The best part is the Methods section, which opens with

> Warning! Silver azide and halogen azides are extremely hazardous and explosive. Such compounds should be handled with utmost care and only in very small quantities (<5 mmol). Appropriate safety precautions (blast screens, face shields, Kevlar gloves, soundproof earmuffs and protective leather clothing) are necessary. Make sure to eliminate static electricity before handling. It is also crucial to avoid friction and light exposure and prevent any contact with metals during sample handling to ensure safety.

That is, please do the synthesis in full armor, in the dark and don't touch anything more than strictly necessary.

Also wear ear protection, because it's still going to go bang.

I like the green energy twist in the intro too. "High-energy materials" is an euphemism chemists engaged in weapons research like to use. I went to some conference talks about high energy materials before, and research presented at those talks was always funded by various defence agencies. But maybe that's just a North American thing, this particular group only acknowledges funding from the innocuous Deutsche Forschungsgemeinschaft.

> Compounds consisting only of the element nitrogen [...] are considered promising clean energy-storage materials

They are not actually serious about this, right?

I feel if that directly acknowledging Klapötke of all people is basically a thinly veiled concession that watever you synthesized is too explosive to even be used as an explosive. As seems to be the case here.

Is there even a remotely possibility for this to be used in any practical application?

Noneteless, impressive paper, and getting that abstract into Nature is basically an achievement on its own already.

- "decomposition of N6 into three N2 is exothermic (ΔH₀) by 185.2 kcal mol−1"

That's an impressive amount of energy, 9.2e6 J/kg—on the same order as carbon combustion. Wonder if it's a potential rocket fuel additive (it probably isn't, but fun to ask). By comparison, O₃ is "only" 3.0e6 J/kg above diatomic oxygen.

> "is unlikely to decompose through [quantum mechanical tunneling], with an estimated half-life of N6 of more than 132 years at 77 K (Supplementary Table 4). At 298 K, the computed half-life still amounts to 35.7 ms"

Better hope that fridge doesn't fail.

Note that "C2h" is the symmetry[1] and "N6" is the chemical formula. Yes, 6 Nitrogen in a line, N-N-N-N-N-N with some weird bounds and internal charges, probably a good candidate to "Things I Won't Work With" in https://www.science.org/blogs/pipeline From the article:

> Detonation calculation details

[1] See for example another molecule with a different shape but the same symmetry in https://www.cup.uni-muenchen.de/ch/compchem/geom/sym_C2h.htm...

> [Nitrogen compounds] are considered promising clean energy-storage materials owing to their immense energy content that is much higher than hydrogen, ammonia or hydrazine, which are in common use, and because they release only harmless nitrogen on decomposition.

What the abstract mentions only sideways is that a key use of these properties is production of explosives - nitroglycerin, trinitrotoluene (TNT) or nitrocellulose (modern gunpowder) come to mind, and indeed, they store a lot of energy. Note all have "nitro" in the name.

At this point I'm not sure you care that only exhaust gas is nitrogen.

> Here we present the room-temperature preparation of molecular N6 (hexanitrogen) through the gas-phase reaction of chlorine or bromine with silver azide

Hmmm, chlorine and bromine - off to a good start - then we come to silver azide.

"Azide" immediately rings all my Derek Lowe bells, and yeah... it's exactly what you'd expect.