Reaction of iron III with hydroxyaminoacids : N,N-dihydroxyethylglycineiron II

Abstract

The stoichiometry and equilibrium for the reaction of iron III with N,N-dihydroxyethylglycine in aqueous medium has been investigated. Iron III is shown to'form only a 1:1 complex with the ligand; previous reports of a 2:3 complex are demonstrated to be erroneous, and probably resulted from non-equilibrium titration measurements. Using a modified Bjerrum titration procedure, the equilibrium constant for. the formation of the 1:1 complex at 25° has been determined to be 3.8 × 10 −6 moles 2 litre 2 . Attempts to differentiate between alternative structures for the complex are inconsequential, because the complex exists only in aqueous medium, where the ligand hydroxyl groups exchange rapidly with solvent water.