Premium
Mössbauer Investigation of Peroxo Species in the Iron( III )–EDTA–H 2 O 2 System
Author(s) -
Sharma Virender K.,
Szilágyi Petra Á.,
Homonnay Zoltán,
Kuzmann Ernő,
Vértes Attila
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500299
Subject(s) - chemistry , adduct , mössbauer spectroscopy , decomposition , ligand (biochemistry) , medicinal chemistry , chelation , inorganic chemistry , nuclear chemistry , crystallography , organic chemistry , biochemistry , receptor
The reaction of a diiron( III )–EDTA complex with H 2 O 2 in alkaline medium is studied by Mössbauer spectroscopy in conjunction with the rapid‐freeze/quench technique in order to identify possible intermediate species during the formation and decomposition of the purple (EDTA)Fe III (η 2 ‐O 2 ) 3– complex ion. Starting from the six‐coordinate [Fe III EDTA] – species at acidic pH, it is demonstrated that mononuclear complexes formed at a pH of about 1 are convert into the diiron( III )–EDTA complex [(EDTA)Fe III ‐O‐Fe III (EDTA)] 4– upon raising the pH to around 10.4. H 2 O 2 reacts with the diiron( III ) complex to give peroxide/hydroperoxide related adducts. Initially, the reaction tears apart the dimers to form a peroxo adduct, namely the seven‐coordinate mononuclear [(EDTA)Fe III (η 2 ‐O 2 )] 3– , which is stable only at very high pH. The decomposition of this peroxo adduct gives two new species, which are reported for the first time. The Mössbauer parameters of these species suggest a six‐coordinate μ‐peroxodiiron( III ) complex [(EDTA)Fe III ‐(OO)‐Fe III (EDTA)] 4– and a seven‐coordinate μ‐hydroxo‐μ‐peroxodiiron( III ) complex [(EDTA)Fe III ‐(OO)(OH)‐Fe III (EDTA)] 5– . A badly resolved, extremely broad component is observed in the Mössbauer spectra during the conversion of the monomer to dimeric peroxo species, which may be attributed to the short‐lived [(EDTA)Fe III ‐OO] 3– or [(EDTA)Fe III ‐OOH] 2– intermediate species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)