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.     

Neue Tetrapnictidotitanate(IV): Na3M3[TiX4] mit M  Na/Sr,Na/Eu und X  P,As

New Tetrapnictidotitanates(IV): Na₃M₃[TiX₄] with M ? Na/Sr, Na/Eu and X ? P, As The four novel tetrapnictidotitanates(IV) Na₄Sr₂TiP₄, Na₄Sr₂TiAs₄, Na_4.3Eu_1.7TiP₄ and Na_4.3Eu_1.7TiAs₄ were prepared from the binary pnictides NaX, M₃X, M′X (X ? P, As and M′ ? Sr, Eu) and elementary titanium in tantalum ampoules. The air and moisture sensitive transition metal compounds form dark red hexagonal crystals. They are semiconductors with E_g = 1.8eV (Sr) and E_g = 1.3eV (Eu), respectively. The compounds are isotypic with Na₆ZnO₄ (space group P6₃mc (no. 186); hP22; Z = 2; Na₄Sr₂TiP₄; a = 936.8(1) pm, c = 740.5(1) pm; Na₄Sr₂TiAs₄: a = 958.2(1) pm, c = 757.1(1) pm; Na_4.3Eu_1.7TiP₄: a = 929.9(2) pm, c = 732.0(2) pm; Na_4.3Eu_1.7TiAs₄: a = 953.9(1) pm, c = 749.5(1) pm). Main structural units are polar oriented [TiP₄]^8? and [TiAs₄]^8? tetrahedral anions with d (Ti? P) = 240.2(3) pm and d (Ti? As) = 248.6(3) pm.     

Magnetische Wechselwirkungen in Inselstrukturen ternärer Cobaltchalkogenide. Die Spinstrukturen von Na6CoS4 und Na6CoSe4

Magnetic Interactions in Ternary Cobalt Chalcogenides containing Isolated Tetrahedral Cobalt Anionic Groups. The Spin Structures of Na₆CoS₄ and Na₆CoSe₄ The sodium cobalt chalcogenides Na₆CoS₄ and Na₆CoSe₄ are characterized by isolated [CoX₄]-units. Despite the large distances of more than 6 Å between the cobalt ions magnetic inter-actions at low temperatures lead to threedimensionally ordered spin structures, that were determined from neutron diffraction experiments. The magnetic structure can be described in the Shubnicov group P_2abc2₁ with a unit cell that is four times as large as the crystallographic cell. The magnetic moments of both compounds correspond to the value expected for three unpaired electrons per Co²⁺ ion.     

Darstellung,Struktur und magnetisches Verhalten von Alkali-metallmanganchalkogeniden A6MnX4 mit A Na oder K und X S,Se oder Te

Inhaltsübersicht. Die Verbindungen Na₆MnS₄, Na₆MnSe₄, Na₆MnTe₄, K₆MnS₄, K₆MnSe₄ und K₆MnTe₄ wurden durch Umsetzungen von Alkalimetallcarbonaten mit Chalkogen und Mangan bzw. Mangancarbonat in einem mit Chalkogen beladenen Wasserstoffstrom erhalten. Röntgenstrukturuntersuchungen an Einkristallen ergaben, daß alle sechs Verbindungen isotyp kristallisieren (Na₆ZnO₄-Typ, Raumgruppe P6₃mc). Als charakteristische Baugruppen treten “isolierte” tetraedrische [MnX₄]-Einheiten auf. Die Temperaturabhängigkeiten der magnetischen Suszeptibilitäten führen zu einem Curie-WeissVerhalten. Erst bei tiefen Temperaturen treten offensichtlich antiferromagnetische Kopplungen auf. Dabei sind die Wechselwirkungen in den Tellurverbindungen stärker als in den Schwefelverbindungen und in den Kaliumverbindungen stärker als in den Natriumverbindungen ausgeprägt. Synthesis, Structure, and Magnetic Properties of Alkali Metal Manganese Chalcogenides A₆MnX₄ with A Na or K and X S, Se or Te The compounds Na₆MnS₄, Na₆MnSe₄, Na₆MnTe₄, K₆MnS₄, K₆MnSe₄ and K₆MnTe₄ were synthesized by the reaction of alkali metal carbonates with chalcogen and Mn or MnCO₃ in a stream of hydrogen charged with chalcogen. Structural investigations on single crystals show that all six compounds crystallize in isotypic atomic arrangements (Na₆ZnO₄-type, space group P6₃mc), which are characterized by isolated [MnX₄] tetrahedra. The magnetic susceptibilities show Curie-Weiss behaviour. At low temperatures there are obviously antiferromagnetic interactions increasing from the sulfides to the tellurides and from the sodium compounds to the potassium compounds.     

Enhanced Zintl anions by carbon doping in Al-Na clusters and new magic structure Al6Na4C

This article investigated the low-energy structures of Al₆Na _mC (m = 2, 4, 6, 8) clusters and their electronic structures by using genetic algorithm combined with density functional theory and configuration interaction methods. The computations show that the C atoms prefer sitting at the center, whereas the Na atoms tend to locate at the outside of the clusters. The valence molecular orbitals (MOs) agree well with the prediction of the jellium model. The stronger attraction of the central carbon to the valence electrons will depress the potential energies locally, which makes the 2S level go obviously lower and the 2P and 1D orbitals form a sub-band. The 26 valence electrons in Al₆Na₄C form closed 1S²1P⁶2S²1D¹⁰2P⁶ shells and correspond to a new magic structure. The MOs and electron localization function show that the sodium cores are exposed at the outside of the valence electrons and form naked cations. The contraction of the valence electrons because of the carbon doping enhances the charges on the Al₆C moieties, and the Na⁺ cores on the peripheries are ionically bonded to the Zintl anions (Al₆C)^q−. The Al₆Na₄C has a tetrahedral structure with symmetry T_d, and it may be used as building blocks to synthesize Zintl solid.     

Über die quasi-binären Systeme NaNO2/Na2O und NaCN/Na2O. Phasendiagramme und Natrium-Ionenleitung in Na3O(NO2) und Na3O(CN)

On the Quasi-Binary Systems NaNO₂/Na₂O and NaCN/Na₂O. Phase Diagrams and Sodium Ion Conductivity of Na₃O(NO₂) and Na₃O(CN) Measurements of the electrical conductivities of Na₃O(NO₂) and Na₃O(CN) show sharp increases in conductivity at temperatures between 200° and 250°C, According to the phase diagrams of the quasi-binary systems NaNO₂/Na₂O and NaCN/Na₂O this is not an effect established by fusion. It seems to be a consequence of a “melting” of the sodium sublattice or the rotational disorder of complex anions.     

Na5FeS4 – das erste Thioferrat(III) mit diskreten tetraedrischen Anionen

Na₅FeS₄ — the First Thioferrate(III) with Discrete Tetrahedral Anions Ruby red crystals of Na₅FeS₄ were obtained by reacting a stoichiometric mixture of Na₂S, Fe, and S at 970 K. The compound is orthorhombic, space group Pbca, with a = 11.947(5), b = 7.091(3), c = 21.54(1) Å, Z = 8. The crystal structure was determined from single crystal diffractometer data. The atomic arrangement – which corresponds to that of Na₅GaO₄ [1] – is characterized by discrete tetrahedral [FeS₄] groups, separated from each other by Na⁺ cations. Measurements of the magnetic susceptibilities show coupling effects between Fe³⁺ ions below 28 K. At higher temperatures a Curie-Weiss behaviour indicates a high-spin-state of the Fe³⁺ ions. Relationships between the interatomic distances and the magnetic moments in alkali thioferrates are discussed.     

Phasenbeziehungen und Natriumionenleitung im quasi-binären System Na2SiF6/Na3AlF6

Phase Relations and Sodium Ion Conductivity within the Quasi-binary System Na₂SiF₆/Na₂AIF₆ . The phase diagram of the Na₂SiF₆/Na₃AlF₆ system has been determined by means of x-ray powder diffraction, thermal analysis and conductivity measurements in the sub-solidus region. Na₃AlF₆ accomodates up to 73 mol.-% Na₂SiF₆ maintaining the crystal structure type. The sodium ion conductivity increases by about five orders of magnitude upon doping Na₃AlF₆ with Na₂SiF₆.     

Die kubischen Phasen Na16(ARb6)Sb7, Verbindungen mit den Anionen A = Rb−, Na−, Au−, I−

The Cubic Phases Na₁₆(ARb₆)Sb₇, Compounds with the Anions A = Rb^?, Na^?, Au^?, I^? The novel compounds Na₁₆(ARb₆)Sb₇ have been synthesized from the elements in sealed Nb ampoules at 873 K (A = Rb) and 823 K (A = I, Na, Au). They form brittle cuboctahedra (silver metallic; A = Rb) and irregular polyhedra (silver metallic lustre; A = Na, I; golden metallic lustre; A = Au). They rapidly decompose in moist air to gray products. Their crystal structures have been determined by single crystal X-ray crystallography (A = Rb: a = 1565.8(2) pm; A = I: a = 1563.3(2) pm; A = Na: a = 1562.6(2) pm; A = Au: a = 1560.7(2) pm). They crystallize cubically in the space group Fm3 m (no. 225) with Z = 4 formula units and are isotypic with Sc₁₁Ir₄. The compounds are ZINTL phases and their structures can be described as an eightfold defect variant of the Li₃Bi type of structure (cF128-8; a = 2a′(Li₃Bi)). The Sb atoms form a network of cuboctahedra, centered alternatingly by a SbNa₈ cube or a ARb₆ octahedron. Main structural features are the anions A^? within the Rb₆ octahedron. Supporting the existence of A^? are the isotypical compounds with the more common anion forming elements (A = Au, I), as well as electrostatic potential considerations together with calculations of the volume increments. The semiconducting properties (E_g = 0.33 eV) of Na₁₆(RbRb₆)Sb₇, as well as the diamagnetism χ_mol = ?508 × 10^?6 cm³ mol^?1, are in accordance with those to be expected from the Zintl concept.     

Zur Kenntnis des Natrium-tetrahydroxoaluminat-chlorids Na2[Al(OH)4]Cl

On the Sodium Tetrahydroxoaluminate Chloride Na₂[Al(OH)₄]Cl The hitherto unknown compound Na₂[Al(OH)₄]Cl was prepared by crystallisation from a NaCl containing sodium aluminate solution. According to the X-ray single crystal investigation (tetragonal, space group P4/nmm, a = 7.541 Å, c = 5.059 Å, Z = 2) the compound represents the first example of a crystalline hydroxoaluminate with monomeric [Al(OH)₄]^? anions. Cl^? shows a quadratic anti prismatic coordination to 4 Na⁺ and over hydrogen bonds to 4 O^2? while Na⁺ is octahedrally coordinated by 4 O^2? and 2 Cl^? (axial). The results of the crystal structure analysis are confirmed by ²⁷Al and ²³Na MAS NMR investigations. Na₂[Al(OH)₄]Cl decomposes at about 200°C without intermediates under formation of β-NaAlO₂ and NaCl.     

Über Oxobismutate. Zur Kenntnis von Na3BiO4 und Na3SbO4

On oxobismuthates. The compounds Na₃BiO₄ and Na₂SbO₄ Na₃BiO₄ crystallizes monoclinic in C⁴_2h; a = 5.87₁ b = 6.69⁶, c = 5.65₀ Å and β = 109,8° with Z = 2. We have a variant of the NaCl type, forming chains ¹_∞[BiO_4/2+2/1] along [001]. The MADELUNG part of lattice energy (MAPLE) of Na₃BiO₄ and different other structure models are calculated und discussed. Na₃SbO₄[a = 5.79₅, b = 6.59₅, c = 5.41₈ Å, β = 109.4°] is isotypic with Na₃BiO₄.     

Na4SeO5, ein neues Pentaoxoselenat(VI) – Synthese,Charakterisierung und Vergleich mit isotypem Na4MoO5

Na₄SeO₅, a Novel Pentaoxoselenate(VI) – Synthesis, Charakterisation, and Comparison with Na₄MoO₅ Na₄SeO₅ was prepared by high pressure solid state reaction at 500 °C and at a hydrostatic pressure of 2.5 Gpa from a mixture of Na₂O and Na₂SeO₄ in silver crucibles and Na₄MoO₅ by solid state reaction at 450 °C from a mixture of Na₂O and MoO₃. The crystal structures of both new compounds were solved and refined using X‐ray powder methods (Profilematching Na₄SeO₅: P1, a = 988.3(1), b = 988.4(1), c = 558.6(1) pm, α = 96.25(1)°, β = 96.24(1)°, γ = 113.41(1)°, R_p = 0.0783, R_wp = 0.1037. Profilematching Na₄MoO₅: P1, a = 999.5(1), b = 1002.0(1), c = 565.1(1) pm, α = 96.54(1)°, β = 96.29(1)°, γ = 113.35(1)°, R_p = 0.0623, R_wp = 0.0867). Both compounds contain novel XO₅^4– anions of approximately tetragonal pyramidal shape. The crystal structures are consistent with spectroscopic data (IR, Raman).     

Die Systeme K2NaAlF6/Na2SO4 und K2NaAlF6/K2SO4 Phasendiagramme und Alkaliionenleitung

On the Systems K₂NaAlF₆/Na₂SO₄ and K₂NaAlF₆/K₂SO₄: Phase Diagrams and Alkali Ion Conductivity The phase diagrams of the K₂NaAlF₆/Na₂SO₄ and K₂NaAlF₆/K₂SO₄ systems have been determined by means of thermal, x-ray powder and electrochemical methods in the solidus-liquidus and the sub-solidus region, as well. At the optimum combination of parameters, the alkaliion conductivity increased by about three orders of magnitude upon doping K₂NaAlF₆ with Na₂SO₄ and/or K₂SO₄.     

ChemInform Abstract: Isomorphous Substitution of Rare‐Earth Elements in Lacunary Apatite Pb8Na2(PO4)6.

Pb_8‐xLn_xNa₂(PO₄)₆ (x = 0—2.0; Ln: Y, La, Pr—Ho, Tm—Yb) with void structural channels are prepared by solid state reaction of PbO, Na₂CO₃, (NH₄)₂HPO₄, and Ln oxides (Al₂O₃ crucible, 800 °C, 2—10 d).     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. XIII. Über die Verbindungen Na6Ge2S6 · 4 CH3OH und Na6Ge2Se6 · 4 CH3OH

Glass Formation and Properties of Chalcogenide Systems. XIII. On the Compounds Na₆Ge₂S₆ · 4 CH₃OH and Na₆Ge₂Se₆ · 4 CH₃OH The glasses Ge₂S₃ and Ge₂Se₃ are soluble in solutions of Na₂S or Na₂Se in CH₃OH forming Na₆Ge₂S₆ · 4 CH₃OH and Na₆Ge₂Se₆ · 4 CH₃OH. On heating the CH₃OH-free substances are formed. From the i.r. and Raman spectra can de seen that the structure of the ions Ge₂S, Ge₂Se, P₂S₆^4?, and of Si₂Cl₆ is of the same type. The formation of the compounds can be regarded as a chemical proof for the existence of [Ge₂S₆] and [Ge₂Se₆] units as structural groups in the glasses Ge₂S₃ and Ge₂Se₃.     

Zur Synthese und Kristallstruktur der ternären Carbide Na2PdC2 und Na2PtC2

Syntheses and Crystal Structures of Ternary Carbides Na₂PdC₂ and Na₂PtC₂ Na₂PdC₂ and Na₂PtC₂ were synthesized by the reaction of sodium carbide with palladium and platinum respectively. The crystal structures could be solved from X-ray powder diffraction data (space group: P3 m1, Z = 1). Both compounds crystallize in a new structure type with [M(C₂)_2/2^2?] chains (M?Pd, Pt) as the characteristic structural unit. The existence of a C? C triple bond was confirmed by Raman spectroscopy.     

Na3Fe2S4, ein Thioferrat mit gemischt valenter sk∞/1[FeS2]-Kette

Na₃Fe₂S₄ has been prepared from Na₂S, S and Fe. It crystallizes in space group Pnma,a=6.6333 (5) Å,b=10.675 (1) Å,c=10.677 (2) Å,Z=4. The crystal structure, as determined from single crystal four-circle diffractometer data (R=2.8%), consists of sk/1[FeS₂]-chains formed by slightly distorted edge sharing [FeS₄]-tetrahedra, the iron atoms having a formal valency of +2.5. The sodium ions are approximately octahedrally coordinated. Exposed to air, Na₃Fe₂S₄ readily takes up water to form a hydrate by a pertially topochemical reaction.

     

Die Kryolithstruktur von Na3ScF6 und die Oktaederkippung in isostrukturellen Natriumhexafluorometallaten Na3MF6

The Cryolite Structure of Na₃ScF₆ and the Tilting of Octahedra in Isostructural Sodium Hexafluorometallates Na₃MF₆ X-ray studies at single crystals of Na₃ScF₆ confirmed the monoclinic cryolite type structure of this compound: a = 559.5, b = 580.2, c = 811.6 pm, β = 90.72°, Z = 2, space group P2₁/n; R1 = 0.021 for 512 symmetry independent reflections. The octahedra of [ScF₆] (average Sc? F = 200.7 pm), as well as those of [NaF₆] (Na1? F = 229.1 pm) linked to them, are titled by about 20° with respect to the axes of the perovskite-like pseudocell. This tilting of octahedra is discussed in comparison with other cryolites and with orthorhombic perovskites NaMF₃; there results a correlation between tilt angle and tolerance factor t ? 0.88 of these compounds, the [NaF₈] coordination of which invariably exhibits a constant mean value of Na2? F = 231.5 ± 1 pm for the four shortest distances.     

Nonanatrium-bis(hexahydroxoaluminat)-trihydroxid-hexahydrat (Na9[Al(OH)6]2(OH)3 · 6H2O) – Kristallstruktur,NMR-Spektroskopie und thermisches Verhalten

Nonasodium Bis(hexahydroxoaluminate) Trihydroxide Hexahydrate (Na₉[Al(OH)₆]₂(OH)₃ · 6H₂O) – Crystal Structure, NMR Spectroscopy and Thermal Behaviour The crystal structure of the nonasodium bis(hexahydroxoaluminate) trihydroxide hexahydrate Na₉[Al(OH)₆]₂(OH)₃ · 6H₂O (4.5 Na₂O Al₂O₃ · 13.5 H₂O) (up to now described as 3 Na₂O · Al₂O₃ · 6H₂O, 4Na₂O · Al₂O₃ · 13 H₂O and [3 Na₂O · Al₂O₃ · 6H₂O] [xNaOH · yH₂O], respectively) was solved. The X-ray single crystal diffraction analysis (triclinic, space group P1 , a = 8.694(1) Å, b = 11.344(2) Å, c = 11.636(3) Å, α = 74.29(2)°, β = 87.43(2)°, γ = 70.66(2)°, Z = 2) results in a structure, consisting of monomeric [Al(OH)₆]^3? aluminate anions, which are connected by NaO₆ octahedra groups. Furthermore the structure contains both, two hydroxide anions only surrounded by water of crystallization and OH groups of [Al(OH)₆]^3? aluminate anions and a hydroxide anion involved in three NaO₆ coordination octahedra directly and moreover connected with a water molecule by hydrogen bonding. The results of ²⁷Al and ²³Na-MAS-NMR investigations, the thermal behaviour of the compound and possible relations between the crystal structure and the conditions of coordination in the corresponding sodium aluminate solution are discussed as well.     

Über Glasbildung und Eigenschaften von Chalkogenidsystemen. XXXIII. [1] Kondensierte Thio- und Selenohypodigermanate und -silicate Na8M4X10 (MSi,Ge) und Na4Ge4X8 (XS,Se)

About Glass Formation and Properties of Chalcogenide Systems. XXXIII. Condensed Thio- and Selenohypodigermanates and -silicates Na₈M₄X₁₀ (M?Si, Ge) and Na₄Ge₄X₈ (X?S, Se) The formation of the compounds Na₈Si₄X₁₀ and Na₈Ge₄X₁₀ (X?S, Se) is reported prepared by reaction of Ge₂S₃ or Ge₂Se₃ with Na₂S or Na₂Se, respectively, in CH₃OH utilizing a mole ratio of 1 to 2 or in the case of the Si compounds by synthesis from the elements. Applying the mole ratio Ge₂X₃:Na₂X = 1 the compounds Na₄Ge₄X₈ (X?S, Se) are obtained. The anion constitution is discussed in relation with cryoscopic mole weight measurements in Glauber-salt melts.