Cesium Platinide Hydride 4Cs2Pt⋅CsH: An Intermetallic Double Salt Featuring Metal Anions

With Cs₉Pt₄H a new representative of ionic compounds featuring metal anions can be added to this rare‐membered family. Cs₉Pt₄H exhibits a complex crystal structure containing Cs⁺ cations, Pt^2? and H^? anions. Being a red, transparent compound its band gap is in the visible range of the electromagnetic spectrum and the ionic type of bonding is confirmed by quantum chemical calculations. This cesium platinide hydride can formally be considered as a double salt of the “alloy” cesium–platinum, or better cesium platinide, Cs₂Pt, and the salt cesium hydride CsH according to Cs₉Pt₄H≡4 Cs₂Pt?CsH.     

Halogenomercury Salts of Sterically Crowded Triazenides – Convenient Starting Materials for Redox‐Transmetallation Reactions

Diaryl‐substituted triazenides Ar(Ar′)N₃HgX [Ar/Ar′ = Dmp/Mph, X = Cl ( 2a ), Br ( 3a ), I ( 4a ); Ar/Ar′ = Dmp/Tph, X = Cl ( 2b ), I ( 4b ) with Mph = 2‐MesC₆H₄, Mes = 2,4,6‐Me₃C₆H₂, Tph = 2′,4′,6′‐triisopropylbiphenyl‐2‐yl and Dmp = 2,6‐Mes₂C₆H₃] were synthesized by salt‐metathesis reactions in ethyl ether from the readily available starting materials Ar(Ar′)N₃Li and HgX₂. These compounds may be used for redox‐transmetallation reactions with rare‐earth or alkaline earth metals. Thus, reaction of 4b or 2b with magnesium or ytterbium in tetrahydrofuran afforded the triazenides Dmp(Tph)N₃MX(thf) ( 5b : M = Mg, X = I; 6b : M = Yb, X = Cl) in good yield. All new compounds were characterized by melting point, ¹H and ¹³C NMR spectroscopy and for selected species by IR spectroscopy or mass spectrometry. In addition, the solid‐state structures of triazenides 2a , 2b , 3a , 4b , 5b and 6b were investigated by single‐crystal X‐ray diffraction.     

Exploring the Anion–Cation Interaction in m‐Terphenyltetrafluorosilicates by Using Multinuclear NMR Spectroscopy,X‐ray Diffraction,and ICR‐FT‐MS

The synthesis of a series of m‐terphenyl‐substituted tetrafluorosilicates with different cations (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺) is described and the interactions between the anion and cation are investigated in the solid, solution, and gas states by using multinuclear NMR spectroscopy, X‐ray diffraction, and ion cyclotron resonance Fourier‐transform mass spectrometry (ICR‐FT‐MS). In solution, heteronuclear NMR spectroscopy parameters show only limited sensitivity to the nature of the cation, which furthermore can be affected by solvent effects. More pronounced effects are observed in the structural data obtained from X‐ray diffraction studies, which are in good agreement with experimental gas‐phase data from ESIMS. ESIMS also reveals the existence of dimeric species of the type [M(DmpSiF₄)₂]^? (Dmp=2,6‐dimesitylphenyl), the stability of which was determined by normalized collision energy experiments.     

Crystal structure,phase transitions and dielectric properties of the mixed compound [Cs0.92(NH4)0.08]2HgBr4

The crystal structure of [Cs_0.92 (NH₄)_0.08]₂HgBr₄ was determined by three-dimensional X-ray diffraction analysis. The space group is Pnma with a = 10.210(2), b = 7.928(1), c = 13.883(1)Å and Z = 4 at 293K. The structure was refined to R = 0.067. The distribution of atoms can be described as isolated HgBr₄²⁻tetrahedra , Cs⁺ and NH₄⁺ cations. The main feature of this structure is the coexistence of two types of bonds: Cs⁺  Br⁻ ionic bonds and NH…Br hydrogen bonds ensuring the cohesion of the crystal. Dicaesium-ammonium tetrabromomercurate exhibits three phase transitions at T₁ = 237K, T₂ = 244K and T₃ = 513K. These transitions were detected by differential scanning calorimetry and analysed by dielectric measurements using the impedance and modulus spectroscopy techniques. The phase change at high temperature is related with the orientational disorder of NH₄⁺ cations. Transport properties in this material appear to be due to a H⁺ ion hopping mechanism.     

Detection of a ferroelastic phase transition in Csx(NH4)1−xLiSO4 with the use of the DSC method

In this paper the technology of producing solid solutions of Cs_x(NH₄)_1?xLiSO₄ using the slow evaporation method is presented. Appropriate conditions were chosen to grow large samples. The ammonium ion content in the solid solutions was determined using the Kjeldahl method. It was found that the real ammonium ion concentration is twice lower than the one applied in the initial substances. At room temperature, the base crystal, lithium cesium sulfate (CsLiSO₄), is paraelastic, whereas lithium ammonium sulfate (NH₄LiSO₄) is ferroelectric. It is expected that as a result of substituting Cs⁺ ions with $ N{\text{H}}_{4}^{ + } $ N H 4 + ions, instead of the Cs⁺ ions, the modification of the ferroic properties of solid solutions of Cs_x(NH₄)_1?xLiSO₄ will take place. Tests conducted with the use of the differential scanning calorimetry method (DSC) allowed the detection of the ferroelastic phase transition which takes place in these compounds. A gradual increase of temperature transition was observed from 202 K for the pure CsLiSO₄ to 203.8 K for Cs_0.90(NH₄)_0.10LiSO₄ and 230.1 K for Cs_0.85(NH₄)_0.15LiSO₄ with the increase of $ N{\text{H}}_{4}^{ + } $ N H 4 + ions concentration. Using polarized light microscopy, a ferroelastic domain structure was detected in the examined solid solutions, which appeared below the structural phase transition temperature.     

Competitive binding exchange between alkali metal ions (K+, Rb+, and Cs+) and Na+ ions bound to the dimeric quadruplex [d(G4T4G4)]2: a 23Na and 1H NMR study

A comparative study of the competitive cation exchange between the alkali metal ions K⁺, Rb⁺, and Cs⁺ and the Na⁺ ions bound to the dimeric quadruplex [d(G₄T₄G₄)]₂ was performed in aqueous solution by a combined use of the ²³Na and ¹H NMR spectroscopy. The titration data confirm the different binding affinities of these ions for the G‐quadruplex and, in particular, major differences in the behavior of Cs⁺ as compared to the other ions were found. Accordingly, Cs⁺ competes with Na⁺ only for the binding sites at the quadruplex surface (primarily phosphate groups), while K⁺ and Rb⁺ are also able to replace sodium ions located inside the quadruplex. Furthermore, the ¹H NMR results relative to the CsCl titration evidence a close approach of Cs⁺ ions to the phosphate groups in the narrow groove of [d(G₄T₄G₄)]₂. Based on a three‐site exchange model, the ²³Na NMR relaxation data lead to an estimate of the relative binding affinity of Cs⁺ versus Na⁺ for the quadruplex surface of 0.5 at 298 K. Comparing this value to those reported in the literature for the surface of the G‐quadruplex formed by 5′‐guanosinemonophosphate and for the surface of double‐helical DNA suggests that topology factors may have an important influence on the cation affinity for the phosphate groups on DNA. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of Cs+ ions on the electrochemical nanogravimetric response of platinum electrode in acid media

Platinum electrodes have been investigated in sulfuric acid solutions in the presence and absence of Cs⁺ ions by electrochemical quartz crystal nanobalance (EQCN). An unusual potential dependence of the quartz crystal frequency response has been observed in the presence of Cs⁺ ions. The frequency decrease is more pronounced in the region of the underpotential deposition of hydrogen, and the frequency decrease in the double layer region diminishes as the concentration ratio of Cs⁺ and H⁺ ions increases. After immersion in Cs₂SO₄ solutions the frequency change was higher than that expected taking into account the density and viscosity. The effects observed can be explained by the specific adsorption of Cs⁺ ions on the Pt surface, which competes with the hydrogen adsorption. At more positive potentials than the potential of zero charge (pzc) a desorption of the Cs⁺ ions starts. In this potential region both Cs⁺ and HSO₄^? ions are adsorbed at the platinum surface. In the double layer region the mass change caused by the desorption of Cs⁺ ions and the starting adsorption of sulfate ions compensates each other.     

Interactions magnetiques intra- et interclusters dans les perovskites hexagonales Cs4Ni3CdF12(12R) et Cs5Ni4CdF15(10H)

The magnetic properties of Cs₄Ni₃CdF₁₂(12R) and Cs₅Ni₄CdF₁₅(10H) have been interpreted in terms of isolated entities in a large temperature range (T > 20 K). The model is based on a Heisenberg-Dirac-Van Vleck Hamiltonian. The intracluster magnetic interactions are ferromagnetic. At low temperature one has to take account of the intercluster interactions and of the zero-field splitting of Ni²⁺ to give a more satisfying interpretation of the magnetic behavior.     

Reduction‐Induced Highly Selective Uptake of Cesium Ions by an Ionic Crystal Based on Silicododecamolybdate

Cation adsorption and exchange has been an important topic in both basic and applied chemistry relevant to materials synthesis and chemical conversion, as well as purification and separation. Selective Cs⁺ uptake from aqueous solutions is especially important because Cs⁺ is expensive and is contained in radioactive wastes. However, the reported adsorbents incorporate Rb⁺ as well as Cs⁺, and an adsorbent with high selectivity toward Cs⁺ has not yet been reported. Highly selective uptake of Cs⁺ by an ionic crystal (etpyH)₂[Cr₃O(OOCH)₆(etpy)₃]₂[α‐SiMo₁₂O₄₀]?3 H₂O (etpy =4‐ethylpyridine) is described. The compound incorporated up to 3.8 mol(Cs⁺) mol(s)^?1 (where s=solid) by cation‐exchange with etpyH⁺ and reduction of silicododecamolybdate with ascorbic acid. The amount of Cs⁺ uptake was comparable to that of Prussian blue, which is widely recognized as a good Cs⁺ adsorbent. Moreover, other alkali‐metal and alkaline‐earth‐metal cations were almost completely excluded (<0.2 mol mol(s)^?1).     

Synthèse et structures cristallines de Cs3MI4NO3 (M = Zn,Co, Cd): Un exemple de substitution sélective

The compounds Cs₃MX₅ (M is a bivalent metal, and X an halogen) consist of Cs⁺, I⁻, and distorted (MI₄)²⁻ ions. The separate X⁻ ion suggests a possible substitution by another monovalent anion. The new compounds Cs₃MI₄NO₃ (M = Zn, Co, Cd) have been synthesized and characterized by X-ray diffraction. They are orthorhombic Pnma, a = 10.114(4), b = 11.601(5), c = 14.290(9) Å for Cs₃ZnI₄ NO₃; a = 10.078(8), b = 11.621(4), c = 14.262(6) Å for Cs₃CoI₄NO₃; a = 10.177(4), b = 11.784(5), c = 14.336(7) Å for Cs₃CdI₄NO₃; Z = 4. The crystal structures are described. The NO₃ groups surrounded by six Cs⁺ cations occupy the same sites as the separate I⁻ ion in the Cs₃MI₅ compounds.     

Investigation of cation environment and framework changes in silicotitanate exchange materials using solid-state Na, Si, and Cs MAS NMR

Crystalline silicotitanate (CST), HNa₃Ti₄Si₂O₁₄·4H₂O and the Nb-substituted CST (Nb-CST), HNa₂Ti₃NbSi₂O₁₄·4H₂O, are highly selective Cs⁺ sorbents, which makes them attractive materials for the selective removal of radioactive species from nuclear waste solutions. The structural basis for the improved Cs⁺ selectivity in the niobium analogs was investigated through a series of solid-state magic angle spinning (MAS) NMR experiments. Changes in the local environment of the Na⁺ and Cs⁺ cations in both CST and Nb-CST materials as a function of weight percent cesium exchange were investigated using ²³Na and ¹³³Cs MAS NMR. Framework changes induced by Cs⁺ loading and hydration state were investigated with ²⁹Si MAS NMR. Multiple Cs⁺ environments were observed in the CST and Nb-CST material. The relative population of these different Cs⁺ environments varies with the extent of Cs⁺ loading. Marked changes in the framework Si environment were noted with the initial incorporation of Cs⁺, however with increased Cs⁺ loading the impact to the Si environment becomes less pronounced. The Cs⁺ environment and Si framework structure were influenced by the Nb-substitution and were greatly affected by the amount of water present in the materials. The increased Cs⁺ selectivity of the Nb-CST materials arises from both the chemistry and geometry of the tunnels and pores.     

Calorimetric Investigation of the Complexation of Didodecylcalix[4]arene-crown-6 with Alkali Metal and Ammonium Cations in Acetonitrile

Abstract

The Cs⁺ selectivity of some calix-crown ligands makes them excellent candidates for use in separation systems such as liquid membranes. Separation performance can be understood and predicted from thermodynamic data for cation complexation. We have therefore determined the log K, ΔH and ΔS for the interaction of Na⁺, K⁺, Rb⁺, Cs⁺ and NH₄ ⁺ with didodecyl-calix[4]arene-crown-6 in acetonitrile at 25°C by titration calorimetry. The ligand is strongly selective for Cs⁺, and the selectivity trend results entirely from the enthalpy contribution, with entropy effects opposing the trend. These results are discussed in light of some corresponding data obtained by other researchers with similar ligands.     

Darstellung und Kristallstruktur der bekannten Zintl‐Phasen Cs3Sb7 und Cs4Sb2

Synthesis and Crystal Structure of the known Zintl Phases Cs₃Sb₇ and Cs₄Sb₂ Cs₃Sb₇ and Cs₄Sb₂ were synthesized from the elements and their crystal structures were determined on the basis of single crystal x‐ray data. Cs₃Sb₇ crystallizes in the monoclinic system with space group P2₁/c (a = 1605.7(1) pm, b = 1571.1(1) pm, c = 2793.9(2) pm, β = 96.300(2)°, Z = 16) and contains anions Sb₇^3–. In the structure of Cs₄Sb₂ (orthorhombic, space group Pnma, a = 1598.5(3) pm, b = 631.9(2) pm, c = 1099.5(2) pm, Z = 4) dumbbells Sb₂^4– are present.     

Syntheses and Properties of New Pendant‐armed Calix[4]arene Derivatives as Cesium Selective Ionophore

Two new pendant‐armed calix[4]arene derivatives 5 and 6 have been synthesized. The study of alkali metal picrates extraction indicates that both compounds show preference of cesium cation, compound 6 in 1,3‐alternate conformation has better extractibility for Cs⁺ than compound 5. The coordination behavior of compound 6 with cesium cation was studied by ¹H NMR spectroscopy. The Cs⁺ selective electrode based on compound 6 exhibits a linear, near Nernstian response characteristics, the slope is 56.4 mV/decade in me concentration range of 10^?4—10^?1 mol/L, the selectivity coefficient (logK^pot_Cs.Na) is ?3.39.     

Crystal chemistry peculiarities of Cs2Te4O12

The Raman and IR-absorption spectra of the Cs₂Te₄O₁₂ lattice are first recorded and interpreted. Extraordinary features observed in the structure and Raman spectra of Cs₂Te₄O₁₂ are analyzed by using ab initio and lattice-dynamical model calculations. This compound is specified as a caesium-tellurium tellurate Cs₂Te^IV(Te^VIO₄)₃ in which Te^IV atoms transfer their 5p electrons to [Te^VIO₄]₃⁶⁻ tellurate anions, thus fulfilling (jointly with Cs atoms) the role of cations. The Te^VI-O-Te^VI bridge vibration Raman intensity is found abnormally weak, which is reproduced by model treatment including the Cs⁺ ion polarizability properties in consideration.     

Synthesis of PAN/ferrocyanide composite incorporated with cetrimonium bromide and its employment as a bifunctional adsorbent for coremoval of Cs+ and HCrO4− from aqueous solutions

Polyacrylonitrile/ferrocyanide composite incorporated with cetrimonium bromide (PFICB) was synthesized and evaluated as a novel bifunctional adsorbent for coremoval of Cs⁺ and HCrO₄^?. Results of the reaction time effect showed that adsorption of Cs⁺ and HCrO₄^? onto PFICB were rapid processes. The effect of the solution pH in the range 2.5–10 revealed that PFICB had the ability to simultaneously remove Cs⁺ and HCrO₄^?. The maximum adsorption capacity of PFICB was found to be 41.79 mg/g for Cs⁺ and 19.39 mg/g for HCrO₄^?. These values were compared with those reported in literature using other adsorbents.

     

Über Cs2TlBr5 – ein Pentabromothallat (III) mit tetraedrischen TlBr4− - und oktaedrischen TlBr63− -Anionen

On Cs₂TlBr₅ — a Pentabromothallat (III) with Tetrahedral TlBr₄^? and Octahedral TlBr₆^3? Anions Cs₂TlBr₅ has been synthesized by crystallization from aqueous TlBr₃/CsBr solutions. The orthorhombic structure (a = 1330.2(11); b = 777.0(3); c = 2349.3(6) pm; Z = 8, space group Pnma-Nr. 62) contains isolated tetrahedral TlBr₄- and octahedral TlBr₆^3? anions which are packed together with the Cs⁺ cations in an anti-CaWO₄ arrangement. At 260°C Cs₂TlBr₅ decomposes irreversibly to Cs₃Tl₂Br₉ and CsBr.     

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.     

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.     

Cs2Cr4O13: a new structure type among alkali tetrachromates

Dicaesium tetrachromium(VI) tridecaoxide, Cs₂Cr₄O₁₃, contains finite [Cr₄O₁₃]²⁻ anions composed of four corner‐linked CrO₄ tetrahedra. These anions are linked by Cs⁺ cations whose Cs—O bond lengths range between 3.015 (2) and ∼3.7 Å. Although Cs₂Cr₄O₁₃ is not isotypic with its NH₄, K or Rb analogs, the [Cr₄O₁₃]²⁻ anions in all these compounds exhibit a similar zigzag‐like geometry.