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Sr4Ba3(BO3)3.83H2.5, as the second compound to combine borate and hydride ions, has been synthesized by a mechanochemical synthesis route. The structure has been elucidated by synchrotron X‐ray and neutron diffraction and determined to crystallize in the non‐centrosymmetric space group P63mc (186) with the cell parameters a=10.87762(15) Å and c=6.98061(11) Å. A detailed investigation of the compound by vibrational spectroscopy in combination with Density Functional Theory calculations reveals the disordered nature of the structure and proves the presence of both borate and hydride ions. Electronic band structure calculations predict a large band gap of 7.1 eV. Hydride states are predicted at the topmost valence band, which agrees well with earlier reported heteroanionic hydrides. We hereby were able to successfully apply previously synthetic and analytical schemes to introduce another member of the rare compounds that contain complex oxoanions simultaneously with hydride ions. [ABSTRACT FROM AUTHOR]

Sr4Ba3(BO3)3.83H2.5, as the second compound to combine borate and hydride ions, has been synthesized by a mechanochemical synthesis route. The structure has been elucidated by synchrotron X‐ray and neutron diffraction and determined to crystallize in the non‐centrosymmetric space group P63mc (186) with the cell parameters a=10.87762(15) Å and c=6.98061(11) Å. A detailed investigation of the compound by vibrational spectroscopy in combination with Density Functional Theory calculations reveals the disordered nature of the structure and proves the presence of both borate and hydride ions. Electronic band structure calculations predict a large band gap of 7.1 eV. Hydride states are predicted at the topmost valence band, which agrees well with earlier reported heteroanionic hydrides. We hereby were able to successfully apply previously synthetic and analytical schemes to introduce another member of the rare compounds that contain complex oxoanions simultaneously with hydride ions. [ABSTRACT FROM AUTHOR]

As the first europium(II) hydride oxide iodide, dark red single crystals of Eu5H2O2I4 could be synthesized from oxygen-contaminated mixtures of EuH2 and EuI2. Its orthorhombic crystal structure (a = 1636.97(9) pm, b = 1369.54(8) pm, c = 604.36(4) pm, Z = 4) was determined via single-crystal X-ray diffraction in the space group Cmcm. Anion-centred tetrahedra [HEu4]7+ and [OEu4]6+ serve as central building blocks interconnected via common edges to infinite ribbons parallel to the c axis. These ribbons consist of four trans-edge connected (Eu2+)4 tetrahedra as repetition unit, two H−-centred ones in the inner part, and two O2−-centred ones representing the outer sides. They are positively charged, according to ∞ 1 {[Eu5H2O2]4+}, to become interconnected and charge-balanced by iodide anions. Upon excitation with UV light, the compound shows blue–green luminescence with the shortest Eu2+ emission wavelength ever observed for a hydride derivative, peaking at 463 nm. The magnetic susceptibility of Eu5H2O2I4 follows the Curie-Weiss law down to 100 K, and exhibits a ferromagnetic ordering transition at about 10 K. [ABSTRACT FROM AUTHOR]

The article "Cover Feature: The Non-Centrosymmetric Borate Hydride Sr4Ba3(BO3)3.83H2.5" in Chemistry - A European Journal discusses the use of neutron diffraction to determine the chemical composition of the compound Sr4Ba3(BO3)3.83H2.5. The research reveals the presence of a unique complex [BO3H]4− anion within the structure. Authors A. Mutschke and co‐workers provide further details in their Research Article (DOI: 10.1002/chem.202403048). [Extracted from the article]

With increasing interest in mixed‐anionic hydrides, a number of interesting properties have been reported. Here, the structural and optical properties of (Eu2+‐doped) MCaH3–MCaF3 (M = Rb, Cs) are investigated. For M = Rb, a complete hydride–fluoride solid solution series is found and for M = Cs, the known solid solution series (0 ≤ x ≤ 1.70) can be extended to x = 3. In case of Cs, a very bright luminescence emission is observed in Eu2+‐doped samples, whereas the luminescence is fairly weak in Rb based compounds. With increasing hydride content, a shift of the emission color from cyan‐green to red can be observed. In contrast to earlier reports for mixed fluoride–hydride host, the redshift is not a gradual shift of a single broad emission band, but the appearance of new narrow emission bands on the low energy side, which are assigned to the occupation of sites with higher hydride content. Consequently, this finding represents the first example in a mixed anionic hydride with a site‐sensitive emission for sites with locally varying hydride content in the first coordination sphere and may serve as a general example for emission color tuning taking advantage of mixed‐anionic compounds. [ABSTRACT FROM AUTHOR]

The unprecedented borate hydride Sr5(BO3)3H and deuteride Sr5(11BO3)3D crystallizing in an apatite‐related structure are reported. Despite the presence of hydride anions, the compound decomposes only slowly in air. Doped with Eu2+, it shows broad‐band orange‐red emission under violet excitation owing to the 4f65d–4f7 transition of Eu2+. The observed 1H NMR chemical shift is in good agreement with previously reported 1H chemical shifts of ionic metal hydrides as well as with quantum chemical calculations and very different from 1H chemical shifts usually found for hydroxide ions in similar materials. FTIR and Raman spectroscopy of different samples containing 1H, 2H, natB, and 11B combined with calculations unambiguously prove the absence of hydroxide ions and the sole incorporation of hydride ions into the borate. The orange‐red emission obtained by doping with Eu2+ shows that the new compound class might be a promising host material for optical applications. [ABSTRACT FROM AUTHOR]

The engineering of covalency and crystal field is a key point for the control of the 5d energy level of Eu2+. The hydride ion exhibits strong covalency, which results in a large 5d energy shift by the nephelauxetic effect compared to their fluoride analogues. In this study, the Eu2+-doped K2MgH4 Ruddlesden–Popper (n = 1) perovskite was prepared and its optical properties were investigated. Red luminescence due to the 4f65d1 → 4f7 transition was observed at 670 nm by UV excitation of the K2MgH4:Eu2+ sample. Compared with yellow Eu2+-luminescence at 565 nm of the KMgH3 cubic perovskite, which has almost the same chemical composition as K2MgH4, the additional red-shift of the luminescence in K2MgH4:Eu2+ is caused by the strong crystal field splitting in the unique 9-fold coordinated site in addition to the large nephelauxetic effect by hydride ions. Using a hydride model system that allows for a clear distinction between crystal field splitting and nephelauxetic effect, we successfully demonstrated the design concept for the 5d energy shifting by covalency and crystal field in Eu2+-doped K2MgH4. Also, the thermal quenching process of K2MgH4:Eu2+ by the ionization process was discussed in comparison to KMgH3:Eu2+ on the basis of the energy diagram. [ABSTRACT FROM AUTHOR]

The apatite family is a mineral class that also contains the biologically very important hydroxyapatite. Here, we are reporting on the synthesis and characterization of a fully hydride‐substituted strontium apatite, which could be obtained via mechanochemical synthesis and subsequent annealing treatment. The full substitution by hydride anions is proven by various methods, such as neutron powder diffraction of a deuterated sample Sr5(PO4)3D, as well 1H MAS solid state NMR combined with quantum chemical calculations, vibrational spectroscopy and elemental analysis. The present work expands the apatite family from the known halide and hydroxide apatites to the fully hydride‐anion‐substituted variant and is expected to open up a new field of materials containing coexistent phosphate and hydride anions. [ABSTRACT FROM AUTHOR]

The optical properties of rare earth ions in different inorganic host materials, for instance oxides, silicates, borates, or nitrides, have been used in applications for many years, from color TV to fluorescent tubes, lasers, or pc‐LEDs. However, rare earth metal ion‐doped hydrides have not really been considered as host lattices and up to now only been studied in a relatively small number of investigations. Yet, for certain metal hydrides these studies, e.g., allowed the determination of the crystal field strength and nephelauxetic effect of the hydride anion using the Eu2+ 5d excited state. In air‐sensitive hydrides, the use may be restricted to fundamental studies and local probes. But recently more and more air‐stable mixed anionic hydrides have been discovered, which may serve as hosts. This short review summarizes the synthesis and characterization of rare earth metal ion‐doped hydrides reported so far. [ABSTRACT FROM AUTHOR]

In the search for novel mixed anionic hydrides, simple and sensitive detection methods can be useful and local probes lead to a better understanding of the materials. In our present study, we show that 5d–4f lanthanide luminescence can serve as a local sensor to verify the presence of hydride and potentially estimate the hydride content. As a model system, the Eu2+-doped hydride fluoride solid solution series of MMgDxF3−x (MMgHxF3−x) with M = K, Rb is used, which were prepared and characterized by a combined X-ray and neutron diffraction approach. At room temperature, the compounds with M = Rb crystallize in a hexagonal perovskite-type structure and those with M = K crystallize in a normal cubic perovskite structure. Their lattice parameters follow Vegard's law. We also reinvestigated the structure and anion distribution in KMgD2F. Bright yellow emission in RbMgH3:Eu2+ is observed for the first time and for both M, the hydride fluoride compounds show Eu2+ emission energies between those of the pure hydrides and fluorides, which can be used for calibration and fast idendification of the hydride content, especially in the region of low hydride content. [ABSTRACT FROM AUTHOR]

Structural, electronic and vibrational spectroscopic investigations were performed for the solid solution NaP7-xAsx up to x = 3.5 featuring a helical polypnictide substructure. Depending on the As content the LiP7 (for x = 0 to 0.8 and 2.5 to 3.5) or KP15 (x = 1.0 to 2.4) structure type is realized up to an maximum As content of x = 3.5. The crystal structures of two selected phases were determined and the distribution of As in the polyanionic substructure was determined. The full solid solution up to x = 7 was subject to a quantum chemical DFT analysis in order to get insights into the stabilities and phase formation tendencies. Van der Waals interactions between the structure subunits were estimated and first principle investigations towards a delamination and nano structuring of NaP7-xAsx crystals into one-dimensional semiconductors were performeda [ABSTRACT FROM AUTHOR]

Sr 4 Ba 3 (BO 3 ) 3.83 H 2.5 , as the second compound to combine borate and hydride ions, has been synthesized by a mechanochemical synthesis route. The structure has been elucidated by synchrotron X-ray and neutron diffraction and determined to crystallize in the non-centrosymmetric space group P6 3 mc (186) with the cell parameters a=10.87762(15) Å and c=6.98061(11) Å. A detailed investigation of the compound by vibrational spectroscopy in combination with Density Functional Theory calculations reveals the disordered nature of the structure and proves the presence of both borate and hydride ions. Electronic band structure calculations predict a large band gap of 7.1 eV. Hydride states are predicted at the topmost valence band, which agrees well with earlier reported heteroanionic hydrides. We hereby were able to successfully apply previously synthetic and analytical schemes to introduce another member of the rare compounds that contain complex oxoanions simultaneously with hydride ions., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

The unprecedented borate hydride Sr 5 (BO 3 ) 3 H and deuteride Sr 5 ( 11 BO 3 ) 3 D crystallizing in an apatite-related structure are reported. Despite the presence of hydride anions, the compound decomposes only slowly in air. Doped with Eu 2+ , it shows broad-band orange-red emission under violet excitation owing to the 4f 6 5d-4f 7 transition of Eu 2+ . The observed 1 H NMR chemical shift is in good agreement with previously reported 1 H chemical shifts of ionic metal hydrides as well as with quantum chemical calculations and very different from 1 H chemical shifts usually found for hydroxide ions in similar materials. FTIR and Raman spectroscopy of different samples containing 1 H, 2 H, nat B, and 11 B combined with calculations unambiguously prove the absence of hydroxide ions and the sole incorporation of hydride ions into the borate. The orange-red emission obtained by doping with Eu 2+ shows that the new compound class might be a promising host material for optical applications., (© 2020 The Authors. Published by Wiley-VCH GmbH.)