La₆Ba₃[Si₁₇N₂₉O₂]Cl—An Oxonitridosilicate Chloride with Exceptional Structural Motifs

Abstract

The oxonitridosilicate chloride La6Ba3[Si17N29O2]Cl was synthesized by a high-temperature reaction in a radiofrequency furnace starting from LaCl3, BaH2, and the ammonolysis product of Si2Cl6. Diffraction data of a micrometer-sized single crystal were obtained using microfocused synchrotron radiation at beamline ID11 of the ESRF. EDX measurements on the same crystal confirm the chemical composition. The crystal structure [space group P63/m (no. 176), a = 9.8117(14), c = 19.286(6) Å, Z = 2] contains an unprecedented interrupted three-dimensional network of vertex-sharing SiN4 and SiN3O tetrahedra. The SiN4 tetrahedra form dreier rings. Twenty of the latter condense in a way that the Si atoms form icosahedra. Each icosahedron is connected to others via six SiN4 tetrahedra that are part of dreier rings and via six Q(3)-type SiN3O tetrahedra. Rietveld refinements confirm that the final product contains only a small amount of impurities. Lattice energy (MAPLE) and bond-valence sum (BVS) calculations show that the structure is electrostatically well balanced. Infrared spectroscopy confirms the absence of N-H bonds.

Oxonitridosilicate Oxides RE26Ba6[Si22O19N36]O16:Eu2+ (RE = Y, Tb) with a Unique Layered Structure and Orange-Red Luminescence for RE = Y

“…In order to obtain further silicates with divalent and trivalent cations, new explorative synthesis routes are desired. Recently, reactions of AE metal hydrides and RE metal halides yielded a couple of novel compounds. ,, Besides their intriguing structural chemistry, the obtained AE – RE –Si–O–N compounds are auspicious host lattices for Eu 2+ and Ce 3+ doping. In this context, the recently reported phosphors La 3 BaSi 5 N 9 O 2 :Ce 3+ and Lu 4 Ba 2 ­[Si 9 ON 16 ]­O:Eu 2+ stand out.…”

Ba1.63La7.39Si11N23Cl0.42:Ce3+ – A Nitridosilicate Chloride with a Zeolite‐Like Structure

“…the product of the ammonolysis of Si 2 Cl 6 , turned out to be a promising precursor that offers another stoichiometric proportion of Si and N and another oxidation state of Si as in "Si(NH) 2 ", which opens the door to further nitridosilicates. [23] Still, high-temperature syntheses often result in microcrystalline and inhomogeneous samples. Structure solution and refinement by conventional single crystal or powder methods is hardly possible in such cases.…”

“…Besides, “Si 2 (NH) 3 · 6NH 4 Cl”, i.e. the product of the ammonolysis of Si 2 Cl 6 , turned out to be a promising precursor that offers another stoichiometric proportion of Si and N and another oxidation state of Si as in “Si(NH) 2 ”, which opens the door to further nitridosilicates 23…”

LiCa4Si4N8F and LiSr4Si4N8F: Nitridosilicate Fluorides with a BCT‐Zeolite‐Type Network Structure

“…This shows the broad flexibility of this nitride network to embed diverse sorts of atoms or units. Furthermore, the title compounds are additional examples of the benefits of the chosen metathesis route, which was initially established for a variety of lanthanum (oxo)nitridosilicates , , . This reaction mechanism led, on the one hand, to the first compounds in the system Li‐ EA ‐Si‐N‐F ( EA = Ca, Sr).…”