Equilibria and kinetics in aqueous solutions of hydroxyethylethylenediaminetriacetatocobalt(III)

Abstract

A previous suggestion that sexidentate as well as quinquedentate complexes of hydroxyethylethylenediaminetriacetic acid are formed with cobalt(III) has been confirmed. Both forms exist as conjugate acid–base pairs, and the equilibrium and kinetic behaviour of the system can be described in terms of the two corresponding acid dissociation constants together with four first-order velocity constants, each of which relates to the disappearance of one of the four forms. The earlier evidence in favour of geometrical isomers of these complexes is shown to be false.