Rubidium Compounds Research Articles

Processing of zinnwaldite waste to obtain Li2CO3

Abstract In this study, Li2CO3 was extracted from a zinnwaldite concentrate with 1.21% Li and 0.84% Rb prepared from zinnwaldite wastes (0.21% Li, 0.20% Rb). These wastes originated from dressing of Sn–W ores, which were mined in the Czech Republic in the past. Processing of the zinnwaldite concentrate consisted of roasting the concentrate with CaCO3 followed by water leaching of the resulting calcines. This method made it possible to extract about 90% of Li as well as Rb. Lithium carbonate products were separated from leach liquor using two different procedures. The first one comprised conversion of the original alkaline leach liquor to carbonated solution by CO2 bubbling, solution purification and Li2CO3 crystallization during water evaporation. The second procedure consisted of lithium solvent extraction from the original leach liquor using LIX 54 and TOPO as an extraction agent followed by stripping with diluted H2SO4, solution purification and lithium carbonate precipitation with K2CO3. Water-washed lithium carbonate salts were produced in both procedures and contained almost 99.5% Li2CO3 with the first method providing higher yield. Mother liquors after Li2CO3 crystallization and/or inorganic phases after lithium solvent extraction are suitable intermediates for production of rubidium compounds, such as Rb2CO3, Rb2SO4 or RbOH.

Synthesis and structure of lithium and rubidium compounds with 2-(diphenylacetyl)-1,3-indanedione

Complexes RbL (I) and [Li2(C2H5OH)L2] (II) (L = C23H15O3) have been synthesized and their crystal structures have been studied. Both compounds have monoclinic crystals with space group P21/c and Z = 4; I: a = 11.632(2) A, b = 15.154(3) A, c = 11.457(2) A, β = 104.34(3)°; II: a = 12.982(3)A, b = 12.083(2) A, c = 25.317(5) A β = 100.11(3)°. In the structure of I, dimeric groups [Rb2O6] with a shared edge are linked by the ligands to give infinite layers perpendicular to the x axis and cavities that form oblong channels. In the structure of II, Li2O7 dimers are formed by vertex sharing. The coordination of one of the lithium atoms (Li(1)) is completed to tetrahedral by the oxygen atom of the ethanol molecule. The structure of II, like that of I, is layered.

Two New Quaternary Thiophosphates with Pseudo One‐dimensional Structures: Syntheses and Crystal Structures of Cs3Sm[PS4]2 and Rb3Sm[PS4]2

AbstractThe new thiophosphates Rb3Sm[PS4]2 and Cs3Sm[PS4]2 were obtained as pale yellow needles using an in‐situ formed thiophosphate flux. Rb3Sm[PS4]2 crystallizes in the space group P21 with a = 9.7061(19) Å, b = 6.7517(14) Å, c = 11.395(2) Å, β = 90.63(3)°, (Z = 2); Cs3Sm[PS4]2 in space group P21/n with a = 15.311(3) Å, b = 6.8762(14) Å, c = 15.352(3) Å, β = 99.49(3)°, (Z = 4). The crystal structures are characterized by the formation of complex anionic chains, $^{1}_{\infty}\rm \{(Sm[PS_{4}]_{2})^{3-}\}$ which run along the [010] direction in both structures. One of the two independent thiophosphate groups connects three Sm3+ cations to form an infinite zigzag like arrangement, while the other acts as a terminal ligand to one Sm3+ions. Such a μ3 or face‐grafting coordination mode of a [PS4]3− anion is not very common. The Sm3+ ions are in bicapped trigonal prismatic chalcogen coordination. The average Sm–S distances within the trigonal prisms are close to 2.88Å, while the bonds to the capping atoms are distinctly longer. The chains are chiral yet their symmetry is close to 21/m. In contrast to the rubidium compound, Cs3Sm[PS4]2 contains both enantiomorphs. In both structures the chains are arranged as a distorted hexagonal rod packing.

Comparative Study of Rubidium and Cesium as Promoters in Carbon-supported Ruthenium Catalysts for Ammonia Synthesis

Sibunit-supported Ru-catalysts promoted with cesium or rubidium compounds have been comparatively studied with XPS. The cesium promoter interacts both with support and with active component. The absence of the promoter–support interaction in the case of rubidium provides a stronger interaction between promoter and active component compared to the cesium-based catalysts. These differences in the promoter–support and promoter–metal interactions are exhibited when a sequence of ruthenium and alkali introduction are changed.

Ge52‐ Zintl Anions: Synthesis and Crystal Structures of [K([2.2.2]‐Crypt)]2Ge5×4NH3 and [Rb([2.2.2]‐Crypt)]2Ge5×4NH3.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Organometallic Compounds of Rubidium and Cesium

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Ge52−Zintl anions: synthesis and crystal structures of [K([2.2.2]-crypt)]2Ge5·4NH3and [Rb([2.2.2]-crypt)]2Ge5·4NH3

The new compounds [K(C18H36N2O6)]2Ge5·4NH3 (1) and [Rb(C18H36N2O6)]2Ge5·4NH3 (2) were prepared by the extraction of a binary phase of the nominal composition KGe1.67 and a ternary phase of the composition Rb0.5Cs0.5Ge2.25 with liquid ammonia in the presence of cryptand [2.2.2]. The resulting crystalline materials were characterized by low temperature X-ray structure analysis. Compounds 1 and 2 contain isolated trigonal-bipyramidal Ge52− cage anions, the symmetries of which were investigated and compared to the previously reported pentagermanide anion. Despite the nearly identical formulae, the two compounds are not isotypic, as the space group type changes from the acentric group P1 (no. 1) for the potassium compound to P (no. 2) for the rubidium compound.

Chain Structures in Alkali Metal Borophosphates: Synthesis and Characterization of K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2

AbstractFor Abstract see ChemInform Abstract in Full Text.

Chain Structures in Alkali Metal Borophosphates: Synthesis and Characterization of K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2

Two new alkali metal borophosphates, K3[BP3O9(OH)3] and Rb3[B2P3O11(OH)2], were synthesized by applying solvothermal techniques using ethanol as solvent. The crystal structures were solved by means of single-crystal X-ray diffraction (K3[BP3O9(OH)3], monoclinic, C2/c (No. 15), a = 2454.6(8) pm, b = 736.3(2) pm, c = 1406.2(4) pm, beta = 118.35(2) degrees , Z = 8; Rb3[B2P3O11(OH)2], monoclinic, P2(1)/c (No. 14), a = 781.6(2) pm, b = 667.3(2) pm, c = 2424.8(5) pm, beta = 92.88(1) degrees , Z = 4). Both crystal structures comprise borophosphate chain anions. While for the rubidium compound a loop-branched chain motif is found as common for most of the chain anions in alkali metal borophosphates, the crystal structure of the potassium phase comprises the first open-branched chain with the highest phosphate content found so far in this group of compounds. Both chain anions are closely related to known anhydrous or hydrated phases, and the structural relations are discussed in terms of how the presence of OH groups and hydrogen bonds as well as number, charge, and size of charge balancing cations influence the 3D structural arrangement. The anionic entities are classified in terms of general principles of structural systematics for borophosphates.

Thiosilicate der Selten‐Erd‐Elemente: III. KLa[SiS4] und RbLa[SiS4] – Ein struktureller Vergleich

AbstractThiosilicates of the Rare‐Earth Elements: III. KLa[SiS4] and RbLa[SiS4] – A Structural ComparisonPale yellow, platelet shaped, air‐ and water resistant single crystals of KLa[SiS4] derived from the reaction of lanthanum (La) and sulfur (S) with silicon disulfide (SiS2) in a molar ratio of 2 : 3 : 1 with an excess of potassium chloride (KCl) as flux and source of potassium ions in evacuated silica ampoules at 850 °C within seven days. The analogous reaction utilizing a melt of rubidium chloride (RbCl) instead also leads to yellow comparable single crystals of RbLa[SiS4]. The potassium lanthanum thiosilicate crystallizes monoclinically with the space group P21/m (a = 653.34(6), b = 657.23(6), c = 867.02(8) pm, β = 107.496(9)°) and two formula units per unit cell, while the rubidium lanthanum thiosilicate has to be assigned orthorhombically with the space group Pnma (a = 1728.4(2), b = 667.23(6), c = 652.89(6) pm) and four formula units in its unit cell. In both compounds the La3+ cations are surrounded by 8+1 sulfide anions in the shape of tricapped trigonal prisms. The Rb+ cations in RbLa[SiS4] show a coordination number of 9+2 relative to the S2− anions, which form pentacapped trigonal prisms about Rb+. This coordination number, however, is apparently too high for the K+ cations in KLa[SiS4], so that they only exhibit a bicapped trigonal prismatic environment built up by eight S2− anions. The isolated thiosilicate tetrahedra [SiS4]4− of the rubidium compound are surrounded by La3+ both edge‐ and face‐capping, but terminal as well as edge‐ and face‐spanning by Rb+. In the potassium compound there is no change for the La3+ environment about the [SiS4]4− tetrahedra, but the K+ cations are only able to attach terminal and via edges. The whole structure is built up by anionic {La[SiS4]}− layers that are separated by the alkali metal cations. In direct comparison the two thiosilicate structures can be regarded as stacking variants.

Cs6[Fe2O6] and Rb4[Fe2O5]: New oxoferrates(III) with edge sharing FeO4 tetrahedra

Abstract The two new oxoferrates(III) Cs6[Fe2O6] and Rb4[Fe2O5] were synthesized at temperatures of 500 and 600 °C via reaction of Fe2O3 with the elemental alkali metals (A) and their hyperoxides AO2 in the form of dark-red crystals. Their crystal structures have both been determined by single crystal X-ray diffraction. The structure of Cs6[Fe2O6] (monoclinic, P21/c, a = 724.6(2), b = 1212.1(5), c = 767.6(3) pm, β = 105.03(4)°, Z = 2, R1 = 0.0272, K6[Mn2O6] structure type) contains isolated bi nuclear anions [O2FeO2FeO2]6- composed of two edge sharing FeO4 tetrahedra, which are also known from the potassium and rubidium compounds A6[Fe2O6] that crystallize in the klassengleiche super group C2/m. Comparable building blocks are connected via common O vertices to form chains 1 ∞[O1/2OFeO2FeOO1/2]4– in the rubidium ferrate(III) Rb4[Fe2O5] (monoclinic, C2/c, a = 711.43(14), b = 1750.0(5), c = 725.3(2) pm, β = 104.72(2)°, Z = 4, R1 = 0.0611). As a consequence of the edge sharing of FeO4 tetrahedra, both compounds show short Fe—Fe distances of 273.3(2) pm in Cs6[Fe2O6] and 265.6(3) pm in Rb4[Fe2O5] respectively. Based on similarities in the packing of the (FeIII/AI) cations, a structural relationship between the two compounds can be derived. The influence of the different counterions on the structure of the oxoferrate units in the phases of general composition A6[Fe2O6] and A4[Fe2O5] is discussed.

Second update on compounds with kröhnkite-type chains

Abstract The crystal structures of five new synthetic double salt dihydrates have been determined from single-crystal X-ray diffraction data. The following three selenate(VI), sulphate(VI) and chromate(VI) compounds all contain kröhnkite-[Na2Cu(SO4)2 · 2 H2O]-type infinite tetrahedral-octahedral chains: K2Zn(SeO4)2 · 2 H2O (a = 5.571(1), b = 6.586(1), c = 7.458(2) Å, α = 111.14(3), β = 96.35(3), γ = 106.15(3)°, V = 238.26(8) Å3, R(F) = 0.037, space group P-1, no. 2, Z = 1), K2Co(SO4)2 · 2 H2O (a = 5.327(1), b = 6.566(1), c = 7.256(2) Å, α = 110.74(3), β = 95.00(3), γ = 107.02(3)°, V = 221.72(8) Å3, R(F) = 0.037, space group P-1, no. 2, Z = 1), Rb2Cd(CrO4)2 · 2 H2O (a = 6.852(1), b = 7.706(2), c = 11.362(2) Å, α = 73.07(3), β = 75.11(3), γ = 69.63(3)°, V = 529.88(18) Å3, R(F) = 0.026, space group P-1, no. 2, Z = 2). The crystal structures of the two remaining compounds, the isotypic dichromates K2Co(Cr2O7)2 · 2 H2O and Cs2Cd(Cr2O7)2 · 2 H2O (a = 6.801(1)/7.368(1), b = 7.723(1)/8.051(2), c = 7.814(1) /8.047(2) Å, α = 89.23(3)/88.68(3), β = 81.05(3)/81.12(3), γ = 64.39(3)/63.81(3)°, V = 364.93(14)/422.66(16) Å3, R(F) = 0.022/0.025, space group P-1, no. 2, Z = 1) are closely related to those of kröhnkite-type compounds; the structure contains Cr2O7 groups assuming the same bridging role that XO4 groups have in kröhnkite-type oxysalts. Both dichromates are isotypic with their K—Zn- and K—Cd-analogues although the hydrogen bonding scheme in Cs2Cd(Cr2O7)2 · 2 H2O is completely different. The atomic arrangements of the five new compounds are described and unusual features are pointed out. Structural relations with other kröhnkite-type and -like minerals and compounds are discussed with respect to our previously proposed classification (Fleck et al., 2002; Fleck and Kolitsch, 2003). The compound Rb2Cd(CrO4)2 · 2 H2O represents both the first kröhnkite-type rubidium compound and the first chromate with structure type D. Cs2Cd(Cr2O7)2 · 2 H2O is the first caesium compound known to contain kröhnkite-like chains.

Alkali‐Metal meta‐Hydroxyphenolates: Syntheses and Crystal Structures from Powder X‐Ray Diffraction

AbstractM[m‐C6H4O(OH)] (M = Li—Cs) have been obtained as highly air‐ and moisture‐sensitive powders from reaction mixtures of the appropriate alkali metals and resorcinol in thf. Both the potassium and rubidium compounds were structurally characterized by means of powder X‐ray diffraction using the Simulated Annealing method and the Rietveld profile refinement technique including C—C/C—O bond distance and C—C—C angle restraints. K[m‐C6H4O(OH)] (orthorhombic P212121) forms infinite alternating chains of meta‐hydroxyphenolate anions connected by K—O bonds and short charge‐assisted hydrogen bonds, thereby generating a three‐dimensional network of corrugated layers similar to the structure of pure resorcinol. The potassium cations are surrounded by a triangle of oxygen and, moreover, coordinated by six adjacent phenylene rings to form a distorted octahedron. The complex crystal structure of Rb[m‐C6H4O(OH)] (monoclinic Pa) is characterized by layers of hydrogen‐bonded meta‐hydroxyphenolate triple units separated by corrugated rubidium layers. The three crystallographically different Rb atoms are coordinated by three, four, and five oxygens with irregular polyhedra, and the rubidiums are also involved in further electrostatic interactions by up to eight phenylene rings.

Alkaline Metal Stannide‐Stannates: ‘Double Salts’ with Zintl Sn and Stannate SnO Anions

AbstractUsing the reduction of tin oxides with the elemental alkaline metals rubidium and cesium, stannide stannates have been synthesized which contain Zintl anions [Sn4]4— (i.e. Sn—I) and isolated oxostannate ions [SnO3]4— (i.e. Sn+II) together with further oxide ions for charge compensation. The crystal structures of the three compounds A23.6Sn7.4O13.2 = A23.6[Sn4][SnO3]3.4[O]3 (A = Rb 1a: monoclinic, P21/c, a = 2174.2(6), b = 1137.0(6), c = 2373.6(6) pm, β = 116.11(2)°, Z = 4, R1 = 0.056; A = Cs 1b: monoclinic, P21/c, a = 2042.6(6), b = 1185.4(3), c = 2481.1(7) pm, β = 97.06(2)°, Z = 4, R1 = 0.075) and Cs48Sn20O21 = Cs48[Sn4]4[SnO3]4[O]7[O2] (2 monoclinic, P2/c, a = 1701.8(3), b = 877.4(2), c = 4556.9(7) pm, β= 101.47(1)°, R1 = 0.093) have been determined on the basis of single crystal data. The transparency of the compounds allowed the recording of raman spectra of the anion [Sn4]4—. The 119Sn Moessbauer spectrum of the rubidium compound shows a singulet in good agreement with RbSn, overlapping a doublet caused by Sn2+ in the asymmetrical environment of the strongly electronegative oxygen ligands of SnO.

Collapse of the antiferromagnetic ground state in the alkali-metal electrosodalites

(Received 24 September 2002; published 26 February 2003) We have studied the collapse under pressure of the antiferromagnetic ground state in F centers contained in alkali-metal-doped sodalites. In agreement with experiment we find that the spin-polarized F-center bands in the sodium-doped sodalite initially narrow with applied pressure. Consequently a high critical pressure for the phase transition from a magnetic insulator to a nonmagnetic metal is predicted (127 GPa). Surprisingly the critical pressures of the potassium- and rubidium-doped sodalites are found to be an order of magnitude lower (20 GPa and 13 GPa, respectively). The collapse of magnetism is found to occur when the unoccupied p states of the alkali-metal atoms hybridize with the F-center bands. The low critical pressure for the potassium and rubidium compounds can therefore be explained by the smaller energy difference between the unoccupied p states and the occupied states compared to sodium. Furthermore we find the sodalite lattice to be softer than previously reported, which is explained by a simple structural model.

Crystal structure analysis and extremely long-living light-induced metastable states in RbY[Fe(CN)5NO]2·10H2O and CsY[Fe(CN)5NO]2·10H2O

Abstract Crystal structures of both isostructural com-pounds were solved from single crystal X-ray diffraction data (space group P21/n; Z = 4; Rb-compound: a = 9.812(1) Å, b = 25.793(3) Å, c = 11.777(2) Å, β = 104.68(1)°, R gt(F) = 0.0458, wR ref(F 2) = 0.0918; Cs-compound: a = 9.9058(8) Å, b = 25.919(2) Å, c = 11.883(1) Å,β = 105.542(7)o, Rgt(F) = 0.0450,wRref(F2) = 0.0951. The main structural feature is the nitrosylpentacyanoferrate(II)-complex [Fe(CN)5NO]2–. The iron atoms are coordinated to five cyanide and one nitrosyl ligand. The coordination polyhedron of the Y3+ cation is a distorted tetragonal antiprism built up from three nitrogen atoms of three complexes and five water molecules. Both rubidium and cesium ions are surrounded by seven cyanide groups of five complexes and one water molecule to form a distorted bicapped trigonal prism. One metastable state (SI) can be excited by irradiation with light in the spectral range of 400–500 nm at temperatures below 180 K. The radiationless thermal decay is detected by Differential Scanning Calorimetry by heating above T = 180 K. Evaluating the exothermal heat flow using the Arrhenius law yields an activation energy of EA = 0.64(2) eV and a frequency factor of Z = 20(8)·1012s–1 for the rubidium compound and EA = 0.56(2) eV, Z = 30(8)·1010s–1 for the cesium compound. The contribution of the cations on the decay temperature of the metastable states is discussed on the basis of the atomic distances and coordinations.

Enthalpies of Phase Transitions and Heat Capacity of TbCl3 and Compounds Formed in TbCl3–MCl Systems (M=K, Rb, Cs)

The molar enthalpies of the solid–solid and solid–liquid phase transitions were determined by differential scanning calorimetry for pure TbCl3 and KTb2Cl7, RbTb2Cl7, CsTb2Cl7, K3TbCl6, Rb3TbCl6 and Cs3TbCl6 compounds. Both types of compounds, i.e. M3TbCl6 and MTb2Cl7 (M=K, Rb, Cs) melt congruently and show additionally a solid–solid phase transition with a corresponding enthalpy Δtrs H 0 of 6.1, 7.6 and 7.0 kJ mol–1 for potassium, rubidium and caesium M3TbCl6 compounds andΔtrs H 0 of 17.1 (rubidium) and of 12.1 and 10.9 kJ mol–1 (caesium) for MTb2Cl7 compounds, respectively. The enthalpies of fusion were measured for all the above compounds with the exception of Rb3TbCl6 and Cs3TbCl6. The heat capacities of the solid and liquid compounds have been determined by differential scanning calorimetry (DSC) in the temperature range 300–1100 K. The experimental heat capacity strongly increases in the vicinity of a phase transition, but varies smoothly in the temperature ranges excluding these transformations. C p data were fitted by an equation, which provided a satisfactory representation up to the temperatures of C p discontinuity. The measured heat capacities were checked for consistency by calculating the enthalpy of formation of the liquid phase, which had been previously measured. The results obtained agreed satisfactorily with these experimental data.

Partial Oxidation of Propane over Rubidium-Promoted MoO3/SiO2 Catalyst

Silica-supported Rb2MoO4 and rubidium-promoted MoO3 were used as catalysts for the partial oxidation of propane in a fixed-bed continuous-flow reactor at 770–823 K using N2O as oxidant. The main hydrocarbon products of the reaction were propylene, ethylene, propanal and methane. Addition of various compounds of rubidium to the MoO3/SiO2 greatly enhanced the conversion of propane and promoted the formation of propanal at the expense of ethylene and propylene. The highest yield for the production of this compound was found over Rb2MoO4/SiO2 catalyst.

Crystal Growth and Optical Properties of the Polar Hydrated Pentaborates Rb[B5O6(OH)4] . 2H2O and NH4[B5O6(OH)4] . 2H2O and Structure Redetermination of the Ammonium Compound

Large single crystals of the polar, hydrated pentaborates Me[B5O6(OH)4]�2H2O (Me = Rb, NH4) were grown from aqueous solutions. The structure of NH4[B5O6(OH)4] . 2H2O was redetermined and proved to be orthorhombic (space group Aba2 (No. 41) with a = 11.3192(7) Å, b = 11.0261(8) Å, c = 9.2316(5) Å, V = 1152.2(1) Å3, Dx = 1.569 Mgm-3, Z = 4, M = 272.15 gmol-1, R(F) = 0.0369 for 1266 unique reflections (I >= 4 σ (I)), isomorphous with the potassium and rubidium compounds. Refractive indices between 365 nm and 1100 nm as well as unpolarized absorption spectra of [B5O6(OH)4] . 2H2O and NH4[B5O6(OH)4] . 2H2O were determined and phase-matching curves for second-harmonic generation were calculated. Both compounds allow type I and type II phase-matching at wavelengths from about 450 nm to the near infrared region.

Structural Diversity in the Solid-State Structures of the Rubidium and Cesium Salts of 2,6-Dimesitylphenylphosphane.

A coordination environment reminiscent of a paddle-wheel is exhibited by aryl groups about one of the two cesium ions in CsP(H)Dmp (Dmp=2,6-dimesitylphenyl; structure depicted on the right), which has now been synthesized and is found to exhibit Cs+ {Cs2 [P(H)Dmp]3 }- contact ion pairs in the solid state. In contrast, the analogous rubidium compound displays a Rb4 P4 cube as the central structural motif.