POLAROGRAPHIC REDUCTION OF HEXAMMINECOBALT (III) ION. THE EFFECT OF COMPLEXING AGENTS
ILLINOIS UNIV AT THE MEDICAL CENTER CHICAGO COLL OF DENTISTRY
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Studies were made of the effect of varying NH sub 3 concentration upon the polarographic reduction of CoNH sub 3 sub 6 3. Potentiometric measurements indicated that the first step of the process was an electron transfer to form CoNH sub 3 sub 6 2. The irreversibility of the process was attributed to the slow transformation of the divalent ion from the inital d squared and sp cubed hybridization structure to the stable sp cubed d squared structure. The oxidation of CoNH sub 3 sub 6 2 was studied by using a rotating Pt electrode. The anodic current due to the oxidation at the electrode was about 1 of the diffusion-controlled value and was limited by the rate of the reverse transformation. The reduction of CoNH sub 3 sub 6 3 in the presence of 0.1M ethylenediamine occurred at a potential of about -0.250 v., and the product rapidly came into equilibrium with the complexing agent. The divalent ethylenediamine complex is oxidized as long as the potential is more positive than that required for the reduction of trisethylenediamine-cobalt III, resulting in a net current of zero. Results are also presented of studies of the reduction of CoNH sub 3 sub 6 3 in concentrated chloride and hydroxide solutions.
- Atomic and Molecular Physics and Spectroscopy