Complexation of [S,S] and mixed stereoisomers of N,N′-ethylenediaminedisuccinic acid (EDDS) with Fe( iii ), Cu( ii ), Zn( ii ) and Mn( ii ) ions in aqueous solution

The protonation and complex formation equilibria of N,N′-ethylenediaminedisuccinic acid (EDDS) in the isomeric form [S,S] and a mixture of EDDS isomers (25% [S,S], 50% [R,S], 25% [R,R]) with Fe(III), Cu(II), Zn(II) and Mn(II) have been studied in aqueous 0.1 M NaCl solution at 25 °C by potentiometric titrations. The calculations were carried out with the computer program SUPERQUAD.