Structures of Fe(III) complexes with EDTA and EDDDA in aqueous solution by EXAFS and XANES

Abstract

The Fe K-edge X-ray absorption spectra of Fe(III) complexes with EDTA (ethylenediaminetetraacetic acid) and EDDDA (ethylenediamine-N,N-diacetic-N,N′-dipropionic acid) in weakly acidic or neutral aqueous solutions are measured. The spectra of powdered crystalline samples of these complexes are also measured as the reference materials. The comparisons of the XANES spectra, including their pre-edge peak, and the EXAFS Fourier transforms conclude that in aqueous solution a seven-coordinate structure is predominant for the Fe(III)-EDTA complex and a six-coordinate one for the Fe(III)-EDDDA complex. © 1990.