Caesium ozonide

Caesium ozonide is an oxygen-rich chemical compound of caesium, with the chemical formula CsO₃. It consists of caesium cations Cs⁺ and ozonide anions O−3. It can be formed by reacting ozone with caesium superoxide:^[2][3]

CsO₂ + O₃ → CsO₃ + O₂

Caesium ozonide

Caesium cations, Cs+   Ozonide anions, O−3
Caesium ozonide contaminated with caesium superoxide
Names
IUPAC name Caesium ozonide
Identifiers
CAS Number	12053-67-7
3D model (JSmol)	Interactive image
InChI InChI=1S/Cs.HO3/c;1-3-2/h;1H/q+1;/p-1 Key: SLQRFWQASSLHIF-UHFFFAOYSA-M
SMILES [Cs+].[O-]O[O]
Properties
Chemical formula	CsO3
Molar mass	180.902 g·mol−1
Appearance	Dark cherry red powder[1]
Density	3.19 g/cm3[1]
Melting point	85 °C (185 °F; 358 K) (decomposes)
Related compounds
Other anions	Caesium fluoride Caesium chloride Caesium bromide Caesium iodide
Other cations	Sodium ozonide Potassium ozonide Rubidium ozonide
Related caesium oxides	Caesium suboxide Caesium monoxide Caesium peroxide Caesium sesquioxide Caesium superoxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The compound reacts strongly with any water in the air forming caesium hydroxide.^[3]

4 CsO₃ + 2 H₂O → 4 CsOH + 5 O₂

If heated to between 70 and 100 °C, caesium ozonide will quickly decompose to caesium superoxide (CsO₂).^[3] In fact, the compound is metastable to decomposition into caesium superoxide, slowly decomposing at room temperature, but can remain intact for months if stored at −20 °C.^[4]

Above around 8 °C, the crystal structure is of the caesium chloride type, with the ozonide ion in place of the chloride ion. At lower temperatures, the crystal structure changes to a structure identical to rubidium ozonide (RbO₃), with space group P2₁/c.^[2]