Zur Kenntnis von K4PbO4 und Rb4PbO4

On K₄PbO₄ and Rb₄PbO₄ For the first time single crystals of K₄[PbO₄] have been prepared by heating K₄PbO₃ in O₂. The structure has been refined [K₄[PbO₄]: 3029 I₀(hkl), four circle diffractometer PW 1100, ω-scan, MoKα, R = 6.73%, R_w = 6.64%, P1 ; a = 658.62(15), b = 658.41(12), c = 986.64(21) pm, α = 79.74(2)°, β = 108.45(2)°, γ = 112.49(2)°, d_x = 3.79 g · cm^?3, d_pyk = 3.78 g · cm^?3, Z = 2; Rb₄[PbO₄]: a = 686.94(18), b = 684.43(18), c = 1020.73(21) pm, α = 79.28(2)°, β = 108.40(2)°, γ = 113.02(2)°, d_x = 4.87 g · cm^?3, d_pyk = 4.85 g · cm^?3, Z = 2, (from Rb₂PbO₃ and Rb₂O)]. Both compounds are isotypic with K₄SnO₄. The Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated.     

Über ternäre Oxide des Bleis: Zur Kenntnis von Na6PbO4

On Ternary Oxides of Lead. The Na₆PbO₄ New obtained Na₆PbO₄ (colourless to pale yellow), is due to single crystal datas cubic, I43m, with a=11,0₁ Å and Z=8. Parameters were refined by least-squares (705 h01–h51, Mo–K_α) Ra=0.082, R′=0.091 (Parameters see text). In an ordered derivative of Na₂O-structure, there are according to [O′′Na₄Na₄] [O′(PbO₃″′)₄] “isolated” Pb₄O₁₃-groups, which are connected with each other by Na′ and Na″. The MADELUNG part of lattice energy (MAPLE) is calculated and discussed.     

Zur Kenntnis ternärer Oxide des Bleis: Über Na2PbO2

On Ternary Oxides of Lead. The Na₆PbO₅ Na₆PbO₅ (pale yellow) crystallizes orthorhombic in Cmcm with a=10.6₈, b=5.70₉, c=10.9₉, å; Z=1. Parameters were refined by least-squares (479 hkO–hk7, MO–K_α) R=0.112₄, R′=0.116, (parameters see text). Isolated PbO₅ groups of pseudotetragonal pyramids lend Pb⁴⁺ Coordination Number (CN) 5. Along [100] and [010] the pyramids are equivalent orientated, but along [001] alternately twisted by 180°. Na+ occupies holes between O^2?, leading to CN 6 (Na″+) and Na″′⁺ and CN 4 (Na′⁺). The MADELUNG part of lattice energy (MAPLE) is calculated and discussed.     

Zur Kenntnis ternärer Oxide des Bleis1: Über Na2PbO2

On Ternary Oxides Lead. The Na₂PbO₂ New obtained colourless single crystals of Na₂PbO₂ are orthorhombic [Pbcn; a=16.8₃, b=6.93₉, c=5.88₂ Å, Z=8]. Parameters were refined by least-squares [370 h01–h31; Mo– K_α, R=0.108] (parameters see text). Na₂PbO₂ shows a layer-lattice: perpendicular to (100) there follow layers with the sequence (Na_0,5Pb_0,5)ONaO(Na_0,5Pb_0,5Pb_0,5)…?(Na_0,5Pb_0,5)ONaO(Na_0,5Pb_0,5). The connexion of neighboured cation-layers of this type are connected in a way, that the lone-paired electrons of Pb²⁺ are bridged with Na+. The MADELUNG part of lattice energie (MAPLE) is calculated and discussed.     

Die Kristallstruktur des Natriumorthogermanats,Na4GeO4

The crystal structure of the title compound has been determined from single crystal X-ray diffraction data and refined toR=0.125. The unit cell is triclinic, space group P, (No. 2),a=5.688(1),b=5.701(1),c=8.583(1) Å, =81.32(1), =71.50(1), =67.95(1)° andZ=2. The structure consists of isolated [GeO₄] tetrahedra linked together by four- and five-coordinate sodium atoms. Na₄GeO₄ is isostructural with Na₄CoO₄ (which has been described to be non-centrosymmetric and for which a centrosymmetric model is presented), K₄GeO₄, K₄SnO₄ and K₄PbO₄.

     

Darstellung und Kristallstruktur von K4[SnO3]

Preparation and Crystal Structure of K₄[SnO₃] K₄[SnO₃] crystallizes with the K₄[PbO₃] structure in the orthorhombic spacegroup Pbca (No. 61) with the lattice constants a = 652.2(3) pm, b = 1 112.1(5) pm and c = 1 893.7(7) pm. In the structure isolated ψ-tetrahedral anions [Sn^IIO₃]^4? are arranged in layers perpendicular [001]. The structure of K₄[SnO₃] will be compared with those of stannates and plumbates of composition A₄[M^IIO₃] (A = Na, K, Rb, Cs) and with the known potassium stannates(II).     

K4PbO4 und K4GeO4 – ein Vergleich

K₄PbO₄ and K₄GeO₄ — a Comparison The question is: In which case are two compounds isotypic? The structures of K₄PbO₄ and K₄GeO₄ are derived using ?Schlegelprojektionen”? (reduced atomic distances and angles) and ?Erweiterte Schlegeldiagramme”? of the anions: O1, O2, O3 and O4. The difference is pointed out and discussed. For both compounds the interatomic distances are listed.     

Das erste Oxoplumbat(II) mit Inselstruktur: K4[PbO3]

The First Oxoplumdat(II) with Island Structure: K₄[PbO₃] For the first time K₄PbO₃ has been prepared as colourless powder and transparent single crystals, respectively. K₄PbO₃ crystalizes orthorhombic, space group Pbca-D, a = 6.54₃, b = 11.40₅, c = 18.70₉ Å, Z = 8. d_rö = 3.99, d_pyk = 3.98. For 1040 independent reflextions we find R = 9.6%. Parameters see text. There are isolated PbO₃ groups, with symmetry approximately C_3v, which are ordered in a very complicated manner and connected by K⁺ ions forming layers. The Madelung Part of the Lattice Energy, MAPLE, and Effectiv Coordination Numbers, ECoN, these by means of Mean Fiktive Ionic Radii, MEFIR, are calculated and discussed.     

Korrektur zur Kristallstruktur von „Cs4PbO3”︁ und die Strukturverwandtschaft zwischen den Modifikationen von Cs4PbO4

Correction of the Crystal Structure of “Cs₄PbO₃” and the Structural Relationship between the Modifications of Cs₄PbO₄ The compound that has been described as Cs₄PbO₃ really is Cs₄PbO₄. It does not crystallize in the space group P2₁, as assumed, but in P2₁/c. The observed fictitiuous violation of the extinction law for the c glide plane is due to twinning. The structure was refined using the original data as well as new data from an untwinned crystal. The denomination β-Cs₄PbO₄ is used to distinguish this structure from another known modification (α-Cs₄PbO₄). Both structures, α-Cs₄PbO₄ and β-Cs₄PbO₄, can be derived from the sphere packing of γ-plutonium when certain voids in its packing are occupied with oxygen atoms.     

Solid‐Liquid Equilibria in the Quinary Na+, K+//Cl−, SO2−4, B4O2−7‐H2O System at 298 K

The solid‐liquid equilibria in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K had been studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the quinary system were measured experimentally. Based on the experimental data, the dry‐salt phase diagram and water content diagram of the quinary system were constructed, respectively. In the equilibrium diagram of the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K, there are five invariant points F1, F2, F3, F4 and F5; eleven univariant curves E1F1, E2F2, E3F3, E4F5, E5F2, E6F4, E7F5, F1F4, F2F4 F1F3 and F3F5, and seven fields of crystallization saturated with Na₂B₄O₇ corresponding to Na₂SO₄, Na₂SO₄·10H₂O, Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄, K₂B₄O₇·4H₂O, NaCl and KCl. The experimental results show that Na₂SO₄·3K₂SO₄ (Gla), K₂SO₄ and K₂B₄O₇·4H₂O have bigger crystallization fields than other salts in the quinary system Na⁺, K⁺//Cl^?, SO^2?₄, B₄O^2?₇‐H₂O at 298 K.     

Five-component reciprocal systems Na,K∥Cl,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript> and Na,K∥F,CO<Subscript>3</Subscript>,MoO<Subscript>4</Subscript>,WO<Subscript>4</Subscript>

Five-component reciprocal systems Na,K∥Cl,CO₃,MoO₄,WO₄ and Na,K∥F,CO₃,MO₄,WO₄ have been studied by differential thermal analysis (DTA) and X-ray powder diffraction (XPD). The systems have been triangulated to phase simplexes. The main reciprocal and complex-formation reactions have been revealed. The stability of [Na,K]₂CO₃, Na₂[Mo,W]O₄, and K₂[Mo,W]O₄ binary solid solutions and the nonexistence of quintuple invariant points in the title systems have been verified.     

Comparison of the performances of Ti/SnO2-Sb, Ti/SnO2-Sb/PbO2, and Nb/BDD anodes on electrochemical degradation of azo dye

In this paper, the preparation conditions of antimony-doped SnO₂ and PbO₂ electrode were optimized for the degradation activity of AO7 dye solution. The results showed that when the doping content of Sb is 8 mol %(SnO₂-Sb(0.08)), the SnO₂ electrode exhibited best activities for the decolorization and mineralization of AO7. The concentration of NaF in electroplating solution had a noticeable effect on PbO₂ electrode for the decolorization of AO7 solution, but little influence on the COD removal rate. The anodic stability tests showed that the electrode prepared in the solution containing 0.10 g l⁻¹ NaF (PbO₂-F(0.10)) was best for environmental application. The comparison of SnO₂-Sb(0.08), PbO₂-F(0.10) and Boron-doped Diamond (BDD) electrodes revealed that a more rapid decolorization rate was obtained on SnO₂-Sb(0.08) and PbO₂-F(0.10) electrodes in dilute AO7 solutions, while higher COD removal rate of concentrated AO7 solutions was on BDD and SnO₂-Sb(0.08) electrodes. The effect of concentration of Na₂SO₄ on the degradation rate of AO7 was very notable on BDD electrode for its highest overpotential of oxygen evolution reaction. In the chloride-containing medium, the decolorization was accelerated greatly but the completed mineralization of AO7 was inhibited with the increasing of chloride ions concentration when these high-overvoltage anodes were used Published in Russian in Elektrokhimiya, 2008, vol. 44, No. 7, pp. 865–875. The text was submitted by the authors in English.     

Zur Konstitution von ‚KPbO2’︁

On the Constitution of ‘KPbO₂’ Transparent, orangered single crystals of K₂Pb₂O₄ have been obtained by heating mixtures of K₂O₂ and PbO (K:Pb = 1:1) [Ag-cylinders, 560°C, 40 d, after cooling (15°C/h)]. The space group is P1 , a = 1295.94(9), b = 753.35(7), c = 697.12(8) pm, α = 118.00(1)°, β = 106.15(1)°, γ = 93.44(1)°, Z = 4, d_x = 6.573 und d_pyk = 6.54 g · cm³. The structure is characterized by rutilanalogous chains of edge-connected [PbO₆] octahedra along [001] according to [PbO_4/2O_2/1] = PbO₄. On both sides of such a chain there are respectively three O^2?, which belong to two octahedra, alternating capped with Pb²⁺ or not capped, corresponding to [PbO₄]Pb₂[PbO₄]□₂… = Pb₂O₄. Those capped chains are held together by K(1)…K(4), each of them with C.N. 6. The order of the chains corresponds to the motive of a closest packing. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, are calculated and discussed.     

Über die Magnetischen Eigenschaften der Cobaltate Na6CoS4, Na6CoSe4 und K6CoS4

Magnetic Properties of the Cobaltates Na₆CoS₄, Na₆CoSe₄, and K₆CoS₄ The alkali metal cobalt chalcogenides Na₆CoS₄, Na₆CoSe₄, and K₆CoS₄ crystallize in the space group P6₃mc with Z = 4. The structure is characterized by isolated [CoX₄]-tetrahedra. The magnetic susceptibilities show Curie-Weiss behaviour. The deviations at low temperatures are caused by antiferromagnetic interactions. The magnetic moments are discussed with regard to ligand-field parameters.     

Untersuchungen an Systemen aus Salzen und gemischten Lösungsmitteln. VI. Das Verhalten des reziproken Salzpaares Na2SO4 + 2 KCl ⇌ K2SO4+2 NaCl in Methanol-Wasser-Mischungen

The solubility isotherms of the system Na₂SO₄? K₂SO₄? CH₃OH? H₂O at 25,40 and 55°C and the solubilities in the system of the metathetic salt reaction Na₂SO₄+ + 2KCl ? K₂SO₄ + 2NaCl in methanol-water mixtures at 10 and 25°C have been determined and the nature of the solid phases established. The addition of methanol causes an enlargement of the sulphatic existence fields. A flow sheet for the industrial application of the results is communicated.     

Préparation,Proprietés Cristallographiques et Magnétiques des Phases K3XO4 (XV,Cr, Mn)

Preparation and Crystallographic and Magnetic Properties of the Phases K₃XO₄ (X?V, Cr, Mn) The compounds K₃VO₄, K₃CrO₄ and K₃MnO₄ occur with two allotropic forms, which are isostructural with K₃Cr(O₂)₄ and Na₂CaSiO₄. Magnetic measurements confirm the oxidation state +V for both chromium and manganese.     

Neues über Oxogermanate. 1. Zur Kenntnis von K4GeO4

News on Oxogermanates. 1. On K₄GeO₄ For the first time single crystals of K₄GeO₄ have been prepared by heating KO_0.46 and GeO₂. The structure has been refined. K₄GeO₄: 2565 I₀(hkl), four circle diffractometer PW 1100, ω-scan, AgKα, R = 0.0826, R_w = 0.0837, P1 ; a = 640.56(35), b = 633.87(34), c = 933.68(45) pm; α = 80.26(5)°, β = 107.58(5)°, γ = 113.63(4)°; d_x = 2.94 g/cm³; d_pyk = 2.91 g/cm³; Z = 2. K₄GeO₄ is isotypic with K₄SnO₄. There is, however, an essential difference of the C.P. (Coordination Polyhedra) with respect to K4 and O4. The Effective Coordination Numbers, ECoN, the Mean Fictive Ionic Radii, MEFIR, and the Madelung Part of Lattic Energy, MAPLE, are calculated.     

Über quaternäre Oxoplumbate(IV). Zur Kenntnis von Rb3NaPbO4

On Quaternary Oxoplumbates(IV). On Rb₃NaPbO₄ For the first time, Rb₃NaPbO₄ has been prepared by annealing mixtures of Na₂PbO₃ and RbO_0.84 with Rb:Na:Pb = 4:2:1 [nonhermetic Ag-cylinders, sealed under vacuum in Duran-glass ampoule, 480°C, 180 d (single crystals)]. The colourless crystals are of squatted shape. The structure determination [2943 symmetry independent hkl, four-circle-diffractometer PW 1100 (Fa. Philips), ω-2Θ-scan, AgKα, R = 8.64%, R_W = 6.59%, absorption not considered] confirms the space group P2₁/c with a = 1101.79(26), b = 662.66(11), c = 1115.01(30) pm, β 112.027(21)°. The structure is characterized by isolated [PbO₄]-tetrahedra and [Na₂O₆]-tetrahedra-doubletts, C.N. 5 and 7 for Rb⁺. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Effective Ionic Radii, MEFIR, are calculated.     

Über Oxoplumbate(IV): Ba2PbO4

On Oxoplumbates(IV): Ba₂PbO₄ For the first time single crystals of Ba₂PbO₄ have been prepared by exchange reaction [BaPbO₃: Li₂O₂ = 2:4; Ag-cylinder, Argon, quartz ampoule, 800°C, 30 d]. The structure determination [137 I₀(hkl), fourcircle diffractometer PW 1100 (Fa. Philips), MoKα, R = 5.04%, R_w = 4.93%] confirms the space group I4/mmm with a = 430.08 and c = 1325.63 pm (K₂NiF₄-type, parameters s. text).     

Na12Ge17: A Compound with the Zintl Anions [Ge4]4— and [Ge9]4— — Synthesis,Crystal Structure,and Raman Spectrum

Na₁₂Ge₁₇ is prepared from the elements at 1025 K in sealed niobium ampoules. The crystal structure reinvestigation reveals a doubling of the unit cell (space group:P2₁/c; a = 22.117(3)Å, b = 12.803(3)Å, c = 41.557(6)Å, β = 91.31(2)°, Z = 16; Pearson code: mP464), furthermore, weak superstructure reflections indicate an even larger C‐centred monoclinic cell. The characteristic structural units are the isolated cluster anions [Ge₉]^4— and [Ge₄]^4— in ratio 1:2, respectively. The crystal structure represents a hierarchical cluster replacement structure of the hexagonal Laves phase MgZn₂ in which the Mg and Zn atoms are replaced by the Ge₉ and Ge₄ units, respectively. The Raman spectrum of Na₁₂Ge₁₇ exhibits the characteristic breathing modes of the constituent cluster anions at ν = 274 cm^—1 ([Ge₉]^4—) and ν = 222 cm^—1 ([Ge₄]^4—) which may be used for identification of these clusters in solid phases and in solutions. Raman spectra further prove that Na₁₂Ge₁₇ is partial soluble both in ethylenediamine and liquid ammonia. The solution and the solid extract contain solely [Ge₉]^4—. The remaining insoluble residue is Na₄Ge₄. By heating the solvate Na₄Ge₉(NH₃)_n releases NH₃ and decomposes irreversibly at 742 K, yielding Na₁₂Ge₁₇ and Ge.