Direct Observation of Cyclo‐Pentazolate Anion Decomposition in a Tailored Molecular Trap

The cyclo‐pentazolate anion (cyclo‐N5ˉ) has garnered significant attention as an all‐nitrogen, five‐membered‐ring ion with a high‐energy state and unique aromaticity. Typically, the free cyclo‐N5ˉ anion is a highly unstable species, and its stabilization relies on strong interactions, such as a hydrogen bonding network or metal coordination. However, these interactions often compromise the independence of the anion, thus diminishing its aromaticity. Here, we present a molecular trap designed to encapsulate and isolate cyclo‐N5ˉ through collective weak interactions. This approach utilizes a pre‐positioned ion to subsequently displace the cyclo‐N5ˉ anion into the cage cavity, addressing the challenge posed by the absence of strong‐interaction‐driven binding. This setup preserves the aromaticity of the anion to a significant extent, as predicted by computational studies. More importantly, the decomposition of free cyclo‐N5ˉ within the microenvironment was directly recorded for the first time using single crystal X‐ray diffraction analysis.