What are the properties of COₓ where x ≥ 3? $\ce{CO_x}$ are part of the oxocarbon molecule class. Commonly known are $\ce{CO}$ and $\ce{CO2}.$ However, there are molecules in which $x$ is equal to or larger than $3.$ Those molecules are barely known, other than the fact that they're unstable. 

$\ce{CO3}$ decomposes slowly enough that it may come into contact with other molecules (including biomolecules), but nothing is known of its possible oxidizing potential.

$\ce{CO4},$ $\ce{CO5}$ and $\ce{CO6}$ are very unstable, and could possibly be strong oxidants (though it may never be known since they're too unstable).

Other than that, any information?
At least the trioxide $\ce{CO3}$ exists, and it has even been detected in at least two isomeric forms.  Wikipedia reports that it forms as a transient species in reactions between carbon dioxide and atomic oxygen or ozone, in irradiation of solid carbon dioxide, and even in oxidation of carbon monoxide by $\ce{O2}$.