
%0 Journal Article
%A Bayston, JH 
%A Beale, RN 
%A King, NK 
%A Winfield, ME 
%T Reaction of the Pentacyanocobaltate(II) Ion with Molecular Oxygen
%J Australian Journal of Chemistry
%D 1963/12/01
%V 16
%N 6
%P 954-968
%K 
%R https://doi.org/10.1071/CH9630954
%U https://www.publish.csiro.au/paper/CH9630954 
%X By spectrophotometric scanning of reacting solutions, we have studied the processes which can occur when Oz is admitted to aqueous solutions containing the Ion [CoII(CN)5]3- in the concentration range 0.0002-0.4M, at 0°. A scheme is given to explain the formation of and inter-relations between [(CN)5CoIII-O-O-CoIII(CN)5]6-; [(CN)5CoIII-O-O-CoIV(CN)5]5-; [(CN)5CoIIIOH2]2- ; [CoIII(CN)6]3-, and a complex believed to be [(CN)5CoIII-O-OH]3-, which absorbs at 272 mp Preparative methods are described for obtaining several of the oxidation products in the crystaline state.   Hydrolysis of [(CN)5CoIII-O-O-CoIII(CN)5]6- to [(CN)5CoIIIOH2]2- takes place via the 272 m&#956; complex, which is fairly stable in alkaline solution and is resistant to oxidation. The same 272 m&#956; complex can be formed more directly by oxygenation of the hydrido complex [(CN)5CoIIIH]3-, which is present in aged or hydrogenated solutions of pentacyanocobaltate(II).   All of the pentacyano oxidation products can be reduced by sodium borohydride to [(CN)5CoIIIH]3-, which is further reduced by excess borohydride to an insoluble green compound and finally to metallic cobalt.   We have briefly examined the reactions of ammonia and CN- with [(CN)5CoIIIOH2]2-, and the reaction of [(CN)5CoIII-O-O-CoIV(CN)5]5- with reducing agents, including [CoII(CN)5]3-. 
