New Platinum Superoxo Complex. Kiselev Yu.M., Pankratov D.A., Shundrin L.A., Kiseleva I.N. //Russian Journal of Inorganic Chemistry. 1996. V. 41. № 12. P. 1963-1966
Products of oxidation of Pt(IV) hexahydroxo complexes with ozone in alkali media have been studied with physicochemical methods (electron spectroscopy, EPR, and cyclic voltammetry). The oxidation product is pink at alkali concentration in solution higher than 5 mol/l. The pink complex represents previously undescribed platinum superoxo complex with a bridging O2- group.
Our previous study concerned the possibility of preparing platinum compounds in unusually high oxidation states from alka1ine solutions under the action of ozone. In that study, we detected a blue platinum superoxo complex of binuclear structure with the O2- bridging group. The bridge structure of this complex was supported by ESR, and the complex was show to form only at rather low alkalinity. At higher alkali concentrations (cOH- > 5 mol/l), a similar reaction results in a pale pink complex containing oxidizer.
Platinum(IV) Superoxo Complexes. Kiselev Yu.M., Pankratov D.A., Ezerskaya N.A., Kiseleva I.N., Shundrin L.A., Popovich M.P. //Russian Journal of Inorganic Chemistry. 1994. V.39. №8. P. 1278-1283
The products of reaction of platinum(IV) hydroxo complexes with ozone in alkaline solutions were studied using various physicochemical methods: electronic spectroscopy, electron spin resonance, and cyclic voltammetry. The arguments presented suggest that the blue solutions obtained contain superoxo Pt(IV) complexes.
One of the most efficient ways to stabilize higher oxidation states in the transition elements is complex formation in aqueous-alkaline media. In this case, hydroxyl ions offer advantages over other ligands and produce a stronger decrease in E° of a redox system than other, rather weakly polarizable ligands, which form complex ions in acid and neutral media. This circum stance is the one favoring stabilization of the highest oxidation states in neptunium, plutonium, americium(VII), and iron(VIII).