Synthetic -Peroxo Diiron Complexes

Synthetic diiron(III) peroxide complexes all exhibit electronic spectral features in the region of 500-600 nm associated with peroxide-to-Fe(III) charge-transfer transitions (Table VI). In the cases studied, resonance enhanced v(O-O) features are observed near (860 30) cm". These complexes are presumably p.-l,2-peroxo-bridged species, but definitive isotopic... 

Costas et al. have reported spectroscopic evidence for an Fe Fe complex that can be considered a structural model for the putative Fe Fe (/x-0)2 core of methane monooxygenase intermediate The synthetic complex was prepared at —80 °C in CH2CI2 by decay of a mononuclear low-spin Fe peroxo precursor. The Mossbauer spectra showed that all iron in the sample is intermediate spin (5 = 1) Fe, but the data were compatible with either a mononuclear site or a weakly coupled ( J <5cm ) symmetric dimer. Combination of the Mossbauer technique with resonance Raman and EXAFS spectroscopies provided evidence for a bis-/x-oxo bridged diiron(IV) complex. The complex of Costas et al however, is not an electronic model for intermediate Q, as the latter contains high-spin Fe sites. 

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