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

Resonance Raman spectra are reported for the purple intermediate formed in the reactions of [Fe(II)(EDTA)]2− and [Fe(III)(EDTA)]− with O2− and H2O2, respectively, using several different excitation wavelengths. The spectra show only two resonance‐enhanced bands, at 472 and 824 cm−1. 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−1 band is assigned to the ν(FeN) mode and the 824 cm−1 band to ν(OO). The structure of the species is shown to be the peroxide ion complex [Fe(III)(EDTA)(O2)]−. The O22− → Fe3+ electronic charge‐transfer transition is assigned at 454 nm.