Über Perowskitphasen des Systems Ba2Y0,67U1−xWxO6

On Perovskite Phases of the System Ba₂Y_0,67U_1?xW_xO₆ A solid solution series is formed between the polymorphic perovskites Ba₂Y_0.67UO₆ and Ba₂Y_0.67WO₆ (cubic: a = 8.37₂ Å; hexagonal: a = 4× 5.88₁ Å and c = 4× 7.77₈ Å). The structure is cubic between x = 0.1 and 0.99 and for x > 0.95 hexagonal as well. Strong deviations from the ideal behaviour are detectabel with spectroscopic methods. The shape of the UO₆ and WO₆ octahedrons experiences only minor changes within the series.     

Über Geordnete Perowskite mit Kationenfehlstellen. II. Der Ersatz von UVI durch NbV in Ba2Gd0,67□0,33UO6

On Ordered Perovskites with Cationic Vacancies. II. The Incorporation of Nb^V in Ba₂Gd_0,67□_0,33UO₆ In Ba₂Gd_0.67□_0.33UO₆ a complete substitution of U^VI by Nb^V is possible by filling the cationic vacancies (x-phase: Ba₂Gd_0.67+0.33xU_1?xNb_xO₆). For the y-Phase (Ba₂Gd_0.67U_1?yNb_yO_6?0.5y) solid solutions are formed only for y ? 0.5. The properties of both phases are studied by x-ray and spectroscopic methods. In Ba₂GdNbO₆ – in contrary to the complete ordered Ba₂GdTaO₆ – the order of gadolinium and niobium id partial.     

Über die Polymorphie der Perowskite Ba2SE0,67WVIO6. II. Die Systeme Ba2Nd0,67(1−x) Y0,67xWO6 und Ba2Nd0,67W1−xUxO6

Polymorphism of Perovskite Compounds Ba₂SE_0.67W^VIO₆. II. The Systems Ba₂Nd_0.67(1?x)Y_0.67xWO₆ and Ba₂Nd_0.67W_1?xU_xO₆ In the system Ba₂Nd_0.67(1?x)Y_0.67xWO₆ the formation of a continuous series of mixed crystals with cubic 1:1 ordered perovskite structure is observed. The existence of a hexagonal modification is confined to the Y-rich side (x ≥ 0,9). In the Ba₂Nd_0.67W_1?xU_xO₆ series only for x ? 0,25 homogeneous cubic perovskites are obtained. In contrast to systems with other rare earths the Nd series show uncommon optical properties.     

Über die Eigenschaftsänderungen beim Einbau von Tav in Ba2Gd0,67UO6

The Variation of Properties by Incorporation of Ta^v in Ba₂Gd_0.67UO₆ In Ba₂Gd□_0.33U^VIO₆ the complete substitution of U^VI by Ta^V is only possible by filling up the gadolinium vacancies (Ba₂Gd_0.67+0.33xU_1?xTa_xO₆), whereas in the series Ba₂Gd_0.67U_1?yTa_yO_6–0.5y the phase boundary is reached with y = 0.1. Depending on x the variation of the properties is studied by X-ray and spectroscopic methods.     

Über hexagonale Perowskite mit Kationenfehlstellen. XXVII. Die Systeme Ba4−xSrxBIIRe2□O12′, Ba4BCaxRe2□O12 und Ba4−xLaxBIIRe2−xWx□O12 mit BII = Co,Ni

On Hexagonal Perovskites with Cationic Vacancies. XXVII. Systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄B Ca_xRe₂□O₁₂, and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ with B^II = Co, Ni In the systems Ba_4?xSr_xB^IIRe₂□O₁₂, Ba₄BCa_xRe₂□O₁₂ and Ba_4?xLa_xB^IIRe_2?xW_x□O₁₂ (B^II = Co, Ni) hexagonal perovskites with a rhombohedral 12 L structure (general composition A₄BM₂□O₁₂; sequence (hhcc)₃; space group R&3macr;m) are observed. With the exception of Ba₄NiRe₂□O₁₂ the octahedral net consists of BO₆ single octahedra and M₂□O₁₂ face connected blocks (type 1). In type 2 (Ba₄NiRe₂□O₁₂) the M ions are located in the single octahedra and in the center of the groups of three face connected octahedra. The two outer positions of the latter are occupied by B ions and vacancies in the ratio 1:1. The difference between type 1 and 2 are discussed by means of the vibrational and diffuse reflectance spectra.     

Über das System Ba2Sm0,67(1-x)La0,67xUO6

On the System Ba₂Sm_0.67(1?x)La_0.67xUO₆ In the Ba₂Sm_0.67xUO₆ system the boundary of the perovskite phase reachs up to x ? 0.33. With increasing Lanthanum content a transition from a structure with vacancies in the SE³⁺-sublattice to a lattice typ with interstitial oxygen is observed. By the interpretation of the reflectance and vibrational spectra the relations between colour and constitution are shown.     

Beiträge zur Chemie der Halogensilan-Addukte. XII. 1,10-Phenanthrolin-N-Oxid-Komplexe von Halogensilanen

On Perovskite Phases in the Systems AO? SE₂O₃? UO_2,x with A =Alkaline Earth Metal and SE = Rare Earths, La and Y. X. The Systems Ba₂CaUO₆? Ba₂CaUO₆? Ba₂Lu_0.67UO₆ and Ba₂SrUO₆? Ba₂Lu_0.67UO₆ In the systems Ba₂B_1?xLu_0,67x UO₆ with B^II = Ca, Sr at the B-rich side rhombic and at the Lu-rich side monoclinic perovskites are formed. The transition is discontinuous and accompanied by order-disorder phenomena.     

Über Das System Ba2Gd2/3□1/3U1−xWxO6 sowie hexagonale Perowskite vom 18-

On the System Ba₂Gd_2/3□_1/3U_1?xW_xO₆ and Hexagonal Perovskites of an 18-Layer Type In the system Ba₂Gd_2/3□_1/3U_1?xW_xO₆ the formation of a continuous solid solution series is observed. With x ? 0.9 the mixed crystals have a cubic 1:1 ordered perovskite structure. With x ≥ 0.95 the compounds are polymorphic: besides an cubic 1:1 ordered perovskite type for x = 0.95; 0.99 and 1.00 one hexagonal layer structure exists. This lattice is in all cases rhombohedral (space group R3 m) and represents an 18 L-type. Likewise the compounds Ba₂B□_1/3W^VIO₆ with B^III = Tb-Lu and Y belong to the 18 L-type.     

Crystal structures of disordered A2Mn3+M5+O6 (A=Sr,Ca; M=Sb,Nb, Ru) perovskites

Polycrystalline samples of A₂MnMO₆ (A=Sr, Ca; M=Nb, Sb, Ru) were prepared by conventional solid state synthesis and their crystal structures were determined using neutron powder diffraction data. All six compounds can be classified as distorted, disordered perovskites. The Mn³⁺/M⁵⁺ distribution is disordered in all six compounds. The strontium containing compounds, Sr₂MnMO₆ (M=Nb, Sb, Ru), undergo out of phase rotations of the octahedra about the c-axis (tilt system a⁰a⁰c⁻) leading to tetragonal I4/mcm space group symmetry. The calcium containing compounds, Ca₂MnMO₆ (M=Nb, Ru, Sb), have orthorhombic Pnma space group symmetry, as a result of a GdFeO₃-type octahedral tilting distortion (tilt system a⁻b⁺a⁻). A cooperative Jahn–Teller distortion is observed in Sr₂MnSbO₆ and Sr₂MnRuO₆, but it is much smaller than the distortion observed in LnMnO₃ (Ln=lanthanide ion) perovskites. It is possible that Jahn–Teller distortions of the MnO₆ octahedra take place on a short-range length scale in the other four compounds, but there is little or no evidence for cooperative ordering of the local distortions. These findings demonstrate a link between orbital ordering, cation ordering and octahedral tilting.     

Über Perowskitphasen in den Systemen BaO–SE2O3–UO2,x mit SE = Seltene Erden,La und Y. I. Verbindungen der Zusammensetzung Ba2SE0,67UO6 und Ba2SE0,67UO5,5

In the BaO–SE₂O₃–UO_2,x-system the formation of the polymorphic ordered perovskites Ba₂SE_0,67UO₆ ist observed. At the reduction of the former the ordered perovskites Ba₂SE_0,67UO_5,5 are formed, which contain U(V) only. According to the results of the magnetic and spectroscopic investigations the pentavalent uranium occupies the centers of slightly or strongly distorted octahedrons, while U(VI) is partly forming UO-groups. The rare earths are always present in the trivalent state. – The structural relations to the ordered perovskite A₂BB′O₆ are discussed.     

Über Perowskite Ba2BBTeVIO6

On Perovskites Ba₂B B Te^VIO₆ Compounds of composition Ba₂BBTe^VIO₆ with B^I = Li, Na; B^III = La, Pr, Nd, Sm, Eu, Gd, Tb, Ho, Yb, Y, In, Sc crystallize in a cubic 1:1 ordered perovskite structure. The vibrational spectroscopic investigations show, that more species of TeO₆ octahedra are present in the lattice.     

Ba6(MN4)N2–x (M = MoVI/TaV), a Subvalent Nitridometalate with Perovskite‐like Crystal Structure

The subvalent nitridometalate Ba₆[(Mo_1–xTa_x)N₄]N_0.86 was prepared from mixtures of Mo powder with Ba, Na, and Ba₂N at 600 °C in Ta ampoules. It crystallizes in space group Cmcm with a = 11.672(3), b = 10.177(2) and c = 10.8729(19) Å. Its crystal structure exhibits an orthorhombically distorted Perovskite topology with [Ba₆N] building units forming the ReO₃‐type lattice via common vertices, and the nitridometalate anions occupying half of the available distorted cuboctahedral interstices. [MN₄] anions show statistically mixed occupancy of M by Mo^VI and Ta^V. They show no notable deviation from nitridometalate anions in known ionic nitridomolybdates and ‐tantalates, and the metrics of the [Ba₆N] octahedra correspond to those found in similar subvalent compounds. The nitrogen atom position centering the [Ba₆N] octahedra is underoccupied. Band structure calculations corroborate the subvalent character of the compound and the two individual anionic structural building units.     

Über Das System Ba2Sm0,67U1−xWxO6

On the System Ba₂Sm _0.67U_1?xW_xO₆ The ordered perovskites Ba₂Sm_0.67UO₆ and Ba₂Sm_0.67 WO₆ are forming a complete serie of solid solutions with 4 formula units Ba₂Sm_0.67U_1?xW_xO₆ in the unit cell. By diffuse reflectance and i.r.-spectroscopic measurements the relations between color and constitution are shown.     

A Genuine Jahn–Teller System with Compressed Geometry and Quantum Effects Originating from Zero‐Point Motion

First‐principle calculations together with analysis of the experimental data found for 3d⁹ and 3d⁷ ions in cubic oxides proved that the center found in irradiated CaO:Ni²⁺ corresponds to Ni⁺ under a static Jahn–Teller effect displaying a compressed equilibrium geometry. It was also shown that the anomalous positive g_∥ shift (g_∥?g₀=0.065) measured at T=20 K obeys the superposition of the |3 z²?r²? and |x²?y²? states driven by quantum effects associated with the zero‐point motion, a mechanism first put forward by O'Brien for static Jahn–Teller systems and later extended by Ham to the dynamic Jahn–Teller case. To our knowledge, this is the first genuine Jahn–Teller system (i.e. in which exact degeneracy exists at the high‐symmetry configuration) exhibiting a compressed equilibrium geometry for which large quantum effects allow experimental observation of the effect predicted by O'Brien. Analysis of the calculated energy barriers for different Jahn–Teller systems allowed us to explain the origin of the compressed geometry observed for CaO:Ni⁺.     

Unexpected proline coordination in the copper chain polymer [Cu(μ‐Cl)2(μ‐DL‐proline‐κ2O:O′)]1∞

In catena‐poly[copper(II)‐di‐μ‐chlorido‐μ‐proline‐κ²O:O′], [CuCl₂(C₅H₉NO₂)]_n, two symmetry‐independent metal cations adopt distorted octahedral coordination, typical for d⁹ Jahn–Teller systems. Each chloride bridge is involved in both a short and a very long interaction with a Cu^II centre. The centrosymmetric crystal structure contains homochiral chains of opposite handedness which extend along the shortest lattice parameter (i.e. a). The O:O′‐bridging coordination mode of proline, although a common motif for such complexes in general, is remarkable for Cu^II; the vast majority of amino acid derivatives of this cation are characterized by N,O‐chelation.     

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.     

Über Neue Oxoruthenate vom Typ der 6 L-Perowskite: Ba3SrRu2−xTaxO9 (x = 0,8 und 1,4) mit einem Beitrag über Ba3CaRu2O9

On Novel Oxoruthenates of the 6 L-Perovskite Type: Ba₃SrRu_2?xTa_xO₉ (x = 0.8 and 1.4) with a Comment on Ba₃CaRu₂O₉ Single crystals of the phases Ba₃SrRu_2?xTa_xO₉ [(I): x = 0.8 and (II): x = 1.4] and the compound (III): Ba₃CaRu₂O₉ were prepared by a BaCl₂ flux and investigated by X-ray methods. (I)–(III) crystallizes with hexagonal symmetry space group P6 2c with lattice constants: (I) a = 6.003 Å; c = 15.227 Å; (II) a = 5.988 Å; c = 15.220 Å and (III) a = 5.891 Å; c = 14.571 Å. The crystal structures of these substances corresponds to the 6 layer perovskites with the stacking sequence (hcc)₂. All of them show a so far not described slightly distorted oxygen framework caused by the Sr²⁺ and Ca²⁺ ions.     

Über Perowskitphasen in den Systemen BaO–SE2O3–UO2,x mit SE = Seltene Erden,La und Y. II. Verbindungen der Zusammensetzung Ba2(SE0,67U0,33)UO6,17

In the BaO–SE₂O₃–UO_2.x system the formation of the compounds Ba₂(SE_0,67U_0.33)UO_6.17 is observed. They crystallize in a pseudocubic ordered perovskite lattice, and contain tetravalent and pentavalent uranium in the ratio 1:3. Their magnetic and spectroscopic properties are reported.     

Gibt es „Wolframylgruppierungen”︁? Über Perowskitphasen im System Ba2Y0,67UO6?Ba2CaWO6

Do ? Wolframyl Groups ”? Exist? On Perovskite Phases in the System Ba₂Y_0,67UO₆ ? Ba₂CaWO₆ In the system Ba₂Y_{0.67(1? x)}Ca_xU_{1? x}W_xO₆ a solid solution series is formed up to x ? 0.85. The properties are studied by x-ray and spectroscopic methods.     

A polymeric ladder complex: catena‐poly­[[[μ‐4,4′‐bipyridyl‐bis­[aqua(p‐amino­benzoato)copper(II)]]‐di‐μ‐4,4′‐bipyridyl] dinitrate tetrahydrate]

The title polymeric ladder complex, {[Cu₂(C₇H₆NO₂)₂(C₁₀H₈N₂)₃(H₂O)₂](NO₃)₂·4H₂O}_n, has been synthesized and spectroscopically characterized. The polymeric nature of the compound involves two non‐equivalent 4,4′‐bipyridyl ligands acting as almost orthogonal bridges joining the metal coordination Jahn–Teller‐distorted octahedra, and forming ladders packed under the influence of hydrogen bonds involving the uncoordinated amino group of the p‐amino­­benzoate ligand, the NO₃⁻ anion and the water mol­ecules.