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Ok so I'm confused about the mechanism for this process:

enter image description here

Now the idea here is that iron first becomes oxidised to Fe(III) by placing an electron in the antibonding orbital of dioxygen. This is followed by the addition of 2 electrons from an external source. This causes the splitting of the O-O bond resulting in the formation of a hydroxide ion. In addition, iron loses another electron to oxygen forming the Iron(IV) oxide species shown.

Now what I do Not understand is the overall charges on the species at the end. I feel as if the original O-Fe(III) bond was considered purely ionic hence the lack of a formal charge on oxygen, yet at the end it seems as if the O=Fe(IV) bond is covalent, otherwise there would be a negative 2 charge on oxygen!

Is there a switch between ionic and covalent formalisms in the middle of this process?

If anyone could help explain the charges with perhaps a curly arrow mechanism to indicate the numbers of electrons on each atom then that would be most appreciated!

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    $\begingroup$ Quick look into available articles made me think that the first stage is one-electron transfer forming superoxide anion. Since superoxide is extremely reactive, the further steps depend highly on environment, as it would react with first available candidate. $\endgroup$ – permeakra Sep 4 '15 at 9:03

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