High-Pressure Synthesis of a Nitrogen-Rich Inclusion Compound $\mathrm{ReN_{8} ⋅ x N_{2}}$ with Conjugated Polymeric Nitrogen Chains

Abstract

A nitrogen‐rich compound, $\mathrm{ReN_{8} ⋅ x N_{2}}$, was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser‐heated diamond anvil cell. Single‐crystal X‐ray diffraction revealed that the crystal structure, which is based on the ReN8 framework, has rectangular‐shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100 GPa, $\mathrm{ReN_{8} ⋅ x N_{2}}$ is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains $\mathrm{[−N=N−]_∞}$ that constitute the framework have not been previously observed in any compound. Ab initio calculations on $\mathrm{ReN_{8} ⋅ x N_{2}}$ provide strong support for the experimental results and conclusions