Thermodynamic and kinetic studies on the interaction of RuIII(edta) with NO in an ionic liquid

The aim of this study was to determine rate constants for the release of NO from an iron(II) nitrosyl complex dissolved in a typical imidazolium-based ionic liquid, [emim][dca], using an NO trapping technique combined with stopped-flow measurements. The anionic component of the selected ionic liquid, viz. [dca] (dicyanamide), was found to coordinate to the Ru-III(edta) complex used as trapping agent, and hindered its successful application. Further investigations in aqueous solution revealed thermodynamic and kinetic data for the formation of the [Ru-III(edta)(dca)](2-) complex and its reaction with NO to form the corresponding nitrosyl complex. The results obtained under conditions similar to those in the ionic liquid indicated a much slower formation of the nitrosyl complex in [emim][dca] compared to that reported for the formation of this complex in aqueous medium.