Does the carbon dioxide dianion exist?

I have heard that the dianion of carbon dioxide, $\ce{CO2^{2-}}$ was named carbonite.


Does such a species really exist? Basically, is it stable enough to be a plausible molecule? If so, under what conditions is this true?


This question is very confusing to me, I understand the concept somewhat but I don't know what information I need in order to figure out the answer.




The obvious *Star Wars* puns aside, I have never heard about the dianion of a carbon dioxide **dianion** and/or that it was named carbonite.


However, the carbon dioxide radical anion, $\ce{CO2^{.-}}$, is experimentally available.


Typically, it is generated by hydrogen atom abstraction from formate, $\ce{HCOO-}$, using $\ce{HO^.}$ radicals. The $\ce{HO^.}$ radicals, in turn, are obtained from vacuum ultraviolet (VUV) irradiation of water at a wavelength of $\lambda = 175~\mathrm{nm}$.




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**UPDATE**


Apparently, I was **wrong** about the dianion! As *Mithoron* pointed out in his comment, species like $\ce{(M^+)\_2CO2^{2-}}$, formed in the reaction carbon dioxide with alkali metals in argon or nitrogen matrixes, have been detected by IR spectroscopy. See [*Inorganic Chemistry*, **1984**, *23*, 177-184](http://dx.doi.org/10.1021/ic00170a013) for details.


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