Ozonide

Ozonide is an unstable, reactive polyatomic anion O−
3, derived from ozone, or an organic compound similar to organic peroxide formed by a reaction of ozone with an unsaturated compound.

Inorganic ozonides are dark red ionic compounds containing the reactive O−
3 anion. The anion has the V-shape of the ozone molecule.

Inorganic ozonides are formed by burning potassium, rubidium, or caesium in ozone, or by treating the alkali metal hydroxide with ozone; if potassium is left undisturbed in air for years it accumulates a covering of superoxide and ozonide. They are very sensitive explosives that have to be handled at low temperatures in an atmosphere consisting of an inert gas. Lithium and sodium ozonide are extremely unstable and must be prepared by low-temperature ion exchange starting from CsO₃. Sodium ozonide, NaO
3, which is prone to decomposition into NaOH and NaO
2, was previously thought to be impossible to obtain in pure form. However, with the help of cryptands and methylamine, pure NaO
3 may be obtained as red crystals isostructural to NaNO
2.