Pentazolate Anion: A Rare and Preferred Five-Membered Ligand for Constructing Pentasil-Zeolite Topology Architectures.

As the fourth full-nitrogen structure, the pentazolate anion (cyclo-N 5 - ) was highly coveted for decades. In 2017, the first air-stable non-metal pentazolate salt, (N 5 ) 6 (H 3 O) 3 (NH 4 ) 4 Cl, was obtained, representing a milestone in this field. As the latest member of the azole family, cyclo-N 5 - is comprised of five nitrogen atoms. Although significant attention has been paid to the potential of cyclo-N 5 - as an energetic material, its poor thermostability hinders any practical application. However, the unique ring structure and multiple coordination capability of cyclo-N 5 - provide a platform for the fabrication of various structures, among which pentasil-zeolite topologies are the most intriguing. In addition, the introduction of structure-directing auxiliaries enables the self-assembly of diverse topological architectures, potentially imparting cyclo-N 5 - with the potential to impact wide-ranging areas of coordination chemistry and topology. In this minireview, different pentasil-zeolite topologies based on metal-pentazolate frameworks are evaluated. To date, three zeolitic and zeolite-like topologies have been reported, namely the melanophlogite (MEP), chibaite (MTN), and unj topologies. The MEP topology consists of two nanocages, Na 20 N 60 and Na 24 N 60 , whereas the MTN topology contains Na 20 N 60 and Na 28 N 80 nanocages. Furthermore, the unj topology features multiple homochiral channels consisting of two helical chains. Various possible strategies for obtaining additional pentasil-zeolite topologies are also discussed.