Physicochemical properties of solutions of bis(2,3,5,6-tetraoxo-4- nitropyridinate) dianions. Crystal structures of sodium 2,3,5,6-tetraoxo-4- nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4- nitropyridinate) monohydrate

Ammonium 2,3,5,6-tetraoxo-4-nitropyridinate was shown to exist as stable dimers and act as a weak electrolyte in both a crystalline state and aqueous solutions. In a strongly alkaline medium, ammonium cations were successively replaced by sodium cations. The molecular and crystal structures of sodium 2,3,5,6-tetraoxo-4-nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4-nitropyridinate) monohydrate were established, and their spectroscopic characteristics were determined. © 2004 MAIK "Nauka/Interperiodica".