Kinetics and mechanism of the ligand substitution reaction of aquodiethylenetriaminepentaacetatoruthenate (III) in aqueous solution

The kinetics of ligand substitution reactions of [Ru(H2dtpa) (H2O)] (2) (H2dtpa=diprotonated diethylenetriaminepentaacetic acid) were studied as a function of ligand (L′) concentration, pH (2.5–8.0) and temperature (30–45 °C) at 0.2 M ionic strength. The equilibrium constants for the formation of mixed ligand complex [RuIII(dtpa) (L)] (L=2-mercaptopyrimidine, cysteine) and the distribution of various species in solution in the pH range of 2.5–8.0 were computed from potentiometric results.