# In what compounds does oxygen exhibit +½ oxidation state?

Theoretically it is said that the compound can show oxidation states in the interval $[n,n-8]$ where $n$ is the number of valence electrons.

Is there any compound in which oxygen shows +1/2 oxidation state. If so, then please provide an example.

• $\ce{O2+[PtF6]-}$ is an example. – Ivan Neretin Jul 10 '16 at 15:54
• And a famous one at that. Its synthesis heralded the similar synthesis with $\ce{Xe}$ in place of molecular oxygen, and thus the coming of noble-gas chemistry. – Oscar Lanzi Jul 16 '16 at 0:18
• The rule doesn't work with d-elements that good. FYI, Mn shows oxidation states -3 ... +7 afaik except -2 and for Iridium it's -3..+8 .... – permeakra Aug 9 '16 at 18:56

Yes. The dioxygenyl ion, $\ce{O_{2}^+}$, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of +1/2. It is formally derived from oxygen by the removal of an electron:
$$\ce{O_{2} → O_{2}^+ + e^{-}}$$