and in aqueous organic solvents by N-bromosuccinimide are mentioned. The nature and properties of a-amino acids and IDA and their metal complexes have been briefly discussed. 2- Chapter (II): Experimental. Comprises the chemicals, preparation of metal complexes, the experimental procedures and the technique for the kinetic studies and methods for the data determination. 3- Chapter (III): Results and discussion. Includes the layout of the results obtained and their discussions. The effect of various parameters on the rate of reaction has been discussed. This chapter contains three parts: Part(I): The kinetics of formation of [CrIII(IDA)2(H2O)2] in aqueous solutions have been studied. The rate of the reaction increases with the increasing of (complex concentration , IDA concentration, temperature). and decreases with the increasing of pH. The formation of this complex obeys the following rate law. D[CrIII (IDA)2(H2O)2] /dt = ka Kocs [CrIII (H2O)6 3+] tot [IDA] / 1+ Kocs [IDA] The enthalpy of activation ∆H* and entropy of activation ∆S* also were calculated, and we propos that electron transfer proceeds through an inner-sphere pathway by replacement of coordinated H2O in the complex species, by IDA. Part (II): The kinetics of oxidation of [CrIII(IDA)2(H2O)2] by N-bromosuccinimide in aqueous solutions have been studied. The rate of the reaction increases with the increasing of (complex concentration , NBS concentration, temperature). and decreases with the increasing of pH. The oxidation of this complex obeys the following rate law. d[CrVI]/dt = {(k1 K2 + k2 K1 K3 / [H+]) [NBS] [Complex] } The enthalpy of activation ∆H* and entropy of activation ∆S* also were calculated, and we propos that electron transfer proceeds through an inner-sphere pathway by replacement of coordinated H2O in the two complex species, by NBS. Part (III): The kinetics of oxidation of [CrIII(IDA)(Asp)(H2O)2] by N-bromosuccinimide in aqueous solutions have been studied. The rate of the reaction increases with the increasing of (complex concentration , NBS concentration, temperature). and decreases with the increasing of pH. The oxidation of this complex obeys the following rate law. d[CrVI]/dt = {(k1 K2 + k2 K1 K3 / [H+]) [NBS] [Complex] } The enthalpy of activation ∆H* and entropy of activation ∆S* also were calculated, and we propos that electron transfer proceeds through an inner-sphere pathway by replacement of coordinated H2O in the two complex species, by NBS. |