The fuel comes with its own oxygen atoms to help it burn.
Either class can have the oxygen atoms attached at various positions around the rings.
A single oxygen atom can bridge to two metal centers.
Focus attention on the oxygen atoms in one set: there are N/2 of them.
The negative charge is spread likewise between the oxygen atoms.
An oxygen atom is not always required for oxidation either.
In a more specific sense, it can be a chemical that releases oxygen atoms.
It is made of one carbon and two oxygen atoms.
Therefore, oxygen atoms need to stay far from each other in order to reduce the repulsive force between them.
