The Influence of Anions on the Polarographic Reduction of

The influence of halide and isothiocyanate ions of the reduction wave of aquopentamminecobalt(‡V) and aquopentamminechromium(‡V) ions at the dropping mercury electrode has been studied by the measurements of current-potential and current-time curves. The cobalt (‡V) complex ion gives a kinetic-controlled reduction wave at more positive potentials than that of the reduction of cobalt(‡V) to cobalt(‡U) in the presence of bromide, chloride, and isothiocyanate ions, but does not give in the presence of iodide ions. In the case of the chromium(‡V) complex ion, such a kinetic current is not observed in the presence of these anions. An interpretation of the phenomena is made from the point of the potential difference between the reduction of the complex ions and the oxidationrednction potential of the couple of mercury and mercurous halides.