{{cs1 config|name-list-style=vanc|display-authors=6}} {{This|the linear structure|the theoretical cyclic structure|hexazine}} {{Chembox | ImageFile = Hexanitrogen.svg | ImageSize = 180px | ImageAlt = | IUPACName = hexaaza-1,2,4,5-tetraene | OtherNames = Hexanitrogen |Section1={{Chembox Identifiers | CASNo = | ChemSpiderID = | PubChem = 23527683 | StdInChI= 1S/N6/c1-3-5-6-4-2 | StdInChIKey = UCDGJNRDJKMFBS-UHFFFAOYSA-N | SMILES = [N-]=[N+]=NN=[N+]=[N-] }} |Section2={{Chembox Properties | N = 6 | MolarMass = | Appearance = colorless | Density = | MeltingPtC = | BoilingPt = | Solubility = }} |Section3={{Chembox Hazards | MainHazards = | FlashPt = | AutoignitionPt = }} |Section8={{Chembox Related | OtherCompounds = Hexazine, Pentazolate, Pentazole }} }} '''Hexanitrogen''' ('''diazide''', '''hexaaza-1,2,4,5-tetraene''') is an allotrope of nitrogen with the formula N<sub>6</sub>. 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<ref>{{cite journal |doi= 10.1021/acs.jpca.6b01655 |title= A New Allotrope of Nitrogen as High-Energy Density Material |date= 2016 |last1= Greschner |first1= Michael J. |last2= Zhang |first2= Meng |last3= Majumdar |first3= Arnab |last4= Liu |first4= Hanyu |last5= Peng |first5= Feng |last6= Tse |first6= John S. |last7= Yao |first7= Yansun |journal= The Journal of Physical Chemistry A |volume= 120 |issue= 18 |pages= 2920–2925 |pmid= 27088348 |bibcode= 2016JPCA..120.2920G }}</ref> and its synthesis was reported in 2025.<ref name="Qian_2025"/> It is stable at cryogenic temperatures.<ref name="Qian_2025">{{cite journal | vauthors = Qian W, Mardyukov A, Schreiner PR | title = Preparation of a neutral nitrogen allotrope hexanitrogen ''C''<sub>2h</sub>-N<sub>6</sub> | journal = Nature | volume = 642 | issue = 8067 | pages = 356–360 | date = June 2025 | pmid = 40500322 | pmc = 12158757 | doi = 10.1038/s41586-025-09032-9 }}</ref> The higher symmetry analogue, the benzene-like cyclic hexazine, has remained only theoretically hypothesized.
Its synthesis has been regarded as highly significant, as higher allotropes of nitrogen have potential application as propellants, explosives or energy storage.<ref>{{cite journal | vauthors = Halford B | title = A new nitrogen allotrope has been created at last. | journal = Chemical & Engineering News | date = 11 June 2025 | url = https://cen.acs.org/materials/inorganic-chemistry/new-nitrogen-allotrope-created-last/103/web/2025/06 }}</ref><ref>{{cite web | vauthors = Wogan T | title = Most energetic molecule ever made is stable – in liquid nitrogen. | date = 13 June 2025 | url = https://www.chemistryworld.com/news/most-energetic-molecule-ever-made-is-stable-in-liquid-nitrogen/4021662.article | work = Chemistry World }}</ref><ref>{{cite web | vauthors = Mondal S | title = Successful synthesis of neutral N<sub>6</sub> opens door for future energy storage. | date = 18 June 2025 | url = https://phys.org/news/2025-06-scientists-stable-neutral-nitrogen-allotrope.html | work = phys.org }}</ref>
==Synthesis==
It is synthesized by the reaction of silver azide (AgN<sub>3</sub>) 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).<ref name="Qian_2025" /> :File:Hexanitrogen synthesis01.svg :File:Hexanitrogen synthesis02.svg
==Structure== All six atoms form a single chain, resembling two azide (N<sub>3</sub>) units linked together. :thumb|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.<ref name="Qian_2025" />
==See also== *Dinitrogen *Trinitrogen *Tetranitrogen *Hexazine *Octaazacubane *Black nitrogen *Other allotropes of nitrogen
==References== {{reflist}}
Category:Azides Category:Allotropes of nitrogen
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