Hexanitrogen

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Hexanitrogen
Hexanitrogen.svg
Names
IUPAC name
hexaaza-1,2,4,5-tetraene
Other names
Hexanitrogen
Identifiers
3D model (JSmol)
PubChem CID
  • InChI=1S/N6/c1-3-5-6-4-2
    Key: UCDGJNRDJKMFBS-UHFFFAOYSA-N
  • [N-]=[N+]=NN=[N+]=[N-]
Properties
N6
Molar mass 84.042 g·mol−1
Appearancecolorless
Related compounds
Related compounds
 Hexazine, Pentazolate, Pentazole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Hexanitrogen (diazide, hexaaza-1,2,4,5-tetraene) is an allotrope of nitrogen with the formula N6. The six nitrogen atoms are all covalently bonded in a single molecule: two azide units linked to each other. Its stability and structure were theorized in 2016 [1] and its synthesis was reported in 2025. [2] It is stable at cryogenic temperatures. [2]

Contents

Its synthesis has been regarded as highly significant, as higher allotropes of nitrogen have potential application as propellants, explosives or energy storage. [3] [4] [5]

Synthesis

It is synthesized by the reaction of silver azide (AgN3) with chlorine or bromine gas under reduced pressure at room temperature via chlorine azide or bromine azide as the intermediate. The product is collected by matrix isolation in solid argon (10  K) or by condensation on a liquid nitrogen cooled surface (77 K). [2]

Hexanitrogen synthesis01.svg
Hexanitrogen synthesis02.svg

Structure

All six atoms form a single chain, resembling two azide (N3) units linked together.

Bond lengths and angles in hexanitrogen Hexanitrogen bonds.svg
Bond lengths and angles in hexanitrogen

Computational analysis predicts that the bond lengths in the molecule vary significantly, indicating a complex electronic distribution, and a trans geometry in the central part of the structure. The terminal double bonds (N1=N2 and N5=N6) are about 1.138 Å. The adjacent double bonds (N2=N3 and N4=N5) are slightly longer, about 1.251 Å, and the central single bond (N3–N4) is the longest, about 1.460 Å. Each azide-like unit is approximately linear, with bond angles of about 172.5° at N2 and N5, and distinctly bent geometry of about 107° at N3 and N4. [2]

References

  1. ↑ Greschner MJ, Zhang M, Majumdar A, Liu H, Peng F, Tse JS, et al. (2016). "A New Allotrope of Nitrogen as High-Energy Density Material". The Journal of Physical Chemistry A. 120 (18): 2920–2925. Bibcode:2016JPCA..120.2920G. doi:10.1021/acs.jpca.6b01655. PMID   27088348.
  2. 1 2 3 4 Qian W, Mardyukov A, Schreiner PR (June 2025). "Preparation of a neutral nitrogen allotrope hexanitrogen C2h-N6". Nature. 642 (8067): 356–360. doi:10.1038/s41586-025-09032-9. PMC   12158757 . PMID   40500322.
  3. ↑ Halford B (11 June 2025). "A new nitrogen allotrope has been created at last". Chemical & Engineering News.
  4. ↑ Wogan T (13 June 2025). "Most energetic molecule ever made is stable – in liquid nitrogen". Chemistry World.
  5. ↑ Mondal S (18 June 2025). "Successful synthesis of neutral N6 opens door for future energy storage". phys.org.
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