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.     

Oxonium Ions Substituting Cesium Ions in the Structure of the New High‐Pressure Borate HP‐Cs1−x(H3O)xB3O5 (x=0.5–0.7)

The new high‐pressure borate HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7) was synthesized under high‐pressure/high‐temperature conditions of 6 GPa/900 °C in a Walker‐type multianvil apparatus. The compound crystallizes in the monoclinic space group C2/c (Z=8) with the parameters a=1000.6(2), b=887.8(2), c=926.3(2) pm, β=103.1(1)°, V=0.8016(3) nm³, R1=0.0452, and wR2=0.0721 (all data). The boron–oxygen network is analogous to those of the compounds HP‐MB₃O₅, (M=K, Rb) and exhibits all three structural motifs of borates—BO₃ groups, corner‐sharing BO₄ tetrahedra, and edge‐sharing BO₄ tetrahedra—at the same time. Channels inside the boron–oxygen framework contain the cesium and oxonium ions, which are disordered on a specific site. Estimating the amount of hydrogen by solid‐state NMR spectroscopy and X‐ray diffraction led to the composition HP‐Cs_1?x(H₃O)_xB₃O₅ (x=0.5–0.7), which implies a nonzero phase width.     

Polysulfonylamine. CLXIII [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 12 [1] Das orthorhombische Doppelsalz Na2Cs2[(CH3SO2)2N]4·3H2O: Ein dreidimensionales Koordinationspolymer aus (Caesium‐Anion‐Wasser)‐Schichten und intercalierten Natriumionen

Polysulfonylamines. CLXIII. Crystal Structures of Metal Di(methanesulfonyl)amides. 12. The Orthorhombic Double Salt Na₂Cs₂[(CH₃SO₂)₂N]₄·3H₂O: A Three‐Dimensional Coordination Polymer Built up from Cesium‐Anion‐Water Layers and Intercalated Sodium Ions The packing arrangement of the three‐dimensional coordination polymer Na₂Cs₂[(MeSO₂)₂N]₄·3H₂O (orthorhombic, space group Pna2₁, Z′ = 1) is in some respects similar to that of the previously reported sodium‐potassium double salt Na₂K₂[(MeSO₂)₂N]₄·4H₂O (tetragonal, P4₃2₁2, Z′ = 1/2). In the present structure, four multidentately coordinating independent anions, three independent aquo ligands and two types of cesium cation form monolayer substructures that are associated in pairs to form double layers via a Cs(1)—H₂O—Cs(2) motif, thus conferring upon each Cs⁺ an irregular O₈N₂ environment drawn from two N, O‐chelating anions, two O, O‐chelating anions and two water molecules. Half of the sodium ions occupy pseudo‐inversion centres situated between the double layers and have an octahedral O₆ coordination built up from four anions and two water molecules, whereas the remaining Na⁺ are intercalated within the double layers in a square‐pyramidal and pseudo‐C₂ symmetric O₅ environment provided by four anions and the water molecule of the Cs—H₂O—Cs motif. The net effect is that each of the four independent anions forms bonds to two Cs⁺ and two Na⁺, two independent water molecules are involved in Cs—H₂O—Na motifs, and the third water molecule acts as a μ₃‐bridging ligand for two Cs⁺ and one Na⁺. The crystal cohesion is reinforced by a three‐dimensional network of conventional O—H···O=S and weak C—H···O=S/N hydrogen bonds.     

Further Examples of the P‐O‐P Connection in Borophosphates: Synthesis and Characterization of Li2Cs2B2P4O15, LiK2BP2O8, and Li3M2BP4O14 (M=K,Rb)

A new series of anhydrous mixed alkali‐metal borophosphates—Li₂Cs₂B₂P₄O₁₅ ( 1 ), LiK₂BP₂O₈ ( 2 ), Li₃K₂BP₄O₁₄ ( 3 ), and Li₃Rb₂BP₄O₁₄ ( 4 )—have been successfully synthesized by using the conventional solid‐state reaction method. Compound 1 contains a novel fundamental building unit (FBU), [B₄P₈O₃₀], with B/P=1:2. Compound 2 contains an FBU of [B₂P₄O₁₆] with B/P=1:2. Compounds 3 and 4 are isotypic, and they have a [B(P₂O₇)₂] unit as their FBU. In all four compounds, their FBUs are connected through corner sharing to generate layered anionic partial structures, and then further linked with metallic polyhedra to form three‐dimensional (3D) frameworks. Most interestingly, three of the four compounds contain direct P‐O‐P connections in their structures, which is extremely rare among borophosphates. Thermal analyses, IR spectroscopy, and UV/Vis/near‐IR diffuse reflectance spectroscopy have also been performed on the four title compounds.     

The Zintl Phase Cs7NaSi8 – From NMR Signal Line Shape Analysis and Quantum Mechanical Calculations to Chemical Bonding

Powder samples as well as red and transparent single crystals of the Zintl phase Cs₇NaSi₈ were synthesized and characterized by means of X‐ray diffraction and differential thermal analysis. Cs₇NaSi₈ was found to be isotypic to the recently reported phase Rb₇NaSi₈. It crystallizes in the Rb₇NaGe₈ structure type forming trigonal pyramidal Si₄^4– anions. Two unique environments of the cations are observed, a linear arrangement [Na(Si₄)₂]^7– with short Na–Si distances of 3.0 Å and a Cs2 atom coordinated by six Si₄^4– anions with long Cs–Si distances of 4.2 Å. The bonding situation was investigated by a combined application of ²⁹Si, ²³Na, and ¹³³Cs solid‐state NMR spectroscopy and quantum mechanical calculations of the NMR coupling parameters. In addition the electronic density of states (DOS), the electron localizability indicator (ELI) and the atomic charges using the QTAIM approach were studied. Good agreement of the calculated and experimental values of the NMR coupling parameters was obtained. An anisotropic bonding situation of the silicon atoms is indicated by the chemical shift anisotropy being similar to Rb₇NaSi₈. Confirmation is given by the observation of one lone‐pair‐like feature for each silicon atom and two types of two‐center Si–Si bonds using the ELI. Calculation and NMR spectroscopic determination of the ²³Na and ¹³³Cs electric field gradients prove anisotropies of the charge distribution around the cations. Due to the similar values for the Na atoms in M₇NaSi₈ (M = Rb, Cs) equal bonding situations can be concluded. The much larger anisotropy of the charge distribution of the Cs atoms can be addressed as the main difference to Rb₇NaSi₈.     

Suboxides with Complex Anions: The Suboxoindate Cs9InO4

Salty metal : In the suboxometallate Cs₉InO₄, metallic cesium columns (see picture; blue) lie next to ionic oxoindate(III) columns. The chemistry of the suboxides is thus expanded to structures containing complex anions.

     

Enhancement of the positive secondary ion yield during low‐energy,dual‐beam depth profiling of polytetrafluoroethylene with 1‐keV Cs+

This work documents the behaviour of the positive secondary ion yield of bulk polytetrafluoroethylene (PTFE) under dual‐beam depth profiling conditions employing 1 keV Ar⁺, Cs⁺ and SF₅⁺. A unique chemical interaction is observed in the form of a dramatic enhancement of the positive secondary ion yield when PTFE is dual‐beam profiled with 1 keV Cs⁺. The distinct absence of such an enhancement is noted for comparison on two non‐fluorinated polymers, polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS). The bulk PTFE was probed using 15‐keV, ⁶⁹Ga⁺ primary ions in dual beam mode under static conditions; 1‐keV Ar⁺ (a non‐reactive, light, noble element), Cs⁺ (a heavier metallic ion known to form clusters) and SF₅⁺ (a polyatomic species) served as the sputter ion species. The total accumulated primary ion dose was of the order of 10¹⁵ ions/cm², which is well beyond the static limit. The enhancement of the positive secondary yield obtained when profiling with 1‐keV Cs⁺ far exceeds that obtained when SF₅⁺ is employed. An explanation of this apparent reactive ion effect in PTFE is offered in terms of polarisation of C? F bonds by Cs⁺ in the vicinity of the implantation site thereby predisposing them to facile scission. The formation of peculiar, periodic Cs_xF_y⁺ (where y = x ? 1) and Cs_xC_yF_z⁺ clusters that can extend to masses approaching 2000 amu are also observed. Such species may serve as useful fingerprints for fluorocarbons that can be initiated via pre‐dosing a sample with low‐energy Cs⁺ prior to static 15‐keV Ga⁺ analysis. Copyright © 2005 John Wiley & Sons, Ltd.     

Methanolothermal Synthesis and Structures of the Quaternary Group 14 – Group 15 Cesium Selenidometalates Cs3AsGeSe5 and Cs4Ge2Se6

Cs₃AsGeSe₅ and Cs₄Ge₂Se₆ can be prepared by methanolothermal reaction of elemental As, Ge and Se with Cs₂CO₃ at 190 °C. The former quaternary phase contains zweier [{AsGeSe₅}^3?] chains consisting of corner‐bridged GeSe₄ tetrahedra and AsSe₃ pyramids and represents the first Ge^IV‐As^III chalcogenidometalate. Cs₄Ge₂Se₆ exhibits discrete [Ge₂Se₆]^4? anions formed by two edge‐sharing GeSe₄ tetrahedra.     

Cs2BeCl4 und Cs2 YbCl4: Endglieder der homologen Reihe Cs2MCl4

Cs₂BeCl₄ and Cs₂YbCl₄: End Members of the Homologous Series Cs₂MCl₄ Cs₂BeCl₄ belongs to the β-K₂SO₄ type structure (orthorhombic, Pnma, Z = 4, a = 964.2(4), b = 717.8(3), c = 1246.8(5) pm) and Cs₂YbCl₄ to the K₂NiF₄ type (tetragonal, I4/mmm, Z = 2, a = 541.8(2), c = 1727.6(10) pm). They are with the exception of Cs₂TmCl₄ the end members of minimum and maximum molar volume of the homologous series Cs₂MCl₄. The application of the “theorem of optimal (preferred) volumes” suggests that the other members of the series also can only belong to one of these two structure types (β-K₂SO₄ and K₂NiF₄ type, respectively).     

Preparation and Crystal Structure of the Clathrate‐I Cs8–xGe44+y□2–y

The clathrate‐I phase Cs_8–xGe_44+y□_2–y (space group Pm$\bar{3}$ n) was prepared by high‐pressure high‐temperature reactions of Cs₄Ge₄ and α‐Ge. Different reaction conditions were found to have a strong influence on the lattice parameter of the clathrate‐I phase ranging from 10.8070(2) Å to 10.8493(3) Å. A single crystal with composition Cs₈Ge_44.40(2)□_1.60(2) was obtained from a sample with a = 10.8238(2) Å (niobium ampoule, p = 3.4 GPa, T_max = 1400 °C). Structure analysis based on X‐ray single crystal data shows unambiguously an excess of germanium atoms with respect to the electron balanced composition Cs₈Ge₄₄□₂ on basis of the Zintl concept.     

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.     

Polysulfonylamine. CLXV [1] Kristallstrukturen von Metall‐di(methansulfonyl)amiden. 14 [1] Cs3Ag[(MeSO2)2N]4 und CsAg[(MeSO2)2N]2: Ein dreidimensionales und ein schichtförmiges Koordinationspolymer mit Bis(dimesylamido‐N)argentat‐Baugruppen

Polysulfonylamines. CLXV. Crystal Structures of Metal Di(methanesulfonyl)amides. 14. Cs₃Ag[(MeSO₂)₂N]₄ and CsAg[(MeSO₂)₂N]₂: A Three‐Dimensional and a Layered Coordination Polymer Containing Bis(dimesylamido‐N)argentate Building Blocks Serendipitous formation pathways and low‐temperature X‐ray structures are reported for the coordination compounds Cs₃A₂[AgA₂] ( 1 ) and Cs[AgA₂] ( 2 ), where A^— represents the pentadentate dimesylamide ligand (MeSO₂)₂N^—. Both phases (monoclinic, space group C2/c, Z′ = 1/2) contain inversion‐symmetric bis(dimesylamido‐N)argentate units displaying exactly linear N—Ag—N cores and short, predominantly covalent Ag—N bonds [ 1 : 213.5(2), 2 : 213.35(12) pm]; in each case, the coordination number of the silver ion is extended to 2 + 6 by four internal and two external Ag···O secondary interactions. The three‐dimensional coordination polymer 1 is built up from alternating layer substructures [{Cs(1)}{A}_4/2]^— with Cs(1) lying on twofold rotation axes and [{Cs(2)}₂{AgA₂}_4/4]⁺ with Cs(2) occupying general positions. Within the substructural layers, both types of cesium cation have approximately planar O₄ environments, whereas the final coordination spheres including interlayer bonds are extended to O₆ for Cs(1) and to O₈N for Cs(2). Compound 2 , in contrast, forms a genuine layer structure. The layers are constructed from Cs⁺ chains located on twofold rotation axes, alternating with [AgA₂]^— stacks reinforced by Ag···O secondary interactions and weak C—H···O hydrogen bonds; Cs⁺ is embedded in an O₈ environment. Both structures are pervaded by a three‐dimensional C—H···O network.     

Colloidal Synthesis and Charge‐Carrier Dynamics of Cs2AgSb1−yBiyX6 (X: Br,Cl; 0 ≤y ≤1) Double Perovskite Nanocrystals

A series of lead‐free double perovskite nanocrystals (NCs) Cs₂AgSb_1?yBi_yX₆ (X: Br, Cl; 0≤y≤1) is synthesized. In particular, the Cs₂AgSbBr₆ NCs is a new double perovskite material that has not been reported for the bulk form. Mixed Ag–Sb/Bi NCs exhibit enhanced stability in colloidal solution compared to Ag–Bi or Ag–Sb NCs. Femtosecond transient absorption studies indicate the presence of two prominent fast trapping processes in the charge‐carrier relaxation. The two fast trapping processes are dominated by intrinsic self‐trapping (ca. 1–2 ps) arising from giant exciton–phonon coupling and surface‐defect trapping (ca. 50–100 ps). Slow hot‐carrier relaxation is observed at high pump fluence, and the possible mechanisms for the slow hot‐carrier relaxation are also discussed.     

Photoabsorption spectra of Cs n O and Cs n clusters

Photoabsorption spectra of several Cs _N+2O and Cs _N clusters were obtained by means of laser-induced beam-depletion techniques. The strong absorption of clusters withN≥3 in the near infrared indicates that collective motion might play an important role. Dipole transitions between molecular orbitals, enhanced by plasmon oscillations, generate remarkably distinct spectra for(a) closed-shell clusters atN=8 and(b) geometrically symmetric clusters like Cs₆O and Cs₁₄O.     

Synthesis,Luminescence and Nonlinear Optical Properties of Homoleptic Tetracyanamidogermanates ARE[Ge(CN2)4] (A = K,Cs, and RE = La,Ce, Pr,Nd, Sm,Eu, Gd)

Two new series of tetracyanamidogermanates were prepared by solid‐state reaction of appropriate amounts of REF₃ (RE = rare earth), A₂[GeF₆] (A = alkaline), and Li₂(CN₂) in evacuated silica tubes. Powder X‐ray diffraction patterns of crystalline samples of KRE[Ge(CN₂)₄] and CsRE[Ge(CN₂)₄] were indexed isotypically to KRE[Si(CN₂)₄] and RbRE[Ge(CN₂)₄], respectively. Luminescence properties of Ce³⁺, Eu³⁺, and Tb³⁺ doped compounds and non‐linear optical properties (NLO) of KRE[Ge(CN₂)₄] are reported.     

Struktur und magnetische Eigenschaften von Cs2Mn3S4 und Cs2Co3S4

Structure and Magnetic Properties of Cs₂Mn₃S₄ and Cs₂Co₃S₄ The atomic arrangements of the isotypic compounds Cs₂Mn₃S₄ and Cs₂Co₃S₄ were determined by X-ray investigations on single crystals (space group Ibam, Z = 4). To interprete the magnetic properties of Cs₂Mn₃S₄ mixed crystals of the series Cs₂(Mn_xZn_1-x)₃S₄ have been examined. Additionally neutron diffraction experiments were carried out and yielded the spin structures of Cs₂Mn₃S₄ and Cs₂Co₃S₄ (Shubnikov space group Ibam'). The deviations of the magnetic moments from those expected for high-spin d⁵ ions are explained by means of crystal field calculations.     

A monoclinic form of anhydrous Cs2PdCl4

A previously unreported monoclinic form of Cs₂PdCl₄ is described. It is found to transform into the reported orthorhombic form on exposure to atmospheric moisture. Infrared spectroscopy and TGA analysis of the previously reported orthorhombic form of Cs₂PdCl₄ reveals that it is a hydrate with a formula of approximately Cs₂PdCl₄:4H₂O. Water is not present in the monoclinic material. The compound is non-magnetic, which is attributed to a low spin configuration for 4 d⁸ Pd²⁺ in square planar coordination with Cl. The band gaps of the two forms are found to be 2.13 and 2.21 eV, consistent with their colors. A DFT-calculated electronic structure for the monoclinic form is presented.     

Die Oxoantimonate(III) Rb2Sb8O13 und Cs8Sb22O37: Neue Schicht‐ und Gerüststrukturen mit ‘Lone‐Pair’ ‐Kationen

The Oxoantimonates(III) Rb₂Sb₈O₁₃ and Cs₈Sb₂₂O₃₇: New Framework and Layer Structures with ‘Lone‐Pair’ Cations The oxoantimonates(III) Rb₂Sb₈O₁₃ and Cs₈Sb₂₂O₃₇ were synthezised from Sb₂O₃, the elemental alkali metals (A) and the hyperoxides (AO₂) at 500 °C. The crystal structures of Rb₂Sb₈O₁₃ (monoclinic, P2₁/m, a=743.7(12)pm, b=1724(3)pm, c=1380(2)pm, β=90.44(4) °, Z=4) and Cs₈Sb₂₂O₃₇ (monoclinic, Cc, a=1299.93(11)pm, b=719.87(6)pm, c=3089.9(3)pm, β=96.00(2) °, Z=2) exhibit complex layer (Rb) and framework oxoantimonate ions (Cs), with the Sb^III cation, due to its stereochemically active ‘lone‐pair’, in ψ‐tetrahedral (CN=3) to ψ‐trigonal‐bipyramidal (CN=4) coordination by O.     

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.