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 25degreesC by potentiometric titrations. The calculations were carried out with the computer program SUPERQUAD.