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Ammeline is a simple, readily available, molecular compound, which has been known for nearly 200 years. Despite that, no proper structural characterization of ammeline has been conducted so far. For this reason, the prevalent tautomeric form of ammeline in the solid remained unknown to this date. In the course of this study, its crystal structure was finally established by single‐crystal X‐ray diffraction. In this structure, ammeline is exclusively found as its 4,6‐diamino‐1,3,5‐triazin‐2(1H)‐one tautomer and adopts layered structure with an exceptionally high hydrogen bond density. Ammeline shows an interesting amphoteric behavior. Therefore, the synthesis and structural characterization of some of its salts were carried out to investigate the influence of the protonation degree on its molecular structure. In particular, the crystal structure of silver ammelinate monohydrate was solved as the first reported structure containing deprotonated ammeline. Moreover, the crystal structures of three different modifications of ammelinium perchlorate were elucidated and the transformation conditions between them were studied. Lastly, the crystal structure of ammelinediium diperchlorate monohydrate, containing unprecedented doubly protonated ammeline, was determined. The products' thermal behavior was studied by differential thermal analysis and thermogravimetric analysis. The perchlorate salts were additionally examined for their potential as insensitive high‐energy‐density materials. [ABSTRACT FROM AUTHOR]

Although beryllium and its compounds show outstanding properties, owing to its toxic potential and extreme reaction conditions the chemistry of Be under high‐pressure conditions has only been investigated sparsely. Herein, we report on the highly condensed wurtzite‐type Be2PN3, which was synthesized from Be3N2 and P3N5 in a high‐pressure high‐temperature approach at 9 GPa and 1500 °C. It is the missing member in the row of formula type M2PN3 (M = Mg, Zn). The structure was elucidated by powder X‐ray diffraction (PXRD), revealing that Be2PN3 is a double nitride, rather than a nitridophosphate. The structural model was further corroborated by 9Be and 31P solid‐state nuclear magnetic resonance (NMR) spectroscopy. We present 9Be NMR data for tetrahedral nitride coordination for the first time. Infrared and energy‐dispersive X‐ray spectroscopy (FTIR and EDX), as well as temperature dependent PXRD complement the analytical characterization. Density functional theory (DFT) calculations reveal super‐incompressible behavior and the remarkable hardness of this low‐density material. The formation of Be2PN3 through a high‐pressure high‐temperature approach expands the synthetic access to Be‐containing compounds and may open access to various multinary beryllium nitrides. [ABSTRACT FROM AUTHOR]

Tetrahedron‐based nitrides offer a wide range of properties and applications. Highly condensed nitridophosphates are examples of nitrides that exhibit fascinating luminescence properties when doped with Eu2+, making them appealing for industrial applications. Here, we present the first nitridomagnesophosphate solid solution series Ba3−xSrx[Mg2P10N20] : Eu2+ (x=0–3), synthesized by a high‐pressure high‐temperature approach using the multianvil technique (3 GPa, 1400 °C). Starting from the binary nitrides P3N5 and Mg3N2 and the respective alkaline earth azides, we incorporate Mg into the P/N framework to increase the degree of condensation κ to 0.6, the highest observed value for alkaline earth nitridophosphates. The crystal structure was elucidated by single‐crystal X‐ray diffraction, powder X‐ray diffraction, energy‐dispersive X‐ray spectroscopy (EDX), and solid‐state NMR. DFT calculations were performed on the title compounds and other related highly condensed nitridophosphates to investigate the influence of Mg in the P/N network. Eu2+‐doped samples of the solid solution series show a tunable narrow‐band emission from cyan to green (492–515 nm), which is attributed to the preferred doping of a single crystallographic site. Experimental confirmation of this assumption was provided by overdoping experiments and STEM‐HAADF studies on the series as well on the stoichiometric compound Ba2Eu[Mg2P10N20] with additional atomic resolution energy‐dispersive X‐ray spectroscopy (EDX) mapping. [ABSTRACT FROM AUTHOR]

Although beryllium and its compounds show outstanding properties, owing to its toxic potential and extreme reaction conditions the chemistry of Be under high‐pressure conditions has only been investigated sparsely. Herein, we report on the highly condensed wurtzite‐type Be2PN3, which was synthesized from Be3N2 and P3N5 in a high‐pressure high‐temperature approach at 9 GPa and 1500 °C. It is the missing member in the row of formula type M2PN3 (M = Mg, Zn). The structure was elucidated by powder X‐ray diffraction (PXRD), revealing that Be2PN3 is a double nitride, rather than a nitridophosphate. The structural model was further corroborated by 9Be and 31P solid‐state nuclear magnetic resonance (NMR) spectroscopy. We present 9Be NMR data for tetrahedral nitride coordination for the first time. Infrared and energy‐dispersive X‐ray spectroscopy (FTIR and EDX), as well as temperature dependent PXRD complement the analytical characterization. Density functional theory (DFT) calculations reveal super‐incompressible behavior and the remarkable hardness of this low‐density material. The formation of Be2PN3 through a high‐pressure high‐temperature approach expands the synthetic access to Be‐containing compounds and may open access to various multinary beryllium nitrides. [ABSTRACT FROM AUTHOR]