Azidotetrazolate

Azidotetrazolate CN₇⁻ is a highly explosive series of salts and an anion. 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 a side azido chain connected to the carbon atom. Several salts exist, but they are unstable and spontaneously explode.^[1] Rubidium azidotetrazolate was so unstable that it explodes 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.^[1]

Formation

The azidotetrazolate ion can be made from cyanogen bromide and sodium azide in water:^[1]

BrCN + 2NaN₃ → N₄CN₃⁻ + Na⁺

Salts

formula^[1]	name	molecular weight	density	structure	unit dell dimension Å	cell volume	formula per cell	Specific impuse
NH₄CN₇	Ammonium azidotetrazolate	128.12	1.608	monoclinic	a=3.9103 b=6.9140 c=9.9127 β=99.177°	264.57	2	248
N₂H₅CN₇	Hydrazinium azidotetrazolate	143.14	1.568	monoclinic	a=10.8114 b=7.4641 c=7.6676 β=101.437°	606.47	4	265
CN₃H₆CN₇	guanidinium azidotetrazolate semihydrate	358.35	1.546	monoclinic	a=9.5374 b=15.3120 c=10.5731 β=94.361	1539.6	4
CN₄H₇CN₇	aminoguanidinium azidotetrazolate	185.19	1.524	triclinic	a=9.7652 b=9.7803 c=10.0434 α=71.327° β=74.399° γ=63.962°	807.2	4	228
LiCN₇•H₂O	Lithium azidotetrazolate monohydrate	135.03	1.683	monoclinic	a=8.9207 b=4.6663 c=12.8648 β=95.608	532.96	4
NaCN₇•H₂O	sodium azidotetrazolate monohydrate	151.09	1.743	monoclinic	a=11.203 b=7.138 c=14.409 β=91.630°	1151.8	8
KCN₇	Potassium azidotetrazolate	149.18	1.917	monoclinic	a=9.7759 b=6.2990 c=8.4533 β=96.720°	516.96	4
RbCN₇	Rubidium azidotetrazolate
CsCN₇	Caesium azidotetrazolate	242.99	2.810	orthorhombic	a=4.3082 b=7.1345 c=18.6869	574.38	4
3Ca(CN₇)₂•16H₂O	Calcium azidotetrazolate	1068.98	1.657	monoclinic	a=24.448 b=6.616 c=28.057 β=109.246°	4285	4
AgCN₇	silver azidotetrazolate

References

^ ^a ^b ^c ^d Klapötke, Thomas M.; Stierstorfer, Jörg (28 January 2009). "The CN7- Anion". Journal of the American Chemical Society. 131 (3): 1122–1134. doi:10.1021/ja8077522.

[clap9-1] Klapötke, Thomas M.; Stierstorfer, Jörg (28 January 2009). "The CN7- Anion". Journal of the American Chemical Society. 131 (3): 1122–1134. doi:10.1021/ja8077522.

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