Abstract
Electrochemical reduction of (methyl fumarato) pentamminecobalt (III) [Co00CCH = CHCOO-CH3 (NH3) 5]2+h and (hydrogenfumarato) pentamminecobalt (III) [COOOCCH = CHCOOH (NH3)5]2 ions has been studied by means of polarography and controlled potential coulometry. In acetate buffer solutions both ions respectively give two palarographic steps. It has been shown that the first steps correspond to the reduction of Co(III) to Co(II) and the second steps to the reduction of the respective organic ligands which are liberated at the electrode surface; consequently, no ester hydrolysis occurs in the course of the reduction of the methyl fumarato complex ion. The works of Taube and co-workers on the homogeneous reduction of the methyl fumarato complex ion have been reviewed. The contradictory results reported by these authors may be explained by the fact that the reaction between (hydrogenfumarato) pentamminecobalt (III) perchlorate and diazomethane does not give the corresponding methyl fumarato complex.
