A 8Tl11 (A = K,Rb, or Cs) phases with hypoelectronic Tl11 7− cluster anions: Syntheses,structure, bonding,and properties

The title compounds, which are synthesized from be elements, are shown to be isostructural with K₈In₁₁ (R3¯c Z=6) and to contain pentacapped trigonal prismatic clusters that have been compressed along the three-fold axes so as to bring the two types of capping atoms within bonding distances. These are arranged in double-ccp layers separated by double alkali--metal layers. Extended Hückel calculations show a substantial energy gap and the end of significant intracluster bonding for the hypoelectronic (by Wade's rules) 18-electron Tl₁₁ ^7?. Correspondingly, all three compounds are metallic (ρ₂₉₈ ≈ 400 μΩ · cm) and Pauli-paramagnetic (χ_M ≈ 4 x 10^?4 emu. mol^?1, consistent with their formulation as metallic (A ⁺)₈Tl₁₁ ^7? e^? phases. Factors thought to be responsible for the cluster distortion, the metallic salt characteristics, and the unusual chemistry of thallium am noted.     

Synthesis, crystal structure, and vibrational spectra of MVO(SO4)2 (M = Rb, Cs, or Tl)

A series of MVO(SO₄)₂ vanadium complexes, where M = Rb, Cs, or Tl, were prepared, and their crystal structures and physicochemical properties studied. The rubidium and thallium compounds of this series were found to be isostructural to each other and to crystallize, like KVO(SO₄)₂ and NH₄VO(SO₄)₂, in orthorhombic system (space group P2₁2₁2₁, No. 19, Z = 4) with the unit cell parameters a = 4.9735(2) Å, b=8.7894(4) Å, c = 16.6968(8) Å, V = 729.88 ų (Rb); and a = 4.9636(1) Å, b = 8.7399(2) Å, c = 16.8598(4) Å, V = 731.39 ų (Tl). The cesium compound was found to crystallize in monoclinic system (space group P2₁/a, No. 14-2, Z = 4): a = 10.0968(6) Å, b = 8.9131(4) Å, c = 9.8675(5) Å, β = 114.640(2)°, V = 807.16 ų. The MVO(SO₄)₂ crystal structure is built of VO₆ octahedra, which are linked into layers by bridging SO₄ groups. At the apex of each VO₆ octahedron, there is a short V-O terminal bond having a length of 1.54(1) Å (Rb), 1.57(2) Å (Tl), and 1.52(4) Å (Cs).     

Synthesis,Crystal and Electronic Structure of Layered AMSb Compounds (A = Rb,Cs; M = Zn,Cd)

Synthesis, crystal structure, thermal stability, and electronic band structure of four new metal antimonides AMSb (A = Rb, Cs; M = Zn, Cd) are reported. CsZnSb and RbZnSb crystallize in the hexagonal ZrBeSi structure type, in a P6₃/mmc space group (no. 194, Z = 2) and unit cell dimensions of a = 4.5588(2)/4.5466(4) Å and c = 11.9246(6)/11.0999(10) Å. CsCdSb and RbCdSb crystallize in the tetragonal PbFCl structure type in a P4/nmm space group (no. 129; Z = 2) and unit cell parameters of a = 4.8884(5)/4.8227(3) Å and c = 8.8897(9)/8.5492(7) Å. All four compounds are air- and water-sensitive and are shown through DSC measurements to decompose between 975 K and 1060 K. Analysis of the calculated electronic band structure shows that the Zn-containing antimonides are topologically trivial narrow bandgap semiconductors, whereas Cd-containing compounds exhibit a band inversion along Γ-Z direction.     

Synthesis, structure and bonding of the hypoelectronic cluster compound Sr3Tl5

The Sr3Tl5 phase was prepared by high temperature synthesis techniques through reaction of the high purity elements in the welded Nb tubes.The structure established through X-ray structural analysis shows the compound is a good hypoelectronic trielide example of the Pu3Pd5 structural type in which skeletal electron count is lower than in a traditional Zintl phase(Cmcm,Z = 4;a = 10.604(2) ,b = 8.675(2) ,and c = 10.985(2) ;V = 1010.5(3) 3).The strontium size and the compound’s polarity appear responsible for this thallium phase crystallization in the Pu3Pd5 family type rather than the isoelectronic Sr3In5 version.A first-principle electronic structure calculation(LMTO) demonstrates that the strontium atoms participate substantially in Sr-Tl bonding in the structure.     

Polyatomic clusters of the triel elements. Palladium-centered clusters of thallium in A(8)Tl(11)Pd,A = Cs,Rb, K

Reactions of the elements within welded Ta containers at approximately 600 degrees C followed by slow cooling give new A(8)Tl(11)Pd(x) products from an apparently continuous encapsulation of Pd atoms into the pentacapped trigonal prismatic anions in the isotypic rhombohedral (R3 macro c) A(8)Tl(11) phases. All systems also produce other phases at x < 1 as well, the simplest being the cesium system in which only trigonal Pd(13)Tl(9) is also formed. Cs(8)Tl(11)Pd(0.84(1)) was characterized by single-crystal means as close to the upper x limit in that system (R3 macro c, Z = 6, a = 10.610(1) A, c = 54.683(8) A). The Pd insertion causes an expansion of the D(3) host anion, particularly about the waist, to generate a trigonal bipyramidal PdTl(5) unit (d(Pd-Tl) approximately 2.6-2.8 A) centered within a somewhat larger Tl(6) trigonal prism, the remainder of the Tl(11) cluster. Strong Tl cage bonding is retained. Extended Hückel calculations show significant involvement of all Tl 6s, 6p and Pd 4d, 5s, 5p orbital sets in the central and cage bonding. The last valence electron is considered to be delocalized in a conduction band, as in A(8)Tr(11) examples, rather than occupying an antibonding e' LUMO across a gap of approximately 2.4 eV.     

Synthesis,crystal structure and optical properties of A3Zr2P5S18 (A=Rb,Cs): the first quaternary zirconium thiophosphates

The first quaternary zirconium thiophosphates Rb₃Zr₂P₅S₁₈ (1) and Cs₃Zr₂P₅S₁₈ (2) were synthesized by reacting ZrS₂ with an in situ formed melt of A₂S₃ (A=Rb, Cs), P₂S₅ and S. The compounds are isostructural and crystallize in the monoclinic space group Cc with Z=4. Compound 1 has cell parameters a=9.248(2) Å, b=9.860(2) Å, c=33.622(7) Å and β=94.73(3)° and compound 2 a=9.288(2) Å, b=9.956(2) Å, c=34.061(7) Å and β=94.26(3)°. The structures are composed of a two-dimensional anionic layer [Zr₂P₅S₁₈]³⁻ and intervening alkali cations. Each of the two independent Zr atoms is surrounded by seven S atoms yielding a distorted pentagonal bipyramid. The ZrS₇ polyhedra are interconnected into the final layered anion by [P₂S₇] groups which act in an unusual edge- and corner-sharing mode and by edge-sharing [PS₄] tetrahedra. Compound 2 was characterized with MIR and UV/vis diffuse reflectance spectroscopy.     

New gallium pentaphosphates: AGa2P5O16 (A=Rb,Cs)

Gallium pentaphosphates have been synthesized for the first time. These compounds, RbGa₂P₅O₁₆ and CsGa₂P₅O₁₆, are isotypic to the cesium pentaphosphates CsM₂P₅O₁₆ (M=Fe, V). They crystallize in the noncentrosymmetric Pn space group with a=7.4058(3) Å, b=9.2151(2) Å, c=10.0912(11) Å, β=110.768(8)°, V=643.9(1) Å³ (Z=2) and a=7.462(2) Å, b=9.241(3) Å, c=10.103(2) Å, β=110.731(16)°, V=651.5(3) Å³ (Z=2) for the rubidium and cesium compounds, respectively. The single crystal structure determination shows that the 3D [Ga₂P₅O₁₆]_∞ framework is rather rigid and does not vary significantly whatever M=Fe, V, Ga and A=Rb, Cs. The strongly distorted character of the pentaphosphate unit may be at the origin of strains along the P₅O₁₆ group, which explains the difficulty to stabilize pentaphosphates.     

Synthesis and Crystal Structures of the First Quaternary Tantalum Thiogermanates,ATaGeS5 (A = K,Rb, Cs)

The new quaternary thiogermanates, ATaGeS₅ (A = K, Rb, Cs) were prepared with the use of halide fluxes and the crystal structures of the compounds were determined by single‐crystal X‐ray diffraction methods. The compounds are isostructural and crystallize in space group P\bar{1} of the triclinic system with two formula units in a cell of dimensions: a = 6.937(1) Å, b = 6.950(2) Å, c = 8.844(3) Å, α = 71.07(2)°, β = 78.56(2)°, γ = 75.75(2)°, V = 387.6(2) Å³ for KTaGeS₅; a = 6.996(3) Å, b = 7.033(3) Å, c = 8.985(4) Å, α = 70.33(3)°, β = 78.12(4)°, γ = 75.63(4)°, V = 399.6(3) Å³ for RbTaGeS₅; a = 7.012(4) Å, b = 7.202(3) Å, c = 9.267(5) Å, α = 68.55(3)°, β = 77.27(4)°, γ = 74.75(4)°, V = 416.2(4) Å³ for CsTaGeS₅. The structures of ATaGeS₅ (A = K, Rb, Cs) are comprised of anionic infinite two‐dimensional {}_\infty^2 [TaGeS₅^–] layers separated from one another by alkali metal cations (A⁺). Each layer is made up of tantalum centered sulfur octahedra and pairs of edge‐sharing germanium centered sulfur tetrahedra. The classical charge valence of these compounds should be represented by [A⁺][(Ta⁵⁺)(Ge⁴⁺)(S^2–)₅]. UV/Vis diffuse reflectance measurements indicate that they are semiconductors with optical bandgaps of ca. 2.0 eV.     

On the intersecting tunnel structure of the monophosphates A3(V,W)4O9(PO4)2 with A = Rb,Tl, Cs

The structure determination of a single crystal with composition Rb₃V_1.63W_2.37O₉(PO₄)₂ shows that this phase belongs to the ‘KNbW’ type (K₃Nb₃WO₉(PO₄)₂). This intersecting tunnel structure which consists of octahedral [MO₃]_∞ chains interconnected with ‘MPO₉’ units is closely related to the ‘KVW’-type (K₃V₂W₂O₉(PO₄)₂), and differs only from the latter by the relative orientation of the [MO₃]_∞ chains. In the same way, the X-ray powder diffraction study of the phosphates A₃V₂W₂O₉(PO₄)₂ with A = Rb, Tl, Cs and Rb₃V_xW_{4 − x} O₉(PO₄)₂ (1.5 ≤ x ≤ 3), shows that they all belong to the same structural ‘KNbW’-type and not to the ‘KVW’-type. These results demonstrate the great flexibility of the ‘KNbW’ structure with regard to the ‘KVW’-structure only observed for one compound.     

Synthesis and characterization of A3Na10Sn23 (A = Cs, Rb, K) with a new clathrate-like structure and of the chiral clathrate Rb5Na3Sn25

Four new compounds Cs17.4(1)Na60.6(1)Sn138 (1), Rb19.1(1)Na58.9(1)Sn138 (2), K21.3(1)Na56.7(1)Sn138 (3), and Rb20Na12Sn100 (4) were synthesized by fusion of the corresponding elements. The structures were determined by single-crystal X-ray diffraction. Compounds 1-3 are isostructural and crystallize in a new structure type (rhombohedral, R3m, Z = 1, a = 12.4567(9) A, c = 51.533(3) A for 1; a = 12.465(1) A, c = 51.085(3) A for 2; a = 12.456(2) A, c = 50.559(4) A for 3). The structure contains layers of fused pentagonal dodecahedra of tin that alternate with layers of isolated tin tetrahedra. It is an intergrowth between the structure of clathrate-II (A24Sn136) with the same layers of pentagonal dodecahedra and the Zintl phase ASn with Sn4(4-) tetrahedra. Compound 4 is a new chiral clathrate (cubic, P4(1)32, Z = 1; a = 16.4127(7) A) with stoichiometry that corresponds to an electronically balanced Zintl phase.     

AVNb3Cl11 (A = K, Rb, Cs, Tl): a series of layered vanadium niobium halides based on triangular Nb3 clusters

The first quaternary vanadium niobium compounds containing triangular Nb(3) clusters corresponding to the general formula, AVNb(3)Cl(11) (A = K, Rb, Cs, Tl), have been prepared in sealed quartz tubes from stoichiometric amounts of ACl (A = K, Rb, Cs), or Tl metal, VCl(3), Nb powder, and NbCl(5) heated at 740 degrees C. The compounds crystallize in the orthorhombic space group Pnma (No. 62). The crystal structures of the Rb and Tl members were determined by single-crystal X-ray diffraction techniques. Crystal data: a = 12.771(3) A, b = 6.811(2) A, c = 17.183(3) A, V = 1494.6(1) A(3), and Z = 4 for A = Rb; and a = 12.698(5) A, b = 6.798(3) A, c = 17.145(10) A, V = 1480.0(13) A(3), and Z = 4 for A = Tl. The crystal structure of AVNb(3)Cl(11) consists of triangular Nb(3)Cl(13) clusters (Nb-Nb = 2.826 A) connected to each other via four outer ligands to form infinite chains along the b-axis. The chains are connected by vanadium atoms located in an octahedral environment to form puckered sheets. The A(+) counterions are located between adjacent sheets and coordinate to twelve chlorine ligands in anticubeoctahedral geometry. Electronic structure calculations show bonding orbitals similar to those in Nb(3)Cl(8). Magnetic susceptibility measurements show paramagnetic Curie Weiss behavior.     

A new chalcogenide homologous series A2[M(5+n)Se(9+n)] (A = Rb, Cs; M = Bi, Ag, Cd)

The ternary and quaternary selenides, beta-CsBi3Se5, Rb2CdBi6Se11, CsAg(0.5)Bi(3.5)Se6, CsCdBi3Se6, Rb2Ag(1.5)Bi(7.5)Se13, and Cs2Ag(1.5)Bi(7.5)Se13, are all members of the new homologous series A2[M(5+n)Se(9+n)] and crystallize in structures related to each other in a systematic way; these compounds are mid gap semiconductors and are of interest as thermoelectric materials.     

A2Ca[B4O5(OH)4]2·8H2O(A=Rb,Cs)硼氧酸盐复盐的合成与表征

硼氧酸盐晶体结构复杂，因此出现了许多具有特殊物理性能的晶体功能材料犤１，２犦，尤其是重稀碱金属硼氧酸盐（或复盐），如CsLiB６O１０犤３犦、LiRbB４O７犤４犦和CsB３O５（CBO）犤５犦都是非线性光学材料。一些学者对铷、铯的偏硼氧酸盐、四硼氧酸盐和五硼氧酸盐的合成、性质及晶体结构等进行过研究犤６～９犦。硼氧酸盐复盐，大多为碱金属和碱土金属、碱金属和碱金属及碱土金属和碱土金属的硼氧酸盐犤１０犦，如自然界存在的钠硼解石狖NaCa犤B５O６（OH）６犦·５H２O狚、硼钠镁石狖Na２Mg犤B６O８（OH）４犦２·６H２O…     

A(15)Tl(27) (A = Rb, Cs): A Structural Type Containing Both Isolated Clusters and Condensed Layers Based on the Tl(11) Fragment. Syntheses, Structure, Properties, and Band Structure

The isomorphous title compounds (and the ordered substitutional Rb(14)CsTl(27)) are obtained directly from reactions of the elements in sealed Ta below approximately 330 degrees C. Refinements of single-crystal data for the three established a structure with alternate layers of isolated pentacapped trigonal prismatic Tl(11)(7)(-) (D(3)(h)()) ions and condensed [Tl(16)(8-)] networks that are separated by cations. The condensed layer consists of Tl(11) units that share prismatic edges and are interbridged through waist-capping atoms (Tl(6/2)Tl(3)Tl(2)). (Rb(15)Tl(27): P&sixmacr;2m, Z = 1, a = 10.3248(6) ?, c = 17.558(2) ?.) The rubidium phase is a poor metal (rho(293) approximately 34 &mgr;Omega.cm) and is Pauli-paramagnetic. Extended Hückel band calculations indicate partially filled bands and a non-zero DOS at E(F), consistent with the observed metallic behavior, although appropriate cation tuning or modest anion doping should provide a Zintl phase. The band structure and COOP curves are also used to rationalize the distortion of the Tl(11) unit on condensation and the critical role of the interfragment bonds between waist-capping atoms in stabilizing the layer.     

Die Undecaarsenide A3As11 (A = Rb,Cs) — Synthesen und Kristallstrukturen

Alkaline Metal Arsenides A₃As₁₁ (A = Rb, Cs): Preparation and Crystal Structures Rb₃As₁₁ and Cs₃As₁₁ were synthesized from the elements and the crystal structures of the ordered room temperature form were characterized via single crystal x‐ray studies. In the Zintl phases the As atoms form chiral ufosan‐anions As with As‐As distances ranging from 238 to 248 pm. Like K₃As₁₁ Rb₃As₁₁ crystallizes with the Na₃P₁₁ structure type (orthorhombic, space group Pbcn, a = 1108.2(2), b = 1533.5(3), c = 1060.1(2) pm, Z = 4), whereas the Cs compound (monoclinic, space group C2/c, a = 1324.5(7), b = 1524.5(9), c = 1937.2(11) pm, β = 95.29(1)°, Z = 8) forms a new structure type. The crystallographic relationship between the two structure types and the anion packings in the plastic crystalline high temperature forms are discussed.     

Synthesis and structure of K10Tl7: the first binary trielide containing naked pentagonal bipyramidal Tl7 clusters

The title compound is synthesized by direct fusion of the elements at 400 degrees C followed by annealing at 330 degrees C, quenching to room temperature, and subsequent annealing at 120 and 100 degrees C for days to weeks. The compound crystallizes in the monoclinic space group P21/c (No. 14), with Z = 4, a = 10.132(1) A, b = 22.323(2) A, c = 13.376(1) A, and beta = 93.14(1)degrees, and consists of Tl7(7-) clusters embedded in a matrix of potassium ions. The cluster is an axially compressed pentagonal bipyramid close to D5h symmetry. The apex-apex bond distance (3.462(1) A) is little longer than the bonds in the pentagonal waist (3.183(1)-3.247(1) A). Structurally the compound is not electron-precise: K10Tl7 has three extra electrons per Tl7 cluster and is Pauli paramagnetic (chi300 = 2.25 x 10(-4) emu/mol).     

MZr2（AsO4）3（M=Na,K,Rb,Cs）的水热合成与结构表征

用水热晶化法合成了MZr_2(ASO_4)_3(M=Na,K,Rb,Cs)系列化合物。研究了反应物浓度、配比及不同砷源等水热晶化条件对产物物相的影响。用XRD、IR和Raman光谱对产物进行了表征。4种晶体的振动光谱由钠到铯呈现出规律性变化。