Trioxalatokobaltat(III)‐Ion in wässeriger Lösung: Thermischer Zerfall und Elektronaustausch mit Dioxalatokobaltat(II)‐Ion

Abstract

AbstractThe thermal decomposition of CoOx has been investigated in neutral and acid solutions and in presence of the metal ions Li+, Mg2+, Cd2+, Be+2, Mn2+, Co2+, Zn2+, Ni2+, Cr3+, Al3+, Cu2+, Fe3+. Their catalytic influence increases in the series as listed, without being connected with appreciable changes in the activation energy which is also the same for decomposition in neutral and acid solution. In the electron exchange reaction between oxalate complexes of CoII and CoOx, the complex CoOx i the only important species. The activation energy is slightly lower for the electron exchange than for the thermal decomposition. The exchange is catalysed by Cerium (III + IV). Mechanisms are postulated which connect all the reactions studied as well as the isomerization of CoOx in aqueous solution, suggesting that the latter process has to be considered as a reversible oxidation of the ligand by CoIII. Several independent facts suggest that the free radical ion C2O does not appear as an unstable intermediate in solution. The transition state of the exchange reaction is likely to involve a bridged binuclear species. All reactions described are intimately connected with the entrance of water into the first coordination shell of CoOx.