Resonance Raman studies of transition metal peroxo complexes: 2‐The purple intermediate formed in the reactions of iron(II) and iron (III)ethylenediaminetetraacetate with superoxide and hydrogen peroxide, respectively

Abstract

Resonance Raman spectra are reported for the purple intermediate formed in the reactions of [Fe(II)(EDTA)]'-and [Fe(III)(EDTA)]-with 0, and HzOz, respectively, using several different excitation wavelengths. The spectra show only two resonance-enhanced bands, at 472 and 824 cm-'. The band intensity excitation profiles for these two are different, demonstrating that the resonance effects observed are associated with two different electronic transitions. The 472 cm-' band is assigned to the v(Fe-N) mode and the 824 cm-' band to v(0-0). The structure of the species is shown to be the peroxide ion complex [Fe(III)(EDTA)(02)]-. The Oz-+ Fe3+ electronic charge-transfer transition is assigned at 454 nm.

Detailed Spectroscopic, Thermodynamic, and Kinetic Studies on the Protolytic Equilibria of FeIIIcydta and the Activation of Hydrogen Peroxide

“…Presumably, this reaction involves an intramolecular rearrangement to the [Fe III (cydta)(η 2 -O 2 )] 3− peroxo complex, which is catalyzed by OOH − at pH values around the p K a value of hydrogen peroxide. For Fe(edta), the [Fe III (edta)(η 2 -O 2 )] 3− peroxo complex has been well characterized. − …”

“…These nonheme iron peroxo intermediates have been characterized by various techniques. , One well-characterized peroxo species is the purple complex [Fe III (edta)(η 2 -O 2 )] 3− , formed upon the addition of hydrogen peroxide to [Fe III (edta)(H 2 O)] − . This reaction was first studied in 1956 and was found to catalyze the oxidation of organic substrates, the polymerization of styrene, and the decomposition of H 2 O 2 . , The [Fe III (edta)(η 2 -O 2 )] 3− complex was proven to be a high-spin Fe III side-on peroxo complex by a variety of techniques such as Raman spectroscopy, − Mössbauer spectroscopy, , low-temperature absorption spectroscopy, variable-temperature and variable-magnetic-field circular dichroism, and paramagnetic resonance spectroscopy. , In addition, kinetic information on the activation of H 2 O 2 by Fe III edta is available. ,− …”

Geometric and Electronic Structure/Function Correlations in Non-Heme Iron Enzymes

“…a. Side-On Peroxo Complexes. As mentioned above, the purple Fe III −EDTA peroxide system was probably the first non-heme iron oxygen intermediate discovered and remains one of the most intensely studied. ,,,,,− Since the spectral features of the 1:1 adduct between Fe III EDTA and H 2 O 2 at elevated pH (>10) are now reasonably well understood, it provides an important reference for a mononuclear non-heme ferric peroxide complex with a side-on (η 2 ) peroxide binding mode …”

Real‐time Raman analysis of cleaning solution: Determination of Al/Alq3 residue in cleaning mixture

“…The EDTA‐K 4 component in TFD4 does not participate in the reaction when aluminum is added. In reference , it showed the appearance of a new vibration in the spectrum of EDTA‐Na‐Ti‐O compared with that of the conventional EDTA solution, and the existing peaks were also affected . This is because the crystallinity of TiO 2 activates the Raman‐forbidden modes by relaxing the phonon selection rules .…”