Oxocarbon anion

There are however a large number of stable anions in this class, including several ones that have research or industrial use.

There are also many unstable anions, like CO−2 and CO4−, that have a fleeting existence during some chemical reactions; and many hypothetical species, like CO4−4, that have been the subject of theoretical studies but have yet to be observed.

Unstable anions may persist in very rarefied gaseous state, such as in interstellar clouds.

Most oxocarbon anions have corresponding moieties in organic chemistry, whose compounds are usually esters.

The carbon atom has 4 pairs of valence electrons, which shows that the molecule obeys the octet rule.

With valence bond theory the electronic structure of the carbonate ion is a resonance hybrid of 3 canonical forms.

The correspondence is not always well-defined since there may be several ways of performing this formal dehydration, including joining two or more anions to make an oligomer or polymer.