Selenogermanate aus wäßriger Lösung: Darstellung und Struktur von Na4Ge2Se6 · 16 H2O

Selenogermanates from Aqueous Solution: Preparation and Structure of Na₄Ge₂Se₆ · 16 H₂O Selenogermanates(IV) are prepared from aqueous solutions by reaction of alkali selenides with GeSe₂. Na₄Ge₂Se₆ · 16 H₂O, being obtained from stoichiometric 1:1 quantities, is characterized by a complete X-ray structure analysis and by vibrational spectra. The compound is monoclinic (P2₁/c) with a = 9.894(4), b = 11.781(5), c = 12.225(6) Å, β = 92.90(4)°, Z = 2. It contains isolated Ge₂Se₆^4? anions consisting of two edge-sharing tetrahedra [Ge? Se 2.303(2)–2.419(2) Å] which are in contact to the hydrated octahedral [Na(H₂O)₆]⁺ ions through Se ? H? O bridges within an extensive hydrogen bridge system. Raman-active vibrations are observed at 306, 294, 207, 139, and 121 cm^?1. Adamantane-like Ge₄Se₁₀^4? can be prepared in a similar way as Ge₂Se₆^4? if a 1:2 molar ratio of alkali selenide to GeSe₂ is employed.     

New Selenidogermanates with Transition-Metal Complexes as Counterions: Solvothermal Synthesis, Crystal Structures, and Properties of [Mn(en)3]2Ge2Se6 and [Fe(dien)2]2Ge2Se6

Summary. New selenidogermanates [Mn(en)₃]₂Ge₂Se₆ (en = ethylenediamine) and [Fe(dien)₂]₂Ge₂Se₆ (dien= diethylenetriamine) were synthesized by the reaction of germanium dioxide, elemental selenium, and transition metal chlorides in respectively en and dien. Both compounds crystallize in the monoclinic space group P2₁/n with two formula units in the unit cell, and consist of discrete [Ge₂Se₆]⁴⁻ anions with transition metal complex cations as counter ions. The [Ge₂Se₆]⁴⁻ anion is formed by two GeSe₄ tetrahedra sharing a common edge to form a planar Ge₂Se₂ four-membered ring. The [Mn(en)₃]²⁺ and [Ni(dien)₂]²⁺ complex cations are in distorted octahedral geometry. In both selenidogermanates extensive N–H···Se hydrogen bonding contacts lead to 3-dimensional network structures. The band gaps of 2.36 and 2.25 eV were derived from optical absorption spectra. Thermogravimetric analysis shows that the first compound decomposes in two steps under the nitrogen stream, while the second exhibits a one-step decomposition process.     

The First Examples of Selenidogermanate Salts with Lanthanide Complex Counter Cations: Solvothermal Syntheses and Characterizations of [{Ln(en)3}2(μ‐OH)2]Ge2Se6 (Ln = Eu,Ho) and [{Ho(dien)2}2(μ‐OH)2]Ge2Se6

The lanthanide selenidogermanates [{Eu(en)₃}₂(μ‐OH)₂]Ge₂Se₆ ( 1 ), [{Ho(en)₃}₂(μ‐OH)₂]Ge₂Se₆ ( 2 ), and [{Ho(dien)₂}₂(μ‐OH)₂]Ge₂Se₆ ( 3 ) (en = ethylenediamine, dien = diethylenetriamine) were solvothermally prepared by the reactions of Eu₂O₃ (or Ho₂O₃), germanium, and selenium in en and dien solvents respectively. Compounds 1 – 3 are composed of selenidogermanate [Ge₂Se₆]^4– anion and dinuclear lanthanide complex cation [{Ln(en)₃}₂(μ‐OH)₂]⁴⁺ (Ln = Eu, Ho) or [{Ho(dien)₂}₂(μ‐OH)₂]⁴⁺. The [Ge₂Se₆]^4– anion is composed of two GeSe₄ tetrahedra sharing a common edge. The dinuclear lanthanide complex cations are built up from two [Ln(en)₃]³⁺ or [Ho(dien)₂]³⁺ ions joined by two μ‐OH bridges. All lanthanide(III) ions are in eight‐coordinate environments forming distorted bicapped trigonal prisms. In 1 – 3 , three‐dimensional supramolecular networks of the anions and cations are formed by N–H ··· Se and N–H ··· O hydrogen bonds. To the best of our knowledge, 1 – 3 are the first examples of selenidogermanate salts with lanthanide complex counter cations.     

Extraction of Ternary Alloys: Synthesis and Crystal Structure of [K([2.2.2]crypt)]Cs7[Sn9]2(en)3

The compound [K([2.2.2]crypt)]Cs₇[Sn₉]₂(en)₃ ( 1 ) was synthesized from an alloy of formal composition KCs₂Sn₉ by dissolving in ethylenediamine (en) followed by the addition of [2.2.2]crypt and toluene. 1 crystallizes in the orthorhombic space group Pcca with a = 45.38(2), b = 9.092(4), c = 18.459(8) Å, and Z = 4. The structure consists of Cs₇[Sn₉]₂ layers which contain [Sn₉]^4– anions and Cs⁺ cations. The layers are separated by [K([2.2.2]crypt)]⁺ units. In the intermetallic slab (Cs₇[Sn₉]₂)^– compares the arrangement of pairs of symmetry‐related [Sn₉]^4– anions with the dimer ([Ge₉]–[Ge₉])^6– in [K([2.2.2]crypt)]₂Cs₄([Ge₉]–[Ge₉]), in which the clusters are linked by a cluster‐exo bond. The shortest distance between atoms of such two clusters in 1 is 4.762 Å, e. g. there are no exo Sn‐Sn bonds. The [Sn₉]^4– anion has almost perfect C_4v‐symmetry.     

Synthesis,Structural Characterization,and Physical Properties of Cs2Ga2S5, and Redetermination of the Crystal Structure of Cs2S6

The reaction of CsN₃ with GaS and S at elevated temperatures results in Cs₂Ga₂S₅. Its crystal structure was determined from single‐crystal X‐ray diffraction data. The colorless solid crystallizes in space group C2/c (no. 15) with V=1073.3(4) ų and Z=4. Cs₂Ga₂S₅ is the first compound that features one‐dimensional chains ${{{\hfill 1\atop \hfill \infty }}}$ [Ga₂S₃(S₂)^2?] of edge‐ and corner‐sharing GaS₄ tetrahedra. The vibrational band of the S₂^2? units at 493 cm^?1 was revealed by Raman spectroscopy. Cs₂Ga₂S₅ has a wide bandgap of about 3.26 eV. The thermal decomposition of CsN₃ yields elemental Cs, which reacts with sulfur to provide Cs₂S₆ as an intermediate product. The crystal structure of Cs₂S₆ was redetermined from selected single crystals. The red compound crystallizes in space group ${P\bar 1}$ with V=488.99(8) ų and Z=2. Cs₂S₆ consists of S₆^2? polysulfide chains and two Cs positions with coordination numbers of 10 and 11, respectively. Results of DFT calculations on Cs₂Ga₂S₅ are in good agreement with the experimental crystal structure and Raman data. The analysis of the chemical bonding behavior revealed completely ionic bonds for Cs, whereas Ga?S and S?S form polarized and fully covalent bonds, respectively. HOMO and LUMO are centered at the S₂ units.     

Synthese und Kristallstruktur von Cs3Y7Se12

Synthesis and Crystal Structure of Cs₃Y₇Se₁₂ The oxidation of yttrium metal with selenium in the presence of CsCl (7 d, 700°C, evacuated silicia tubes) results in the formation of pale yellow, lath-shaped single crystals of Cs₃Y₇Se₁₂. The crystal structure (orthorhombic, Pnnm, Z = 2, a = 1272.8(3), b = 2627.7(5), c = 413.32(8) pm) consists of edge- and vertex-connected [YSe₆] octahedra forming a rocksalt-related network [Y₇Se₁₂]^3?. One-dimensional infinite channels along [001], apt to take up extra cations, provide coordination numbers of 6 and 7 + 1, respectively, for two crystallographically different Cs⁺.     

[Cs6Cl][Fe24Se26]: A Host–Guest Compound with Unique Fe–Se Topology

The novel host–guest compound [Cs₆Cl][Fe₂₄Se₂₆] (I4/mmm; a=11.0991(9), c=22.143(2) Å) was obtained by reacting Cs₂Se, CsCl, Fe, and Se in closed ampoules. This is the first member of a family of compounds with unique Fe–Se topology, which consists of edge‐sharing, extended fused cubane [Fe₈Se₆Se_8/3] blocks that host a guest complex ion, [Cs₆Cl]⁵⁺. Thus Fe is tetrahedrally coordinated and divalent with strong exchange couplings, which results in an ordered antiferromagnetic state below T_N=221 K. At low temperatures, a distribution of hyperfine fields in the Mössbauer spectra suggests a structural distortion or a complex spin structure. With its strong Fe–Se covalency, the compound is close to electronic itinerancy and is, therefore, prone to exhibit tunable properties.     

Supercubooctahedron (Cs6Cl)2Cs5[Ga15Ge9Se48] Exhibiting Both Cation and Anion Exchange

A novel type of supertetrahedral connectivity is exhibited by the 72‐atom discrete supercubooctahedron in (Cs₆Cl)₂Cs₅[Ga₁₅Ge₉Se₄₈] ( 1 ), which undergoes both cation and anion exchange, as revealed by unambiguous single‐crystal X‐ray diffraction data. Electronic‐structure studies helped to understand the Ge/Ga distribution.     

Synthese und Kristallstruktur des Fluorid‐ino‐Oxosilicats Cs2YFSi4O10

Synthesis and Crystal Structure of the Fluoride ino‐Oxosilicate Cs₂YFSi₄O₁₀ The novel fluoride oxosilicate Cs₂YFSi₄O₁₀ could be synthesized by the reaction of Y₂O₃, YF₃ and SiO₂ in the stoichiometric ratio 2 : 5 : 3 with an excess of CsF as fluxing agent in gastight sealed platinum ampoules within seventeen days at 700 °C. Single crystals of Cs₂YFSi₄O₁₀ appear as colourless, transparent and water‐resistant needles. The characteristic building unit of Cs₂YFSi₄O₁₀ (orthorhombic, Pnma (no. 62), a = 2239.75(9), b = 884.52(4), c = 1198.61(5) pm; Z = 8) comprises infinite tubular chains of vertex‐condensed [SiO₄]^4? tetrahedra along [010] consisting of eight‐membered half‐open cube shaped silicate cages. The four crystallographically different Si⁴⁺ cations all reside in general sites 8d with Si–O distances from 157 to 165 pm. Because of the rigid structure of this oxosilicate chain the bridging Si–O–Si angles vary extremely between 128 and 167°. The crystallographically unique Y³⁺ cation (in general site 8d as well) is surrounded by four O^2? and two F^? anions (d(Y–O) = 221–225 pm, d(Y–F) = 222 pm). These slightly distorted trans‐[YO₄F₂]^7? octahedra are linked via both apical F^? anions by vertex‐sharing to infinite chains along [010] (?(Y–F–Y) = 169°, ?(F–Y–F) = 177°). Each of these chains connects via terminal O^2? anions to three neighbouring oxosilicate chains to build up a corner‐shared, three‐dimensional framework. The resulting hexagonal and octagonal channels along [010] are occupied by the four crystallographically different Cs⁺ cations being ten‐, twelve‐, thirteen‐ and fourteenfold coordinated by O^2? and F^? anions (viz.[(Cs1)O₁₀]^19?, [(Cs2)O₁₀F₂]^21?, [(Cs3)O₁₂F]^24?, and [(Cs4)O₁₂F₂]^25? with d(Cs–O) = 309–390 pm and d(Cs–F) = 360–371 pm, respectively).     

Neue Cyclosilicate der Alkalimetalle: Cs5AgSi3O9 und Cs6Na6Si6O18

New Alkali Cyclosilicates: Cs₅AgSi₃O₉ and Cs₆Na₆Si₆O₁₈ The new cyclosilicates were obtained from reactions of the binary oxides at 450–500 °C under inert gas atmosphere. Cs₅AgSi₃O₉ crystallizes in the space group P2₁/m with the lattice constants a = 968,2(2) pm, b = 652,7(1) pm, c = 1162,6(3) pm, β = 93,84(2)° and Cs₆Na₆Si₆O₁₈ in R‐3m with a = 1208,0(1) pm, c = 1458,9(2) pm (IPDS data sets). The characteristic features are isolated rings, [Si₃O₉]^6– and [Si₆O₁₈]^12–, respectively. In Cs₅AgSi₃O₉ these are connected via Ag⁺ to chains. Layers of [NaO₄]‐tetrahedra separate the hexameric rings in Cs₆Na₆Si₆O₁₈. Coordination numbers of caesium are observed between C.N. 3 and C.N. 9 in these alkali rich cyclosilicates. MAPLE calculations of both cyclosilicates as well as the absorption and IR spectrum of Cs₅AgSi₃O₉ are presented. Preparative and thermoanalytical techniques have been used to investigate the reactivity of Cs₅AgSi₃O₉ in the presence of cobalt and nickel metal.     

The New Cesium Praseodymium Thiophosphate Cs3Pr5[PS4]6

Transparent platelet‐shaped green single crystals of the title compound were obtained by the reaction of cesium bromide, praseodymium, sulfur, and red phosphorus in the molar ratio 1:2:8:2 with an excess of CsBr as flux in evacuated silica ampoules at 950 °C for fourteen days. Cs₃Pr₅[PS₄]₆ crystallizes monoclinically in the space group C2/c (a = 1627.78(7), b = 1315.09(6), c = 2110.45(9) pm, β = 103.276(5)°; Z = 4). Its crystal structure is different from all the other alkali‐metal containing ortho‐thiophosphates of the lanthanides, since it is not possible to formulate a layer containing the praseodymium centered sulfur polyhedra ([PrS₈]^13—, d(Pr—S) = 286 — 307 pm) and the isolated [PS₄]^3— tetrahedra (d(P—S) = 202 — 207 pm, ?(S—P—S) = 104 — 106°). All these tetrahedra are edge‐sharing with the metal polyhedra to build up a framework instead. The coordination sphere of the half occupied (Cs2)⁺ cations (CN = 10 + 2) can be described as two six‐membered sulfur rings in chair conformation containing a “cesium‐pair” in the middle. In contrast the (Cs1)⁺ cations are surrounded in the not unusual configuration of tetracapped trigonal prisms (CN = 10, better 10 + 2 as well).     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. VII. Anwendung der Theorie des freien Volumens auf Gläser und Schmelzen im System Germanium-Selen

Application of the Free Volume Theory to Glasses and Melts in the System Germanium–Selenium The temperature dependence on the molar volume of glasses and melts was measured for the compositions: Ge₅Se₇, Ge₂Se₃, Ge₃Se₇, GeSe₃, GeSe₅. Values of the free volume were calculated. Correlating this values according to free volume theory with data from the literature concerning the viscosity of the melts allows the estimation of the minimum required volume of the voids. Se is found as the unit of viscous flow for GeSe₂?Se-melts. The mechanism is discussed.     

Drei Alkalimetall‐Erbium‐Thiophosphate: Von der Schichtstruktur bei KEr[P2S7] zur dreidimensionalen Vernetzung in NaEr[P2S6] und Cs3Er5[PS4]6

Three Alkali‐Metal Erbium Thiophosphates: From the Layered Structure of KEr[P₂S₇] to the Three‐Dimensional Cross‐Linkage in NaEr[P₂S₆] and Cs₃Er₅[PS₄]₆ The three alkali‐metal erbium thiophosphates NaEr[P₂S₆], KEr[P₂S₇], and Cs₃Er₅[PS₄] show a small selection of the broad variety of thiophosphate units: from ortho‐thiophosphate [PS₄]^3? and pyro‐thiophosphate [S₃P–S–PS₃]^4? with phosphorus in the oxidation state +V to the [S₃P–PS₃]^3? anion with a phosphorus‐phosphorus bond (d(P–P) = 221 pm) and tetravalent phosphorus. In spite of all differences, a whole string of structural communities can be shown, in particular for coordination and three‐dimensional linkage as well as for the phosphorus‐sulfur distances (d(P–S) = 200 – 213 pm). So all three compounds exhibit eightfold coordinated Er³⁺ cations and comparably high‐coordinated alkali‐metal cations (CN(Na⁺) = 8, CN(K⁺) = 9+1, and CN(Cs⁺) ≈ 10). NaEr[P₂S₆] crystallizes triclinically ( ; a = 685.72(5), b = 707.86(5), c = 910.98(7) pm, α = 87.423(4), β = 87.635(4), γ = 88.157(4)°; Z = 2) in the shape of rods, as well as monoclinic KEr[P₂S₇] (P2₁/c; a = 950.48(7), b = 1223.06(9), c = 894.21(6) pm, β = 90.132(4)°; Z = 4). The crystal structure of Cs₃Er₅[PS₄] can also be described monoclinically (C2/c; a = 1597.74(11), b = 1295.03(9), c = 2065.26(15) pm, β = 103.278(4)°; Z = 4), but it emerges as irregular bricks. All crystals show the common pale pink colour typical for transparent erbium(III) compounds.     

Quaternäre Caesium‐Kupfer(I)‐Lanthanoid(III)‐Selenide vom Typ CsCu3M2Se5 (M = Sm,Gd — Lu)

Quaternary Cesium Copper(I) Lanthanoid(III) Selenides of the Type CsCu₃M₂Se₅ (M = Sm, Gd — Lu) By oxidation of mixtures of copper and lanthanoid metal with elemental selenium in molar ratios of 1 : 1 : 2 and in addition of CsCl quaternary cesium copper(I) lanthanoid(III) selenides with the formula CsCu₃M₂Se₅ (M = Sm, Gd — Lu) were obtained at 750 °C within a week from torch‐sealed evacuated silica tubes. An excess of CsCl as flux helps to crystallize golden yellow or red, needle‐shaped, water‐resistant single crystals. The crystal structure of CsCu₃M₂Se₅ (M = Sm, Gd — Lu) (orthorhombic, Cmcm, Z = 4; e. g. CsCu₃Sm₂Se₅: a = 417.84(3), b = 1470.91(8), c = 1764.78(9) pm and CsCu₃Lu₂Se₅: a = 407.63(3), b = 1464.86(8), c = 1707.21(9) pm, respectively) contains [MSe₆]^9— octahedra which share edges to form double chains running along [100]. Those are further connected by vertices to generate a two‐dimensional layer parallel to (010). By edge‐ and vertex‐linking of [CuSe₄]^7— tetrahedra two crystallographically different Cu⁺ cations build up two‐dimensional puckered layers parallel to (010) as well. These sheet‐like structure interconnects the equation/tex2gif-stack-3.gif{[M₂Se₅]^4—} layers to create a three‐dimensional network according to equation/tex2gif-stack-4.gif{[Cu₃M₂Se₅]^—}. Thus empty channels along [100] form, apt to take up the Cs⁺ cations. These are surrounded by eight plus one Se^2— anions in the shape of (2+1)‐fold capped trigonal prisms with Cs—Se distances between 348 and 368 pm (8×) and 437 (for M = Sm) or 440 pm (for M = Lu), respectively, for the ninth ligand.     

Cs10Tl6SiO4, Cs10Tl6GeO4, and Cs10Tl6SnO3 – First Oxotetrelate Thallides,Double Salts Containing “Hypoelectronic” [Tl6]6– Clusters

Cs₁₀Tl₆TtO₄ (Tt = Si, Ge) and Cs₁₀Tl₆SnO₃ were synthesized by the reaction of appropriate starting materials at 623–673 K, followed by fast cooling or quenching to room temperature, in arc‐welded tantalum ampoules. According to single‐crystal X‐ray analyses, the compounds crystallize in new structure types (Cs₁₀Tl₆TtO₄ (Tt = Si, Ge), P2₁/c and Cs₁₀Tl₆SnO₃, Pnma), consisting of [Tl₆]^6– clusters, which can be characterized as distorted octahedra compressed along one of the fourfold axes of an originally unperturbed octahedron, and [SiO₄]^4–, [GeO₄]^4– or [SnO₃]^4– anions. The oxotetrelate thallides can be regarded as “double salts”, which consist of Cs₆Tl₆ on one side and respective oxosilicates, ‐germanates and ‐stannates on the other, showing almost not any direct interaction between the two anionic moieties, as might be expressed e.g. by the formula [Cs₆Tl₆][Cs₄SiO₄]. In contrast to the silicon and germanium compounds, where the oxidation state of the tetrel atom is unambiguously 4+, for the threefold coordinated tin atom in Cs₁₀Tl₆SnO₃ an oxidation state of 2+ has to be assumed. Thus, the latter reveal further evidence that the so called “hypoelectronic” [Tl₆]^6– cluster does not require additional electrons and is intrinsically stable. The distortion of [Tl₆]^6– can be understood in terms of the Jahn–Teller theorem. According to magnetic measurements all title compounds are diamagnetic.     

Cs3Se22, a Selenium‐rich Caesium Polyselenide containing Se8 Crowns and $^{3}_{\infty}\rm [Se_{6}^{3-}]$ Anions with Radical Character

Cs₃Se₂₂ can be prepared together with the known compounds Cs₂Sn₂Se₆ and Cs₄Sn₂Se₆ by reacting Cs₂CO₃ and Sn in a CH₃OH/en solution at 120 °C. The presence of CuCl and the macrocyclic ligand 1,10‐dithia‐18‐crown‐6 are essential for product formation. The caesium polyselenide consists of anionic nets that are separated by two layers of discrete Se₈ rings. Within the polymeric anions pairs of Se₃^·− radical anions and Se₃²⁻ anions are linked through secondary interactions.     

Molten Salt Synthesis, Crystal Structure and Optical Properties of a Novel Quaternary Metal Selenide, K2AgIn3Se6

K2AgIn3Se6 was synthesized by a molten-salt (alkali-metal polyselenide flux) reaction at 500 ℃. The orange red granular crystal crystallizes in monoclinic space group C2/c with cell parameters, a=1.16411(7) nm, b=1.16348(8) nm, c=2.14179(12) nm, V=2.8740(9) nm^3, and Z=8. The crystal has a new two-dimensional structure containing ^2∞[AgIn3Se6]^2- anionic layers separated by K^- cations and the ^2∞[AgIn3Se6]^2- layer is constructed with corner-shared [AgSe4] and [InSe4] tetrahedra. The optical band gap of K2AgIn3Se6 was determined to be ca. 2.9 eV by UV/vis/NIR diffuse reflectance spectra.     

Synthesis and Structure of the Novel Pentaselenidohexaarsenate(I,II) Cluster Anion [As6Se5]2−

Methanolothermal reaction of [MnCl₃(9‐ane‐N₃)] with As₂Se₃ at 150 °C in the presence of Cs₂CO₃ affords violet‐coloured [Mn(9‐ane‐N₃)₂]As₆Se₅ ( 1 ). Its novel tricyclic selenidoarsenate(I,II) anion [As₆Se₅]^2? contains two five‐membered [As₃As(Se)Se] rings that are symmetry‐related by a crystallographic C₂ axis passing through the common As^I‐As^I bond between their respective first two ring members. The adjacent As^I atoms in the individual rings are bridged by the Se atom of the third [As₄Se] ring.     

Potassium sodium tin selenide,K3NaSn3Se8

The title compound, tripotassium sodium tritin octaselenide, K₃NaSn₃Se₈, has a molecular (zero‐dimensional) structure containing trimeric [Sn₃Se₈]^4? units which consist of three edge‐sharing SnSe₄ tetrahedra. The [Sn₃Se₈]^4? anions and the tetrahedrally coordinated Na⁺ cations are arranged in an alternating fashion along the c axis to form SiS₂‐like chains, which are then separated by eight‐coordinate K⁺ cations. The Sn—Se bond distances are normal, being in the range 2.477 (1)–2.612 (1) Å.     

Strukturelle Untersuchungen an Cs2[B12H12]

Structural Investigations on Cs₂[B₁₂H₁₂] The crystal structure of Cs₂[B₁₂H₁₂] has been determined from X‐ray single‐crystal data collected at room temperature. Dicesium dodecahydro‐closo‐dodecaborate crystallizes as colourless, face‐rich crystals (cubic, Fm 3; a = 1128.12(7) pm; Z = 4). Its synthesis is based on the reaction of Na[BH₄] with BF₃(O(C₂H₅)₂) via the decomposition of Na[B₃H₈] in boiling diglyme, followed by subsequent separations, precipitations (with aqueous CsOH solution) and recrystallizations. The crystal structure is best described as anti‐CaF₂‐type arrangement with the Cs⁺ cations in all tetrahedral interstices of the cubic closest‐packed host lattice of the icosahedral [B₁₂H₁₂]^2–‐cluster dianions. The intramolecular bond lengths are in the range usually found in closo‐hydroborates: 178 pm for the B–B and 112 pm for the B–H distance. Twelve hydrogen atoms belonging to four [B₁₂H₁₂]^2– icosahedra provide an almost perfect cuboctahedral coordination sphere to the Cs⁺ cations, and their distance of 313 pm (12 ×) attests for the salt‐like character of Cs₂[B₁₂H₁₂] according to {(Cs⁺)₂([B₁₂H₁₂]^2–)}. The ¹¹B{¹H}‐NMR data in aqueous (D₂O) solution are δ = –12,70 ppm (¹J_B–H = 125 Hz), and δ = –15,7 ppm (linewidth: δν_1/2 = 295 Hz) for the solid state ¹¹B‐MAS‐NMR.