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 applicat ...
side chain connected to the carbon atom. Several salts exist, but they are unstable and spontaneously explode.
Rubidium azidotetrazolate was so unstable that it explodes while crystallizing.
[ The potassium and caesium salt also spontaneously explode when dry.][
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 chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...
. 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 formula (CN)Br or 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 compounds. ...
and sodium azide in water:[
BrCN + 2NaN3 → N4CN3− + Na+ + NaBr
]
Salts
Related
Chemicals related to the azidotetrazolate anion include 1-diazidocarbamoyl-5-azidotetrazole
1-Diazidocarbamoyl-5-azidotetrazole, often jokingly referred to as azidoazide azide, is a heterocyclic inorganic compound with the formula C2N14. It is an extremely sensitive explosive.
Synthesis
1-Diazidocarbamoyl-5-azidotetrazole was produced ...
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