Kinetics and mechanistic studies of the interaction of thiosulfate with cis-diaqua-bis[1-alkyl-2-(arylazo)imidazole]ruthenium(II) complexes

This work describes the kinetics and mechanism of the interaction between sodium thiosulfate and cis-diaqua-bis[1-alkyl-2-(arylazo) imidazole]ruthenium(II) in acetonitrile-water (1:1) medium. The reaction proceeds in a two-step-consecutive manner. The product is characterized as Na2[Ru(RaaiR′)2(S2O3)2] by different spectroscopic techniques. The rate of the reaction is largely influenced by the π-acidity of the chelating ligand. Thermodynamic parameters are determined (Δ‡H0, Δ‡S0) from variable temperature kinetic studies, and these corroborate the rate data.