Nitrosoruthenium nitrite-nitrate complexes in aqueous and nitric acid solutions as probed by 15N NMR
Aqueous and nitric acid solutions of Na2[Ru15NO(15NO2)4OH] in the concentration range \(c_{H^{15} NO_3 }\) = 0–3.3 mol/L have been studied by 15N NMR, dominating complex species have been identified, and the equilibrium constants for the nitrate ion incorporation into the inner coordination sphere of nitrosoruthenium have been estimated. The equilibration time for such equilibria is no more than 2 h at room temperature. In addition to the nitro complexes, isomeric nitritonitronitrosoruthenium compounds have been identified in solutions. In weak acidic solutions at \(c_{HNO_3 }\) 1.5 mol/L, the fractions of dinitro- and mononitronitrosoruthenium complexes are comparable. In strong nitric acid solutions (\(c_{H^{15} NO_3 }\) = 10 mol/L) kept for three years in contact with air, nitro complexes are absent, and mononitrato- and dinitratoaquanitrosoruthenium complexes are dominating.