Stabilization of the Pentazolate Anion in a Zeolitic Architecture with Na₂₀N₆₀ and Na₂₄N₆₀ Nanocages

The experimental detection and synthesis of pentazole (HN₅) and its anion (cyclo-N₅⁻) have been actively pursued for the past hundred years. The synthesis of an aesthetic three-dimensional metal–pentazolate framework (denoted as MPF-1) is presented. It consists of sodium ions and cyclo-N₅⁻ anions in which the isolated cyclo-N₅⁻ anions are preternaturally stabilized in this inorganic open framework featuring two types of nanocages (Na₂₀N₆₀ and Na₂₄N₆₀) through strong metal coordination bonds. The compound MPF-1 is indefinitely stable at room temperature and exhibits high thermal stability relative to the reported cyclo-N₅⁻ salts. This finding offers a new approach to create metal–pentazolate frameworks (MPFs) and enables the future exploration of interesting pentazole chemistry and also related functional materials.