Novel All‐Nitrogen Molecular Crystals of Aromatic N₁₀

Abstract

Nitrogen has unique bonding ability to form single, double, and triple bonds, similar to that of carbon. However, a molecular crystal formed by an aromatic polynitrogen similar to a carbon system has not been found yet. Herein, a new form of stable all‐nitrogen molecular crystals consisting of only bispentazole N10 molecules with exceedingly high energy density is predicted. The crystal structures and the conformation of N10 molecules are strongly correlated, both depending on the applied external pressure. These molecular crystals can be recovered upon the release of the pressure. The first‐principles molecular dynamics simulations reveal that these all‐nitrogen materials decompose at temperatures much higher than room temperature. The decompositions always start from breaking off N2 molecules from the nitrogen ring and can release a large amount of energy. These new polynitrogens are aromatic and are more stable than all the other polynitrogen crystals reported previously, providing a new green strategy to get all‐nitrogen, nonpolluting high energy density materials without introducing any metal or other guest stabilizer.

Solid Nitrogen and Nitrogen‐Rich Compounds as High‐Energy‐Density Materials

“…Of course, other oligomers are also possible (N 10 , N 60 ) and have been examined. [48,49] The limit of oligomers, the 1D infinite chain, was predicted to form as well. [14,15,50] In chainlike structure, nitrogen atoms are connected by alternating single and double bonds, and therefore its region of stability is predicted to be after molecular N 2 but before that of cg nitrogen.…”

Materials by design at high pressures

“…106 Many other stable or metastable polymeric nitrogen phases at high pressures have also been predicted by CSP methods. 26,[107][108][109][110][111][112][113][114] Among the most-energetically stable phases, a phase sequence of cg-N / orthorhombic LP-Pba2 (188 GPa) 26 / bcc I-43m (263 GPa) 111 / orthorhombic Cmca (2200 GPa) 112 / tetragonal P4/nbm (2500 GPa) 112 was suggested (Fig. 5b-d).…”

Novel All-Nitrogen Molecular Crystals Composed of Tetragonal N4 Molecules

“…Subsequently, Michael et al showed that N crystals are dynamically metastable at room temperature by metadynamic simulations, but dissociate to N molecules above 700 K [ 22 ]. Metastable all-nitrogen molecular crystals consisting of N molecules were recently reported by Shijie Liu et al [ 23 ] The structures of these molecular crystals are affected by external pressure, and their decomposition temperature is much higher than room temperature. There is experimental evidence for the isolation of Td-N [ 18 ], although the conclusive assignment of spectral features requires further experimentation.…”