Fluorine azide

Fluorine azide or triazadienyl fluoride is a yellow green gas composed of nitrogen and fluorine with formula FN₃.^[1] Its properties resemble those of ClN₃, BrN₃, and IN₃.^[2] The bond between the fluorine atom and the nitrogen is very weak, leading to this substance being very unstable and prone to explosion.^[3] Calculations show the F–N–N angle to be around 102° with a straight line of 3 nitrogen atoms.^[4]

Fluorine azide

Names
Other names triazadienyl fluoride
Identifiers
CAS Number	14986-60-8 Y
3D model (JSmol)	Interactive image
ChemSpider	10328964
PubChem CID	23235952
CompTox Dashboard (EPA)	DTXSID40631418
InChI InChI=1S/FN3/c1-3-4-2 Key: AJXWEJAGUZJGRI-UHFFFAOYSA-N
SMILES [N-]=[N+]=NF
Properties
Chemical formula	FN3
Molar mass	61.019 g/mol
Appearance	Yellow-green gas
Melting point	−139 °C (−218 °F; 134 K)
Boiling point	−30 °C (−22 °F; 243 K)
Explosive data
Shock sensitivity	Extreme
Friction sensitivity	Extreme
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Extremely sensitive explosive
NFPA 704 (fire diamond)	[citation needed] 0 4
Related compounds
Other cations	Hydrazoic acid Chlorine azide Bromine azide Iodine azide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

The gas boils at –30° and melts at –139 °C.^[5]

It was first made by John F. Haller in 1942.^[6]

Reactions

Fluorine azide can be made by reacting hydrazoic acid or sodium azide, with fluorine gas.^[5][7]

HN₃ + F₂ → N₃F + HF

NaN₃ + F₂ → N₃F + NaF

Fluorine azide decomposes without explosion at normal temperatures to make dinitrogen difluoride:

2 FN₃ → N₂F₂ + 2 N₂.^[1]

At higher temperatures such as 1000 °C fluorine azide breaks up into nitrogen monofluoride radical:^[7]

FN₃ → NF + N₂

The FN itself dimerizes on cooling.

2 NF → N₂F₂

Solid or liquid FN₃ can explode, releasing a large amount of energy. A thin film burns at the rate of 1.6 km/s.^[8] Due to the explosion hazard, only very small quantities of this substance should be handled at a time.^[9]

FN₃ adducts can be formed with the Lewis acids boron trifluoride (BF₃) and arsenic pentafluoride (AsF₅) at -196 °C. These molecules bond with the first nitrogen atom from the fluorine.^[10]

Properties

Spectroscopy

Parameter	Value[9]	Unit
A	48131.448	MHz
B	5713.266	MHz
C	5095.276	MHz
μa	1.1
μb	0.7

Shape

Distances between atoms are F–N 0.1444 nm, FN=NN 0.1253 nm and FNN=N 0.1132 nm.^[9]

Physical

FN₃ has a density of 1.3 g/cm³.^[11]

FN₃ adsorbs on to solid surfaces of potassium fluoride, but not onto lithium fluoride or sodium fluoride. This property was being investigated so that FN₃ could boost the energy of solid propellants.^[11]

The ultraviolet photoelectric spectrum shows ionisation peaks at 11.01, 13,72, 15.6, 15.9, 16.67, 18.2, and 19.7 eV. Respectively these are assigned to the orbitals: π, n_N or n_F, n_F, π_F, n_N or σ, π and σ.^[3]