keywords: Intermediate, ionic strength, kinetic, oxidant, oxidation, reductant, stoichiometry
The reaction between thiourea (TU) and tetrakis(2,2’-bipyridine)-μ-oxodiiron (III) complex ([Fe2(bpy)4O]4+) hereafter referred to as Fe2O4+ has been studied in aqueous acidic media at hydrogen ion concentration ([H+]) of 0.001 moldm-3, constant ionic strength of 0.3 moldm-3(NaCl), T= 27 ±1°C and atwave length of maximum absorption (λmax) of 520 nm. The stoichiometry of reaction shows that one mole of oxidant is consumed per mole of reductant. The reaction is first order with respect to oxidant and reductant respectively and is not hydrogen ion and ionic strength dependent. The reaction conforms to the rate law: −d dt [Fe2O4+] = k2[Fe2O4+][TU]. Added SO 2 4 and CH3COO– inhibited the rate of reaction. The absence of both kinetics and spectroscopic evidence of intermediate complex formation suggest that the reaction proceeds by the outer-sphere mechanistic pathway and a mechanism is proposed.
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