Azidotetrazolate (CN
7−) is an anion which forms a highly explosive series of salts. The ion is made by removing a proton from
5-azido-1H-tetrazole. The molecular structure contains a five-membered ring with four nitrogen atoms, and an
azido
In chemistry, azide (, ) is a linear, polyatomic anion with the formula and structure . It is the conjugate base of hydrazoic acid . Organic azides are organic compounds with the formula , containing the azide functional group. The dominant a ...
side chain connected to the carbon atom. Several salts exist, but they are unstable and spontaneously explode.
For example, the rubidium, potassium and caesium salts are so unstable that they explode while crystallizing.
[
Azidotetrazolates are under investigation for use as bullet propellant, rocket propellants and high explosives. The nitrogen base compounds have the advantage of being "green explosives", meaning that their waste products are safe.][ Amongst the tetrazolates, they have the highest nitrogen fraction.
]
Properties
Different stimuli can set off explosions. Possibilities include impact, friction, sparks or heat. Guanidinium azidotetrazolate could be melted to an ionic liquid at 100°C, but would decompose smoothly at 159°. Sodium azidotetrazolate explodes when the temperature reaches 155°C.[
The CNNNN ring in azidotetrazolate is planar and ]aromatic
In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...
. The NNN side chain is attached to the carbon atom, and bent at the first nitrogen so that it is roughly parallel to the ring.
The base acids, 5-azido-1''H''-tetrazole and 5-azido-2''H''-tetrazole both can exist. The 1''H'' version has a hydrogen atom bonded to a nitrogen atom next to the carbon. It is the stable form in solids and solutions in polar liquids. This is explained by a favourable hydrogen bond, and a greater dipole moment. The 2''H'' version with hydrogen attached in the second nitrogen from the carbon is purportedly more stable in the gas phase.
Formation
The azidotetrazolate ion can be made from cyanogen bromide
Cyanogen bromide is the inorganic compound with the chemical formula, formula BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides (cuts the C-terminus of methionine), and synthesize other compo ...
and sodium azide
Sodium azide is an inorganic compound with the formula . This colorless salt is the gas-forming component in some car airbag systems. It is used for the preparation of other azide compounds. It is highly soluble in water and is acutely poisonou ...
in water:[
BrCN + 2NaN3 → N4CN3− + Na+ + NaBr
]
Salts
Related
Chemicals related to the azidotetrazolate anion include 1-diazidocarbamoyl-5-azidotetrazole with the same percentage of nitrogen.
References
External links
*{{cite web, last1=Derek, first1=Lowe, title=Things I Won't Work With: Azidotetrazolate Salts, url=https://www.science.org/content/blog-post/things-i-won-t-work-azidotetrazolate-salts, website=In the Pipeline, accessdate=11 February 2018, date=7 January 2009
Tetrazoles
Organoazides