Crystal chemical design of novel high energy density polynitrides

The high-pressure chemistry of nitrogen and nitrogen-rich compounds have been in a focus of many studies in the recent years due to both fundamental and practical interest and due to the improvement of high-pressure synthetic and characterization techniques. Polynitrogen compounds are usually considered as potential high energy density materials due to the remarkable difference in the energies of single, double and triple N-N bonds. In the present work we have systematically studied reactions between transition metals and nitrogen at pressures up to 130 GPa in laser-heated diamond anvil cells. Hf, W, Re and Os react with nitrogen forming porous metal-inorganic frameworks Hf₂N₁₁, WN₁₀, ReN₁₀ and Os₅N₃₄ of various topology [1,2]. The frameworks are built of metals interconnected via polymeric nitrogen linkers, while the pores are filled with dinitrogen molecules N₂. Lighter transition metals form non-porous polynitrides featuring polymeric nitrogen chains. In this contribution we will discuss novel synthetic routes to energetic polynitrogen compounds and crystal-chemical rules governing their formation.

[1] M. Bykov, et al. Angew. Chemie Int. Ed. 59, 10321 (2020)
[2] M. Bykov, et al. Angew. Chemie Int. Ed. 57, 9048 (2018)