High-Pressure Synthesis of K4N6 with All Nitrogen Atoms Forming Aromatic Hexazine [N6]4– Anions

Realizing compounds entirely composed of aromatic hexazine N6 rings with high stability is a long-term challenge. Existing high-pressure synthesized compounds contain a maximum of 5.36% N atoms, forming aromatic [N6]4– rings. We predict that all N atoms contribute to aromatic [N6]4– rings in K4N6, which become stable at 60 GPa and can stably exist up to 600 K at 0 GPa. Furthermore, K and KN3 are suggested as precursors for the synthesis of K4N6. Following this approach, based on the diamond anvil cell, K4N6 with 100% nitrogen atoms forming aromatic hexazine [N6]4– rings is synthesized at 45 GPa after laser heating and identified by synchrotron X-ray diffraction and Raman spectroscopy. Our results bring us closer to achieving aromatic N6 rings at ambient condition.