Induced reactions involving tin III intermediate

The formation of tin(III) intermediate during the oxidation of tin(II) has been postulated earlier in some cases, although direct evidence has not been quoted. Recently a couple of cobalt(III) complexes were supposed by Higginson et u/. to demonstrate the presence of tin(III). 

The method proposed is appropriate to show the presence of a strongly reducing intermediate. However, it is usually not possible to identify this entity as tin(III) merely on the evidence of the consumption of cobalt(III) complex present. To this end additional (kinetic) evidence is necessary. Nevertheless, the investigation of the induced reduction of cobalt(III) complexes is useful as a simple means of deciding whether the oxidation of tin(II) involves 1- or 2-equivalent steps. 

The mechanism of this reaction adopted by earlier investigators was 

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