Darstellung und Kristallstrukturen von Li_4−2xSr_2+xB₁₀S₁₉ (x ≈ 0,27) und Na₆B₁₀S₁₈. Zwei neue Thioborate mit hochpolymeren Makrotetraeder‐Netzwerken

Abstract

Li4−2xSr2+xB10S19 (x ≈ 0,27) und Na6B10S18 wurden aus der Summenformel entsprechenden Mengen Strontiumsulfid und Lithiumsulfid (Natriumsulfid), amorphem Bor und Schwefel bei 700°C in graphitierten Quarzglasampullen dargestellt. Li4−2xSr2+xB10S19 (x ≈ 0,27) kristallisiert monoklin in der Raumgruppe P21/c mit a = 10,919(2) Å, b = 13,590(3) Å, c = 16,423(4) Å, und β = 90,48(2)°, Na6B10S18 tetragonal in der Raumgruppe I41/acd mit a = 14,415(3) Å, c = 26,137(4) Å. Beide Strukturen enthalten supertetraedrische B10S20‐Einheiten, die über Tetraederecken zu einem dreidimensionalen polymeren anionischen Raumnetzwerk im Falle des Na6B10S18 bzw. zu eindimensionalen Anionen‐Ketten im Falle des Li4−2xSr2+xB10S19 (x ≈ 0,27) verbunden sind. Alle Boratome haben tetraedrische BS4‐Koordination (die BS‐Abstände variieren von 1,879(5) Å bis 1,951(5) Å (1,875(10) Å bis 1,987(9) Å)). Die Strontium‐ und Lithium‐(Natrium‐)Kationen befinden sich in ausgedehnten Kanälen innerhalb des Anionengerüsts.

Structure determination of low-alkali-content Na2S+B2S3 glasses using neutron and synchrotron X-ray diffraction

“…This may be due to the conversion from trigonally coordinated boron units to tetrahedrally coordinated boron units. The B-S distance in tetrahedrally bonded boron groups is found to vary between 1.879 Å and 1.951 Å [28]. Hence, the observed shift in the first PDF peak is consistent with the formation of tetrahedral borons in these low alkali glasses.…”

Syntheses, Crystal Structures, and Properties of the Novel Thioborates KBa4(BS3)3 and K4Ba11(BS3)8S

“…Binary boron sulfides and selenides [1, 3±5] [8, 12±14] which are characteristic structural features in chalcogenoborates of alkali and alkaline earth metals. It is well known that in addition to large cations such as strontium and barium, smaller alkali ions, especially lithium, can be incorporated in thioborate structures [7,8,15]. This is of special importance for the physical properties of these compounds, e. g. for the ionic conductivity observed in some lithium thioborates [16,17].…”

“…In this context, more detailed knowledge on the possible substitution of lithium by its heavier homologues in the aformentioned compounds as well as on the possible insertion of alkali metals in larger framework structures is necessary. Such networks are also found in several thioborate structures containing lithium, sodium or even silver cations [15,19]. As systematic studies are hitherto only available for a few selected ternary and quaternary phases, further investigations are underway, i. e. several projects in our group are focussing on sodium and potassium containing chalcogenoborates and their physical properties.…”

Lone‐Pair Interfaces That Divide Inorganic Materials into Ionic and Covalent Parts

“…The Cu-Cl arrangement is simple but remarkable: CuCl 4 tetrahedra share Cl vertices to form T3 supertetrahedral [Cu 10 Cl 20 ] 10À units, much akin to the borosulfate and boroselenate T3 supertetrahedra reported by Krebs et al [8][9][10] Recent research has focused on nanoclusters with large Tn supertetrahedral units, as they have a potential to create novel low-density nanoporous crystalline solids with many interesting properties. Those studies concern chalcogenide clusters built of supertetrahedra of type T4 and T5.…”