Inner Sphere Reduction of Tris(pyridine-2- carboxylato)manganese(III) by Hydroxylammonium Ion in Sodium Picolinate-Picolinic Acid Buffer Media

Abstract

Abstract The kinetics and mechanism of the oxidation of hydroxylamine by tris(pyridine-2-carboxylato)manganese( III) in Na(pic)-picH [where Na( pic) = sodium salt of pyridine-2-carboxylic acid (picH)] has been studied in the pH range 4.89-6.10. The rate of the reaction increases with increasing [substrate] but with decreasing acidity. A rate expression has been derived from which the dissociation constant of the equilibrium NH3OH+ ⇄ NH2OH + H+ has been computed at different temperatures. Activation parameters for the slow rate determining step have been evaluated. Manganese(III) complex is reduced by the hydroxylammonium ion by an inner sphere mechanism. The reaction appears to proceed through the intermediate formation of free radicals to give products of oxidation.