Chelating tendencies of N,N′-bis(2-hydroxyphenyl)ethylenediamine-N,N′-diacetic acid

Publisher Website
Google Scholar
Abstract
The proton association and metal complex formation constants of N,N′-bis(2-hydroxyphenyl)ethylenediamine-N,N′-diacetic acid (H4 hedda) have been determined utilising potentiometric and spectrophotometric techniques. The ligand is highly selective for the trivalent metal ion FeIII, the formation constant for the FeIII–H4hedda complex [log KFeL= 40.1 at 25 °C and I= 0.10 mol dm–3(KNO3)] being one of the highest reported so far for any 1 : 1 complex involving a multidentate ligand. Binding to the divalent metal ions MgII, CaII, MnII, CoII, NiII, CuII, ZnII, CdII and PbII, and to the trivalent metal ion LuIII, takes place in a stepwise manner, and the order in which the ligand donor groups become co-ordinated to the metal ions has been deduced.