Molten sodium nitrite-sodium nitrate-potassium nitrate eutectic: The reactions and spectra of iron(III), cobalt(II), nickel(II) and copper(II) compounds

Article abstract of DOI:10.1016/S0040-6031(96)02960-7

In the sodium nitrite sodium nitrate-potassium nitrate ternary eutectic, iron(III), cobalt(II) and nickel(II) chlorides were found to undergo Lux Flood acid base reactions to form their most stable oxides, which were insoluble, while copper(II) sulphate reacted to form a basic nitrate. The stoichiometry of the reactions in the presence of the competing basic anions was much more similar to those found in pure nitrite than in pure nitrate melts, but the oxidation of nitrite to nitrate, possibly via nitric oxide and nitrogen dioxide, was shown to be important. The green solution of nickel(II) chloride had a spectrum which was much more similar to that in pure nitrite than in pure nitrate melts. Octahedral coordination by nitro, nitrito and nitrato ligands is suggested, in the ratio 2:1:3.