Pentazole

"Pentazole is an aromatic chemical molecule consisting of a five-membered ring with all nitrogen atoms, one of which is bonded to a hydrogen atom. It has a molecular formula of HN₅. Its SMILES structure is n1n[nH]nn1. Although strictly speaking a homocyclic, inorganic compound, pentazole has historically been classed as the last in a series of heterocyclic azole compounds containing one to five nitrogen atoms.This set contains pyrrole, imidazole, pyrazole, triazoles, tetrazoles, and pentazole. One can consider pentazole to be at the interface between inorganic and organic chemistry."

"Substituted analogs of pentazole are collectively known as pentazoles. As a class, they are unstable and often highly explosive compounds. The first pentazole synthesized was phenyl pentazole, where the pentazole ring is highly stabilized by conjugation with the phenyl ring. The derivative 4-dimethylaminophenylpentazole is among the most stable pentazole compounds known, although it still decomposes at temperatures over 50°C. It is known that electron-donating groups stabilize aryl pentazole compounds."