organic anion oxoanion carbon oxoanion oxocarbon anions chebi_ontology A negative ion consisting solely of carbon and oxygen atoms, and therefore having the general formula C<small>_<em>x</em></small>O<small>_<em>y</em></small><small>^{<em>n</em>−</small>} for some integers <em>x</em>, <em>y</em> and <em>n</em>. oxocarbon anion CHEBI:35604 carbon oxoanions carbon oxoanion organooxygen compound