ZnH2P4N8: Case Study on Topochemical Imidonitridophosphate High-Pressure Synthesis.

Nitridophosphates are subject of current research, as they have a broad spectrum of properties and potential applications, such as ion conductors or luminescent materials. Yet, the subclass of imidonitridophosphates has been studied less extensively. The primary reason is that the controlled N-H functionalization of nitridophosphates is not straight forward, making targeted synthesis more challenging. Inspired by the high-pressure (HP) post-synthetic modification of nitridophosphates, we present the topochemical HP deprotonation of phosphorus nitride imides using the high-pressure polymorph ß-PN(NH) as an example. Additional incorporation of Zn2+ results in the first quaternary transition metal imidonitridophosphate ZnH2P4N8. The crystal structure was elucidated by single-crystal X-ray diffraction (SCXRD), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (PXRD) and solid-state magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR). In addition, the presence of H as part of an imide group was confirmed by IR spectroscopy. The potential of this defunctionalization approach for controlling the N-H content is demonstrated by the preparation of partially deprotonated intermediates ZnxH4-2xP4N8 (x ≈  0.5, 0.85). This topochemical high-pressure reaction represents a promising way to prepare, control and manipulate new imide-based materials without altering their overall anionic framework.

Trigonal Planar [PN3]4- Anion in the Nitridophosphate Oxide Ba3[PN3]O.

Nitridophosphates, with their primary structural motif of isolated or condensed PN4 tetrahedra, meet many requirements for high performance materials. Their properties are associated with their structural diversity, which is mainly limited by this specific building block. Herein, we present the alkaline earth metal nitridophosphate oxide Ba3[PN3]O featuring a trigonal planar [PN3]4- anion. Ba3[PN3]O was obtained using a hot isostatic press by medium-pressure high-temperature synthesis (MP/HT) at 200 MPa and 880 °C. The crystal structure was solved and refined from single-crystal X-ray diffraction data in space group R 3 ‾ ${\bar 3}$ c (no. 167) and confirmed by SEM-EDX, magic angle spinning (MAS) NMR, vibrational spectroscopy (Raman, IR) and low-cost crystallographic calculations (LCC). MP/HT synthesis reveals great potential by extending the structural chemistry of P to include trigonal planar [PN3]4- motifs.

Rivalry under Pressure: The Coexistence of Ambient-Pressure Motifs and Close-Packing in Silicon Phosphorus Nitride Imide SiP2 N4 NH.

Non-metal nitrides such as BN, Si3 N4 , and P3 N5 meet numerous demands on high-performance materials, and their high-pressure polymorphs exhibit outstanding mechanical properties. Herein, we present the silicon phosphorus nitride imide SiP2 N4 NH featuring sixfold coordinated Si. Using the multi-anvil technique, SiP2 N4 NH was obtained by high-pressure high-temperature synthesis at 8 GPa and 1100 °C with in situ formed HCl acting as a mineralizer. Its structure was elucidated by a combination of single-crystal X-ray diffraction and solid-state NMR measurements. Moreover, SiP2 N4 NH was characterized by energy-dispersive X-ray spectroscopy and (temperature-dependent) powder X-ray diffraction. The highly condensed Si/P/N framework features PN4 tetrahedra as well as the rare motif of SiN6 octahedra, and is discussed in the context of ambient-pressure motifs competing with close-packing of nitride anions, representing a missing link in the high-pressure chemistry of non-metal nitrides.

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.