Fluorine azide or triazadienyl fluoride is a yellow green gas composed of
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
and
fluorine
Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactiv ...
with formula .
It is counted as an interhalogen compound, as the azide functional group is termed a
pseudohalogen
Pseudohalogens are polyatomic analogues of halogens, whose chemistry, resembling that of the true halogens, allows them to substitute for halogens in several classes of chemical compounds. Pseudohalogens occur in pseudohalogen molecules, inorganic ...
. It resembles
,
, and
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–N angle to be around 102° with a straight line of 3 nitrogen atoms.
The gas boils at –30° and melts at –139 °C.
It was first made by John F. Haller in 1942.
Reactions
Fluorine azide can be made by reacting
hydrazoic acid
Hydrazoic acid, also known as hydrogen azide or azoimide, This also contains a detailed description of the contemporaneous production process. is a compound with the chemical formula . It is a colorless, volatile, and explosive liquid at room tem ...
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
Dinitrogen difluoride is a chemical compound with the formula N2F2. It is a gas at room temperature, and was first identified in 1952 as the thermal decomposition product of the azide N3F. It has the structure F−N=N−F and exists in both a '' ...
:
:.
At higher temperatures such as 1000 °C fluorine azide breaks up into
nitrogen monofluoride
Nitrogen monofluoride (fluoroimidogen) is a metastable species that has been observed in laser studies. It is isoelectronic with O2. Like boron monofluoride, it is an instance of the rare multiply-bonded fluorine atom. It is unstable with respec ...
radical:
:
The FN itself dimerizes on cooling.
:
Solid or liquid 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.
adduct
An adduct (from the Latin ''adductus'', "drawn toward" alternatively, a contraction of "addition product") is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all co ...
s can be formed with the
Lewis acid
A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...
s
boron trifluoride
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.
Structure and bond ...
() and
arsenic pentafluoride () at -196 °C. These molecules bond with the N
α atom.
Properties
Spectroscopy
Shape
Distances between atoms are F–N 0.1444 nm, FN=NN 0.1253 nm and FNN=N 0.1132 nm.
Physical
has a density of 1.3 g/cm
3.
adsorb
Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid or dissolved solid to a surface. This process creates a film of the ''adsorbate'' on the surface of the ''adsorbent''. This process differs from absorption, in which a f ...
s on to solid surfaces of
potassium fluoride, but not onto
lithium fluoride or
sodium fluoride
Sodium fluoride (NaF) is an inorganic compound with the formula . It is used in trace amounts in the fluoridation of drinking water, in toothpaste, in metallurgy, and as a flux. It is a colorless or white solid that is readily soluble in water. I ...
. This property was being investigated so that could boost the energy of solid propellants.
The ultraviolet
photoelectric spectrum
Photoemission spectroscopy (PES), also known as photoelectron spectroscopy, refers to energy measurement of electrons emitted from solids, gases or liquids by the photoelectric effect, in order to determine the binding energies of electrons in th ...
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.
References
External links
*
{{Azides
Fluorine compounds
Azido compounds
Gases with color
Explosive gases
Explosive chemicals
Pseudohalogens