Oxidation of hydrazine by halogeno-complexes of iridium(IV) in acidic perchlorate solutions

Abstract

The reactions between hydrazine and hexachloroiridate(IV), monoaquapentachloroiridate(IV), diaquatetra-chloroiridate(IV), and hexabromoiridate(IV) have been studied kinetically. In each case the rate shows a first-order dependence on the concentrations of both reactants, whilst hydrogen-ion concentration has an inverse effect. Surprisingly, reaction of [IrCl₆]^2– is accelerated by Cl^–. Nitrogen is produced in stoicheiometric amounts as a product, and no formation of ammonia could be detected. Evidence for di-imide, N₂H₂, as an intermediate has been obtained by trapping with an unsaturated dicarboxylic acid. An interpretation of the results of the reaction kinetics is advanced.