Fluorine azide

Fluorine azide

200px
200px
Names
Other names triazadienyl fluoride
Identifiers
CAS Number	14986-60-8 Y
Jmol 3D model	Interactive image
PubChem	23235952
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	−152 °C (−242 °F; 121 K)
Boiling point	−82 °C (−116 °F; 191 K)
Explosive data
Shock sensitivity	Extreme
Friction sensitivity	Extreme
Vapor pressure	{{{value}}}
Related compounds
Related compounds	Hydrazoic acid Chlorine azide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Fluorine azide or triazadienyl fluoride FN₃ is a yellow green gas composed of nitrogen and fluorine with formula FN₃. It is counted as an interhalogen compound, as the azide functional group is termed a pseudohalogen. It resembles ClN₃, BrN₃, IN₃ in this respect. The bond between the fluorine atom and the nitrogen is very weak, leading to this substance being very unstable and prone to explosion. Calculations show the F—N angle to be around 102° with a straight line of 3 nitrogen atoms.

The gas liquifies at –82° and can be turned to a solid at –152 °C.

It was first made by John F. Haller in 1942.

Reactions

Fluorine azide can be made by reacting hydrazoic acid and fluorine gas.

Another way to form it is by reacting sodium azide with fluorine.

Fluorine azide decomposes without explosion at normal temperatures to make dinitrogen difluoride. 2 FN₃ → N₂F₂ + 2N₂.

At higher temperatures such as 1000 °C fluorine azide breaks up into nitrogen monofluoride radical. FN₃ → FN{a¹Δ} + N₂.

Solid or liquid FN₃ explodes, releasing much heat. A thin film burns at the rate of 1.6 km/s. Because the explosion hazard is great only very small quantities of this substance should be handled at a time. A 0.02 g limit is recommended for experiments.

N₃F adducts can be formed with the Lewis acids boron trifluoride (BF₃) and arsenic pentafluoride (AsF₅) at -196 °C. These molecules bond with the N_α atom.

Properties

Spectroscopy

parameter	value	unit
A	48131.448	MHz
B	5713.266	MHz
C	5095.276	MHz
μa	1.1
μb	0.7

Shape

The nitrogen atoms in this molecule can be labelled with Greek letters: N_α for nitrogen attached to fluorine, N_β for the intermediate nitrogen, and N_γ for the terminal nitrogen. The terminal nitrogen can also be labelled N_ω.

Distances between atoms are F-N 0.1444 nm, FN-NN 0.1253 nm and FNN-N 0.1132 nm.

Physical

N₃F has a density of 1.3 g/cm³.

N₃F adsorbs on to solid surfaces of potassium fluoride, but not onto lithium fluoride or sodium fluoride. This property was being investigated so that N₃F could boost the energy of solid propellants.

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.