Fully Active Nitrogen Energetic Chains Mg₂(N₅)₂N₂[Mg₂(N₅)₂N₂]_n under Ambient Conditions

Pentazolate anion (cyclo-N₅⁻) is a high energy density unit that has been synthesized. However, how to make cyclo-N₅⁻ complexes stable under ambient condition, without the presence of nonenergetic components, such as H₃O⁺ and NH₄⁺, has always been a challenge. In this work, a fully active nitrogen energetic chain Mg₂(N₅)₂N₂[Mg₂(N₅)₂N₂]_n (denoted as ANEC_n, n ≥ 1) is reported, which has high nitrogen content up to 78%. More importantly, first-principles calculations and molecular dynamics simulations confirm the stability of this structure without external supports. Further electronic structure analysis indicates that the charge transfer from Mg to cyclo-N₅⁻ leads to strong covalent bonds, which promotes the stability of cyclo-N₅⁻ in the chain structures. This finding can contribute to rational design and synthesis of novel high-energy density materials.