Caesium azide

Caesium azide or cesium azide is an inorganic compound of caesium and nitrogen. It is a salt of azide with the formula CsN₃.

Caesium azide

Coordination sphere of azide in CsN3
Names
IUPAC name caesium azide
Other names cesium azide
Identifiers
CAS Number	22750-57-8
3D model (JSmol)	Interactive image
ChemSpider	81071
ECHA InfoCard	100.041.072
EC Number	245-196-0
PubChem CID	6101636
CompTox Dashboard (EPA)	DTXSID601014422 DTXSID60929869, DTXSID601014422
InChI InChI=1S/Cs.N3/c;1-3-2/q+1;-1 Key: AYTVLULEEPNWAX-UHFFFAOYSA-N InChI=1S/Cs.N3/c;1-3-2/q+1;-1
SMILES [N-]=[N+]=[N-].[Cs+]
Properties[1]
Chemical formula	CsN3
Molar mass	174.926 g/mol
Appearance	colorless needles
Density	3.5 g/cm3
Melting point	310 °C (590 °F; 583 K)
Solubility in water	224.2 g/100 mL (0 °C)
Structure[2]
Crystal structure	tetragonal
Space group	I4/mcm, No. 140
Lattice constant	a = 6.5412 Å, c = 8.0908 Å
Formula units (Z)	4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Structure

CsN₃ adopts the same structure as KN₃, RbN₃, and TlN₃, crystallizing in a tetragonal distorted caesium chloride structure where each azide ion coordinates to eight metal cations, and each metal cation coordinates to eight terminal N centers.^[2] When heated to 151 °C, it transitions to a cubic structure.^[3]

Preparation and reactions

Caesium azide can be prepared from the neutralization reaction between hydrazoic acid and caesium hydroxide:^[4]

CsOH + HN₃ → CsN₃ + H₂O

Caesium carbonate can also be used as the base:

Cs₂CO₃ + HN₃ → CsN₃ + CO₂ + H₂O

Caesium sulfate reacts with barium azide to form insoluble barium sulfate and caesium azide:

Cs₂SO₄ + Ba(N₃)₂ → 2CsN₃ + BaSO₄↓

The thermal decomposition of CsN₃ in vacuo can be used as a method of generating high purity caesium metal:^[5]

2 CsN₃ → 2 Cs + 3 N₂