There is a question in my chemistry book:

Find oxidation state of platinum ion in the complex $\ce{[Pt(O2)(en)2Br]+}$.

My books says that there is peroxide, but I want to ask why it is peroxide? Can it be superoxide?

My answer was that oxidation state of platinum is $+3$, but the answer in the book given is $+4$ with explanation that $\ce{O2}$ here is peroxide. How can I get to know from the formula that $\ce{O2}$ is peroxide and not superoxide?

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    $\begingroup$ You don't know that from the formula alone. $\endgroup$ Commented Jan 19, 2019 at 23:38
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    $\begingroup$ Peroxide ligands are typically bridging ligands, I'd expect it to be a dinuclear complex at least. It would be interesting to find out whether this standalone complex exists at all; if not, the textbook's question doesn't make much sense. $\endgroup$
    – andselisk
    Commented Jan 19, 2019 at 23:41

1 Answer 1


Here the oxygen "molecule" in its complex with hemoglobin is rendered as a superoxide ligand. But remember, electrons are shared between the metal and the ligand; so there may be some latitude in how you can apportion them to determine "oxidation states".


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