The Reactivity of the Pentacyano(η1‐Dioxygen)cobaltate(III) Ion in Aqueous Solution

The mononuclear η1‐dioxygen complex [Co(CN)5O2]3− (A) decomposes in aqueous solution to the hydroxo‐complex [Co(CN)5OH]3− (B) and the hydroperoxo complex [Co(CN)5CoO2N]3 (C). The mechanism involves partial dissociation of A to give [Co(CN)5]3− (E) which binds with unreacted A to give the η1:η1‐peroxo complex [(CN)5Co02Co(CN)5]6− (F) which is hydrolysed to B and C. The mechanism is supported by the effects of pH, dioxygen concentration, and ionic strength on the rate of decomposition, and by the trapping of oxidation products of E and F. Complex A reacts readily with reducing agents to give directly the hydroperoxo complex C.