Механизм реакции и уравнение полярографической волны выделения водорода, катализируемогo восстановливающимся активным комплексом

A catalytically active complex of Co with nitrohydroxylaminate ion in the H evolution reaction has the composition [Co(N2O3)2(NH3)(H2O)]2-. A general reaction for the formation of Ni and Co nitrohydroxylamine complexes in aqueous NH3 medium was given. Only the protonated Co complex is catalytically active. Alteration of the height of the catalytic wave with the Hg reservoir height is determined by the diffusion of the catalytically active nitrohydroxylamine complex. The protonated form of the Ni-nitrohydroxylamine complex prevails over the nonprotonated form at pH ≃ 7. The mechanisms of electrochem. and chem. reactions taking place in the polarog. reduction in NH3 buffer with nitrohydroxylaminate are given. Reduction of Co takes place simultaneously with H evolution, [Co(NH3)6]2+ formation, and with formation of an intermediate complex in which Co is in its zero valence state. The charge transfer coefficient is 0.5 in the electroreduction reaction which agrees with the exptl. data on the kinetics of electrochem. H evolution.