Pentazole,the last discovered structural unit of the azole series of compounds,has received considerable attention from research-ers[1,2].The pentacyclic structure that is formed by the high-energy N-N and N=N bonds between the five nitrogen atoms in pentazole possesses aromaticity,which provides good thermal sta-bility[3].Consequently,most metallic and non-metallic salts syn-thesized from pentazole have decomposition temperatures exceeding 100 ℃.Moreover,pentazole is the only all-nitrogen structure other than N2 and N3-that is stable at room temperature[4-7].In contrast,the five-nitrogen-atom chain structure of N5+,which was first synthesized in 1999[6,8],has a decomposition temperature below 0 ℃ owing to a lack of aromaticity(Fig.1)[6,7].