United in Nitride: The Highly Condensed Boron Phosphorus Nitride BP₃ N₆

Owing to intriguing materials properties non-metal nitrides are of special interest for both, solid-state chemistry and materials science. Mixed ternary non-metal nitrides, however, have only been sparsely investigated, as preparative chemistry lacks a systematic access, yet. Herein, we report on the highly condensed boron phosphorus nitride BP₃ N₆ , which was synthesized from (PNCl₂ )₃ , NH₄ N₃ and h-BN in a high-pressure high-temperature reaction. By increasing partial pressure of HCl during synthesis using NH₄ Cl, single-crystals of BP₃ N₆ up to 80 μm in length were obtained. The unprecedented framework-type structure determined by single-crystal XRD blends structural motifs of both, α-P₃ N₅ and c-BN, rendering BP₃ N₆ a double nitride. The compound was further investigated by Rietveld refinement, EDX, temperature-dependent PXRD, FTIR and solid-state NMR spectroscopy. The formation of BP₃ N₆ through use of reactive precursors exemplifies an innovative access to mixed non-metal nitrides.