Pentazenium tetraazidoborate

Pentazenium tetraazidoborate
Names
	Other names Pentanitrogen tetraazidoborate
Identifiers
3D model (JSmol)	Interactive image;
	InChI InChI=1S/BN12.N5/c2-10-6-1(7-11-3,8-12-4)9-13-5;1-3-5-4-2/q-1;+1 Key: OFPGSIWCLXGVQI-UHFFFAOYSA-N;
	SMILES [N-]=[N+]=N[N+]#N.[B-](N=[N+]=[N-])(N=[N+]=[N-])(N=[N+]=[N-])N=[N+]=[N-];
Properties
Chemical formula	BN17
Molar mass	248.92 g/mol
Appearance	White solid
Melting point	−63 °C (−81 °F; 210 K) (decomposes)
Solubility	Soluble in sulfur dioxide
Explosive data
Detonation velocity	Very high
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Pentazenium tetraazidoborate is an extremely unstable chemical compound with the formula N₅[B(N₃)₄]. It is a white solid that violently explodes at room temperature. This compound has a 95.7% nitrogen content which is the second highest known of a chemical compound, exceeding even that of ammonium azide (93.3%) and 1-diazidocarbamoyl-5-azidotetrazole (89.1%),^[1] being surpassed only by hydrazoic acid (97.7%).

Production and properties

The production of N₅[B(N₃)₄] requires a multi-step synthesis, first, hydrazoic acid and sodium borohydride is reacted in diethyl ether at -78 °C to produce sodium tetraazidoborate (which decomposes at 76 °C):^[2]

NaBH₄ + 4HN₃ → Na[B(N₃)₄] + 4H₂

The other reactant, pentazenium hexafluoroantimonate, its produced by the reaction of N₂F⁺ and antimony(V) fluoride. Then, two reactants that are produced are mixed at -64 °C under sulfur dioxide:^[1]

Na[B(N₃)₄] + N₅SbF₆ → N₅[B(N₃)₄] + NaSbF₆↓

to produce the pentazenium tetraazidoborate. If heated, it decomposes into nitrogen gas and boron triazide; the boron triazide further decomposes into boron nitride and nitrogen. The overall reaction is the following:^[3]

N₅[B(N₃)₄] → 8N₂ + BN

The compound is extremely sensitive, an attempted Raman spectroscopy of a 500 mg sample of the compound resulted in an explosion.^[1]

References

^ ^a ^b ^c Ralf Haiges Dr.; Stefan Schneider Dr.; Thorsten Schroer Dr.; Karl O. Christe Prof. Dr. (2004). "High-Energy-Density Materials: Synthesis and Characterization of N5+[P(N3)6]−, N5+ [B(N3)4]−, N5+ [HF2]−⋅n HF, N5+ [BF4]−, N5+ [PF6]−, and N5+ [SO3F]−". Angewandte Chemie International Edition. 43 (37). Wiley: 4919–4924. doi:10.1002/anie.200454242. PMID 15372568.
^ Wolfgang Fraenk; Tassilo Habereder; Anton Hammerl; Thomas M. Klapötke; Burkhard Krumm; Peter Mayer; Heinrich Nöth; Marcus Warchhold (2001). "Highly Energetic Tetraazidoborate Anion and Boron Triazide Adducts". Inorganic Chemistry. 40 (6). ACS Publications: 1334–1340. doi:10.1021/ic001119b. PMID 11300838.
^ Itai Zakai; Dan Grinstein; Shmuel Welner; R. Benny Gerber (2019). "Structures, Stability, and Decomposition Dynamics of the Polynitrogen Molecule N5+B(N3)4– and Its Dimer [N5+]2[B(N3)4–]2". The Journal of Physical Chemistry A. 123 (34). ACS Publications: 7384–7393. Bibcode:2019JPCA..123.7384Z. doi:10.1021/acs.jpca.9b03704. PMID 31381345. S2CID 199451470.

[pre-1] Ralf Haiges Dr.; Stefan Schneider Dr.; Thorsten Schroer Dr.; Karl O. Christe Prof. Dr. (2004). "High-Energy-Density Materials: Synthesis and Characterization of N5+[P(N3)6]−, N5+ [B(N3)4]−, N5+ [HF2]−⋅n HF, N5+ [BF4]−, N5+ [PF6]−, and N5+ [SO3F]−". Angewandte Chemie International Edition. 43 (37). Wiley: 4919–4924. doi:10.1002/anie.200454242. PMID 15372568.

[boron-2] Wolfgang Fraenk; Tassilo Habereder; Anton Hammerl; Thomas M. Klapötke; Burkhard Krumm; Peter Mayer; Heinrich Nöth; Marcus Warchhold (2001). "Highly Energetic Tetraazidoborate Anion and Boron Triazide Adducts". Inorganic Chemistry. 40 (6). ACS Publications: 1334–1340. doi:10.1021/ic001119b. PMID 11300838.

[stable-3] Itai Zakai; Dan Grinstein; Shmuel Welner; R. Benny Gerber (2019). "Structures, Stability, and Decomposition Dynamics of the Polynitrogen Molecule N5+B(N3)4– and Its Dimer [N5+]2[B(N3)4–]2". The Journal of Physical Chemistry A. 123 (34). ACS Publications: 7384–7393. Bibcode:2019JPCA..123.7384Z. doi:10.1021/acs.jpca.9b03704. PMID 31381345. S2CID 199451470.

[1]

[2]

[3]