Une nouvelle famille structurale: Les oxydes Ln4−2xBa2+2xZn2−xO10−2x (Ln = La,Nd)

Two original compounds, Ln_4?2xBa_2+2xZn_2?xO_10?2x, were isolated for Ln = La, Nd and 0 ≤ x ≤ 0.25. These oxides are tetragonal with a and c parameters close to 6.91 and 11.59 Å, respectively, for lanthanum, and 6.75 and 11.54 Å for neodymium. The structure of these phases was determined from X-ray powder patterns in the most symmetric space group, $\text{I}\text{4}\text{mcm}$, using Patterson and Fourier functions for x = 0. The structure should be compared to that of copper oxides La_4?2xBa_2+2xCu_2?xO_10?2x: it is built up of identical Ln₂O₅ layers formed from face- and edge-sharing LnO₈ polyhedra, between which Ba²⁺ and Zn²⁺ ions are inserted. Contrary to the copper compounds, two successive Ln₂O₅ layers are rotated by 90°, involving a doubling of c. The result for Zn²⁺ is tetrahedral coordination, while the coordination of Ba²⁺ becomes a bicapped antiprism.     

Zur Kenntnis von Ba10Fe8Pt2Cl2O25

About Ba₁₀Fe₈Pt₂Cl₂O₂₅ The crystal structure of Ba₁₀Fe₈Pt₂Cl₂O₂₅ has been solved by direct methods, using intensity data collected by means of an automatic diffractometer (MoKα). It crystallizes in the hexagonal space group D–P6₃/mmc: a = 5.8034(4) Å, c = 24.997(5) Å, Z = 1. Fe³⁺ ions occur in both octahedral and tetrahedral coordination. Two types of Ba²⁺ ions are formed, with ten and twelve neighbouring atoms. The structure consists of plane connected FeO₆ and PtO₆ octahedra which are connected by corner shared FeO₄ tetrahedra.     

Synthese und Kristallstruktur von Ba25Cu142+Cu43+Zn4O49

Synthesis and Crystal Structure of Ba₂₅Cu₁₄²⁺Cu₄³⁺Zn₄O₄₉ Single crystals of Ba₂₅Cu₁₄²⁺Cu₄³⁺Zn₄O₄₉ were prepared with solid state and flux reactions. X-ray investigations show tetragonal symmetry, space group D⁷_4th–P4/nmm, a = 18.2146, c = 9.3230 Å, Z = 2. The hitherto unknown structure type shows copper in square pyramids and planar polygones, connected to six member rings or Cu₅O₂₀ groups. Slightly bent Cu₅O₁₂ groups produced by edge connection of five CuO₄ polygones are connected with ZnO₄ tetrahedra forming Cu₅Zn₄O₂₀ units. The complicated structure is shown step by step.     

Ln2BaZnO5 and Ln2BaZn1−xCuxO5: A series of zinc oxides with zinc in a pyramidal coordination

A series of zinc oxides Ln₂BaZnO₅ has been synthesized for Ln = Sm, Eu, Gd, Dy, Ho, and Y. Theses phases are orthorhombic and isostructural with the copper compounds Ln₂BaCuO₅ previously described, as shown from the structural study of one member Y₂BaZnO₅. In this structure, whose framework is built up from edge- and face-sharing LnO₇ polyhedra, the Zn²⁺ ions exhibit an unusual pyramidal coordination ZnO₅. The solid solution Y₂BaZn_1?xCu_xO₅ has been studied by infrared spectroscopy and electron spin resonance (ESR). The distorted square-based pyramidal configuration of Zn²⁺ and Cu²⁺ is confirmed. The ESR spectra of diluted samples exhibit a hyperfine structure and are typical of individual Cu(II) ions. For higher Cu(II) contents, they exhibit an anisotropic broad signal which is interpreted in terms of CuCu interactions.     

Ein Beitrag über Ba3Pt4HgO11: Das erste Erdkalimetall-Oxoplatinat(II,V)/Oxomercurat

A Contribution on Ba₃Pt₄HgO₁₁: The First Alkaline-Earth Oxoplatinate(II,V)/Oxomercurate Single crystals of Ba₃Pt₄HgO₁₁ were prepared by oxygen high pressure technique (4 200–3 600 bar) and investigated by X-ray methods. It crystallizes with hexagonal symmetry, space group D? P6 2c, a = 6.021, c = 17.374 Å, Z = 2. Ba₃Pt₄HgO₁₁ represents a new structure type, showing structural relationships to Ba₂Hg₃Pd₇O₁₄ and to the precious metal 6L-perovskites. The Hg²⁺ ions show dumb-bell like coordination, Pt²⁺ a square-planar surrounding and Pt⁵⁺ face shared double octahedra.     

Synthese und Kristallstruktur von Ba6Lu4Zn10O22 mit [OBa6]-Oktaedern

On the Synthesis and Crystal Structure of Ba₆Lu₄Zn₁₀O₂₂ with [OBa₆] Octahedra Single crystals of Ba₆Lu₄Zn₁₀O₂₂ have been prepared by high temperature reactions and investigated by X-ray techniques. This compound is isotypic to Ba₃In₂Zn₅O₁₁ and the first member of the Rare Earth elements. Ba₆Lu₄Zn₁₀O₂₂ crystallizes with cubic symmetry, space group T-F4 3m, a = 13.452(1) Å and Z = 4. Zn²⁺ shows a tetrahedral, Lu³⁺ an octahedral and Ba²⁺ a three-fold capped trigonal prismatic coordination by O^2?. The ZnO₄ tetrahedra and LuO₆ octahedra are forming macro polyhedra of the type Zn₁₀O₂₀ and Lu₄O₁₆. A discussion is given for the Ba₆O₃₃ and Ba₆O₄₂ groups.     

Diffraction and DAFS Studies of a Ba4(BaxPt1−x)Pt2O9Twinned Crystal, a Member of the Bap(BaxPt1−x)Ptp−2O3p−3Series

Crystallographic studies of the Ba–Pt–O system have been undertaken using X-ray and electron diffraction techniques. The system is described by means of a Ba_p(Ba_xPt²⁺_1−x)Pt⁴⁺_p−2O_3p−3formula which corresponds to a BaO₃hexagonal based framework with Pt chains, whereprepresents the oxygen deficiency and the presence of both Pt⁴⁺and Pt²⁺cations in the compounds, andxa possible substitution of Pt²⁺by Ba²⁺in trigonal prismatic sites. The structure of a Ba₄(Ba_0.04Pt²⁺_0.96)Pt⁴⁺₂O₉crystal has been solved by using 5548 X-ray difraction reflections collected on a twinned crystal. Refinements were performed with two distinct models: an “average”P321 space group and an “orthorhombic”C2 space group with cell parametersa=17.460(4) Å,b=10.085(2) Å,c=8.614(3) Å. In this structure, two Pt⁴⁺and one Pt²⁺cations are distributed over four Ba planes and form chains along thecaxis, consisting of two face-sharing Pt⁴⁺O₆octahedra connected with one Pt²⁺O₆trigonal prism. A lattice misfit occurs between the rigid barium lattice and the PtO₃chains, giving rise to a composite structure. Twinning and domain configurations are described and taken into account in the refinement. This twinning is related to the presence of Pt²⁺cations, whose positions break the threefold axis symmetry. A diffraction anomalous fine structure (DAFS) study was also performed on this twinned single crystal. Anomalous scattering factorsf′ andf″ for platinum in this crystal were refined near the L_IIIPt absorption edge. They confirm the weak barium occupancy of the trigonal prismataic site and the Pt⁴⁺valence of the octahedral sites. Reflection overlaps, due to twinning, flatten the DAFS sensitivity to Pt atoms in the prismatic sites and did not allow their clear valence determination, but Pt–O bond lengths agree with the presence of Pt²⁺cations at the center of prismatic faces. Electron diffraction patterns of powders having slightly different composition show a continuous evolution of incommensurate Bragg peaks and a weak correlation between the PtO₃chains. They also confirm the composite nature and the one-dimensionality of the Ba_p(Ba_xPt²⁺_1−x)Pt⁴⁺_p−2O_3p−3series, which can produce highly anisotropic physical properties.     

Sr4PbPt4O11, the first platinum oxide containing Pt2 ions

We report the synthesis and crystal structure of the new compound Sr₄PbPt₄O₁₁, containing platinum in highly unusual square pyramidal coordination. The crystals were obtained in molten lead oxide. The structure was solved by X-ray single crystal diffraction techniques on a twinned sample, the final R factors are R=0.0260 and wR=0.0262. The symmetry is triclinic, space group P1¯, with , , , α=90.421(3)°, β=89.773(8)°, γ=90.140(9)° and Z=2. The structure is built from dumbell-shaped Pt₂O₉ entities formed by a dinuclear metal-metal bonded Pt₂⁶⁺ ion with asymmetric environments of the two Pt atoms, classical PtO₄ square plane and unusual PtO₅ square pyramid. Successive Pt₂O₉ entities deduced from 90° rotations are connected through the oxygens of the PtO₄ basal squares to form [Pt₄O₁₀⁸⁻]_∞ columns further connected through Pb²⁺ and Sr²⁺ ions. Raman spectroscopy confirmed the peculiar platinum coordination environment.     

Zur Kristallchemie eines neuen Barium-Lanthanoid-Oxozinkats: Ba2Er2Zn8O13

On the Crystal Chemistry of a New Barium Rare-Earth Oxozincate: Ba₂Er₂Zn₈O₁₃ High temperature reactions led to single crystals of Ba₂Er₂Zn₈O₁₃. It crystallizes with orthorhombic symmetry, space group C¹²_2v? Cmc2₁, a = 6.276, b = 10.871, c = 10.195 Å, Z = 2. The hitherto unknown crystal structure shows Zn²⁺ with tetrahedral, Er³⁺ octahedral and Ba²⁺ cuboctahedral coordination by O^2?. It will be shown that parts of the [Zn₈O₁₃] network are fragments of the ZnO structure showing O^2? within a tetrahedral zinc coordination. A deficit of two O^2? ions per unit cell is focused on two point positions.     

A structural model for barium platinum oxide,Ba3Pt2O7

A single crystal study of Ba₃Pt₂O₇ shows that the structure tolerates a variable composition which can be written Ba₃Pt_2+xO_7+2x. The crystal studied has a hexagonal cell of dimensions a = 10.108 ± 0.006 Å and c = 8.638 ± 0.009 Å, and a probable space group $\text{P}\text{6}\text{2c, Z = 4}$. The density determined by water displacement is 7.99 g/cm³; the theoretical density for Ba₃Pt₂O₇ is 7.94 g/cm³. The structure was determined from the set of 401 observed independent reflections obtained from 5189 reflections measured by automated counter methods. Refinement on F was carried to a conventional R of 8.0%. The structure has barium-oxygen layers with an essentially four-layer stacking sequence of the double hexagonal (ABAB) type. Platinum is found mainly in face-sharing octahedra, but is also distributed over some sites in which the coordination is nearly square planar and other sites in which the coordination is trigonal prismatic with three PtO bond lengths of 2.00 Å and three long PtO distances of 2.65 Å. The platinum with planar coordination is 0.08 Å from the plane of the four oxygen atoms.     

Isolierte quadratische Koordination von Pt2+ in BaNd2PtO5

Isolated Square-Planar Coordinated Pt²⁺ Inside of BaNd₂PtO₅ Single crystals of the hitherto unknown compound BaNd₂PtO₅ were prepared and examined by X-ray technique. The compound crystallizes with tetragonal symmetry D? P4 b2; a = 6.7569(6) and c = 5.9119(13) Å; Z = 2. The structure is discussed in respect of the isolated square-planare coordination of Pt²⁺ ions and its relation with other planar coordinated platinum of oxocompounds.     

Zur Kristallchemie der Oxorhenate

On the Crystal Chemistry of Oxorhenates The review deals with the crystal chemistry of oxorhenates. In contrast to the crystal chemistry of the lately discussed rhodium oxides rhenium shows many and diverse coordination. Examples are square planar polygons, trigonal bipyramids and tetrahedral as well as octahedral surroundings by oxygen. Starting with the oxides ReO₂, Re₂O₇, Re_1,16O₃, Re₃O₁₀ and ReO₃ it will be shown that oxorhenates form isolated tetrahedra, octahedra, Re₂O₁₀‐ and Re₂O₉‐groups. The polyhedra of rhenium are isolated to each other or arranged in one‐dimensional chains, in two dimensional nets and three‐dimensional networks. Rhenium adapts the crystal structures of perowskites, fluorites, pyrochlores, rutiles and stacking variants of the perowskites. Special features are mercuro‐oxorhenates (HgReO₄, Hg₂ReO₅, Hg₅Re₂O₁₀) showing – Hg⁺‐Hg⁺ – groups and Rare Earth‐Oxorhenates (Ln₂ReO₅, Ln₃Re₂O₉, Ln₅Re₂O₁₂) revealing clearly visible Re‐Re – interactions. PbRe₂O₈ and BiReO₄ are remarkable because of one sided open polyhedra, due to the lone pair activity. The positions of lone pairs (e^2? – point charge) are verified by calculations of Madelung parts of lattice energy.     

Zur Kristallchemie von Ba3In2Zn5O11. Ein tOxoindat/zinkatsol;zinkat mit Zn10O20- und In4O16-Makropolyedern und erstmals O2− in tetraedrischer Koordination durch Zn2+

On the Crystal Structure of Ba₃In₂Zn₅O₁₁. An Oxoindate/zincatesol;zincate with Zn₁₀O₂₀ and In₄O₁₆ Macropolyhedra with Zn²⁺ in Tetrahedral Coordination by O^2? Ba₃In₂Zn₅O₁₁ was prepared for the first time by a flux technique and investigated by single crystal X-ray work. It crystallizes with cubic symmetry, space group T-F4 3m, a = 13.3588 Å, Z = 8. Zn²⁺ show tetrahedral coordination by O^2?, forming Zn₁₀O₂₀ macropolyhedra. In addition the nZn/Osol;O part of the crystal structure is made up of Zn₁₀O₂₀ parts. Edge connection of four InO₆ octahedra results in In₄O₁₆ groups. The crystal structure will be shown and discussed.     

Zur Kenntnis eines Oxoargentato(I)-aurats(III): Ba4AgAuO6

On the Oxoargentato(I)-aurat(III): Ba₄AgAuO₆ The hitherto unknown compound Ba₄AgAuO₆ was prepared by oxidizing Ba/Au/Ag alloy with BaO₂/Ba(OH)₂ mixture in closed Ag tubes. X-ray single crystal investigation led to orthorhombic symmetry space group D-Cmcm; a = 13.275; b = 5.782; c = 11.396 Å; Z = 4. Ba₄AgAuO₆ shows distorted pentagonal bipyramidal polyhedra around Ba²⁺ and square planar AuO₄ polygones. Ag⁺ shows an unusual 2 + 2 coordination by O^2?.     

Ein Beitrag über CuPrMo2O8 und CuTbMo2O8

A Contribution on CuPrMo₂O₈ and CuTbMo₂O₈ Single crystals of (I): CuPrMo₂O₈ and (II): CuTbMo₂O₈ were prepared by solid state reactions in closed copper tubes. They crystallize with orthorhombic symmetry, space group D-Pbca, (I): a = 10.4114, b = 9.8917, c = 14.8287 Å, (II): a = 10.2243, b = 9.7385, c = 14.6000, Z = 8. Both compounds are isotypic to CuYMo₂O₈, showing isolated MoO₄ tetrahedra, square antiprismatic coordination of Ln³⁺ and Cu⁺ besides one edge of an O^2? triangle. Calculations of the coulombterm of lattice energy support the oxidation state Cu²⁺ in combination with mixed valences of Mo⁶⁺ and Mo⁵⁺ on the molybdenum point positions.     

Zwei neue Verbindungen mit Zink in tetragonal pyramidaler Koordination: BaZnDy2O5 und Ba1,25ZnHo2O5,25 (Ba5Zn4Ho8O21)

New Compounds with Zinc in Square Pyramidal Coordination: BaZnDy₂O₅ and Ba_1.25ZnHo₂O_5.25 (Ba₅Zn₄Ho₈O₂₁). Single crystals of (I): BaZnDy₂O₅ and (II): Ba₅Zn₄Ho₈O₂₁ were prepared by high temperature reactions and investigated by X-ray technique. (I) belongs to the BaCuLn₂O₅ type, space group D-Pbnm; a = 7.084; b = 12.368; c = 5.728 Å, Z = 4. (II) is isotypic to Ba₅Mn₄Ln₈O₂₁, space group C-I4/m; a = 13.779; c = 5.707 Å, Z = 2. The two different structure types are caused by the small difference in the composition of 0.25 BaO. Analogies and differences will be discussed. In addition the lattice constants of powder samples of Ba₅Zn₄Ln₈O₂₁ (Ln = Eu, Gd, Dy, Ho, Er and Y) are given.     

Ein neues Alkali-Erdalkalimetall-Kupfer-Oxovanadat: Kba3Ca4Cu3V7O28

A new Alkaline-Alkaline-Earth-Copper-Oxovanadate: Kba₃Ca₄Cu₃V₇O₂₈ . Single crystals of Kba₃Ca₄Cu₃V₇O₂₈ were prepared by solid state reactions below the melting point of the reaction mixture. It crystallizes with hexagonal symmetry, space group C?P6₃mc, a=11.160, c=12.428 Å, Z=2. Kba₃Ca₄Cu₃V₇O₂₈ represents a new structure type with special coordination polyhedra around Ba²⁺, trigonal prisms and octahedra around Ca²⁺ and Cu²⁺ inside square pyramids. The crystal structure will be shown and discussed.     

Über Oxocuprate. XI. Zur Kenntnis von Ba3Cu2O4Cl2

On Osocuprates. XI. Ba₃Cu₂O₄Cl₂ A new oxohalogenocuprat, Ba₃Cu₂O₄Cl₂ mas prepared and investigated by X-ray single crystal methods. The hitherto unknown compound has orthorhombic symmetry (Space group: D_2h⁵—Pmma; a = 6.653, b = 6.000, c = 10.563 Å). It shows angled chains of O^2?-squares around Cu²⁺. One of the Cu²⁺ positions is completed by Cl^minus; to a tetragonal pyramid. The coordination polyhedrals of Ba_I–III and the connection with the Cu/O-chains are described and discussed.     

Direct titrimetric microdetermination of uranium

Summary Direct titrimetric method for the estimation of uranium(VI) in the range of 0.7 to 76 mg is performed by decomposing and oxidising the complex, {U(VI)O₂ · U(V)O₂ · Fe(CN)₆}, with ceric sulphate. The mixed valency state in the above mentioned complex has been confirmed by magnetic measurements, the isolated complex being paramagnetic. Na⁺, K⁺, Cs⁺, Ca²⁺, Sr²⁺, Mg²⁺, Be²⁺, Pd²⁺, La³⁺, Ir³⁺, Ru³⁺, and Te⁴⁺ do not interfere but Ag⁺, Tl⁺, Cu²⁺, Ba²⁺, CO²⁺, Ni²⁺, Zn²⁺, Pb²⁺, Hg²⁺, Sn²⁺, Bi³⁺, Au³⁺, Rh³⁺, Sb³⁺, In³⁺, Ti³⁺, Th⁴⁺, Zr⁴⁺, Pt⁴⁺, V⁵⁺, Se⁶⁺, MO⁶⁺, and Os⁸⁺ do.

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Zusammenfassung Die Bestimmung von Uran(VI) in der Größenordnung von 0,7 bis 76 mg erfolgt durch Zersetzung und Oxydation des Komplexes U(VI)O₂ · U(V)O₂ · · Fe(CN)₆ mit Cer(IV) sulfat. Die zweierlei Wertigkeitsstufen in diesem paramagnetischen Komplex wurden durch magnetische Messungen bestätigt. Na⁺, K⁺, Cs⁺, Ca²⁺, Sr²⁺, Mg²⁺, Be²⁺, Pd²⁺, La³⁺, Ir³⁺, Ru³⁺, and Te⁴⁺ stören nicht; hingegen stören Ag⁺, Tl⁺, Cu²⁺,Ba ²⁺, CO²⁺, Ni²⁺, Zn²⁺, Pb²⁺, Hg²⁺, Sn²⁺, Bi³⁺, Au³⁺, Rh³⁺, Sb³⁺, In³⁺, Ti³⁺, Th⁴⁺, Zr⁴⁺, Pt⁴⁺, V⁵⁺, Se⁶⁺, MO⁶⁺, and Os⁸⁺.

     

Cd2Cu(PO4)2

During an investigation of the insufficiently known system M1O–M2O–X₂O₅–H₂O (M1 = Cd²⁺, Sr²⁺ and Ba²⁺; M2 = Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺ and Mg²⁺; X = P⁵⁺, As⁵⁺ and V⁵⁺), single crystals of the novel compound dicadmium copper(II) bis[phosphate(V)], Cd₂Cu(PO₄)₂, were obtained. This compound belongs to a small group of compounds adopting a Cu₃(PO₄)₂‐type structure and having the general formula M1₂M2(XO₄)₂ (M1/M2 = Cd²⁺, Cu²⁺, Mg²⁺ and Zn²⁺; X = As⁵⁺, P⁵⁺ and V⁵⁺). The crystal structure is characterized by the interconnection of infinite [Cu(PO₄)₂]_n chains and [Cd₂O₁₀]_n double chains, both extending along the a axis. Exceptional characteristics of this structure are its novel chemical composition and the occurrence of double chains of CdO₆ polyhedra that were not found in related structures. In contrast to the isomorphous compounds, where the M1 cations are coordinated by five O atoms, the Cd atom is coordinated by six. The dissimilarity in the geometry of M1 coordination between Cd₂Cu(PO₄)₂ and the isomorphous compounds is mostly due to the larger ionic radius of the Cd cation in comparison with the Cu, Mg and Zn cations. Sharing a common edge, two CdO₆ polyhedra form Cd₂O₁₀ dimers. Each such dimer is bonded to another dimer sharing common vertices, forming [Cd₂O₁₀]_n double chains in the [100] direction. The Cu atoms, located on an inversion centre (site symmetry ), form isolated CuO₄ squares interconnected by PO₄ tetrahedra, forming [Cu(PO₄)₂]_n chains similar to those found in related structures. Conversely, the [Cd₂O₁₀]_n double chains, which were not found in related structures, are an exclusive feature of this structure.