Ferryl species calculations

Fenton chemistry (320-322) and indicates that ferryl species (at least when supported by bispidine ligands) rather than OH radicals may be involved in substrate oxidation. For iron(II) aqua ions, this has also been proposed on the basis of DFT calculations (323), and a similar mechanism is confirmed by DFT calculations with the bispidine complexes (174). 

Homer O, Oddou JL et al (2006) Mossbauer Identification of a protonated ferryl species in catalase from Proteus mirabilis density functional calculations on related models. J Inorg Biochem 100 477-479... 

DFT calculations suggest that the doublet-and quartet-spin states of the P450 compound I ferryl porphyrin radical cation are energetically close. According to these calculations, both the doublet and quartet species oxidize ethylene by addition of the ferryl oxygen to one carbon, leaving an unpaired electron on the second carbon of the double bond (Fig. 4.30) [185]. This intermediate radical also exists in doublet and quartet... 

Compound I can oxidize a chloride anion and has been proposed to form an Fe(III)-hypohalite intermediate [27]. However, it has not yet been entirely resolved whether this hypohalite intermediate directly chlorinates the organic substrate [28], or whether HOCl is released upon protonation of the intermediate and free HOCl or CI2 performs the chlorination reactions [29]. Interestingly, it has been shown by extended X-ray absorption fine structure (EXAFS) spectroscopy that the ferryl form is consistent with a protonated 0x0 species, which agrees well with density functional calculations on an Fe(IV)-OH species [30]. 

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