Synthese und Strukturaufklärung von SrBeLa2O5

A new compound of the formula SrBeLa₂O₅ was prepared by high temperature technique. Single crystal X-ray investigations led to orthorhombic symmetry (a=9.730,b=7.377,c=6.687 Å, space group: D _2h ¹⁶ -Pnma,Z=4). SrBeLa₂O₅ shows a typical tunnel structure of a three-dimensional connection of Sr, La/O-prisms, related to a distortedKgomé-network. The tunnels are occupied by La³⁺- and Be²⁺-ions. A detailed discussion of the polyhedra, their connection, and the statistical distribution of Sr²⁺ and La³⁺ within the trigonal O^2–-prisms are given.

     

Ein neuer Strukturtyp mit flächenverknüpften BaO6-Oktaedern: Ba6Nd2Al4O15

Summary A compound Ba₆Nd₂Al₄O₁₅ with a new structure-type was prepared by solid state reaction. It crystallizes with hexagonal symmetry, space group C _6v ⁴ – P 6₃mc;a=11.5696;c=6.9662 Å;z=2. Ba₆Nd₂Al₄O₁₅ has a dominating Ba/O-framework with incorporated AlO₆-octahedra and AlO₄-tetrahedra. A main feature of the structure are face connected BaO₆-octahedra. One of the point positions of the heavy atoms is occupied statistically by Ba²⁺ and Nd³⁺.

     

Über Oxocuprate,XXVI Synthese und Struktur eines Oxohalogenocuprat(I): Sr2CuO2Cl

Single crystals of Sr₂CuO₂Cl were prepared in a closed system of Ag- and quartz-tubes. The colorless crystals are extremly sensitive against moisture. X-ray investigation proves a trigonal symmetry (a=400.3;c-2767.9 pm, space group P3₁21-D ₃ ⁴ ). Sr²⁺ has a distorted octahedral coordination of 3 O^2– and 3 Cl^–. Cu⁺ shows a dumbbell like O^2– surrounding. The O-Cu-O bond angle (176.5°) differs from the usually value (180°).

     

A Thermodynamic Study Between 18-Crown-6 with Mg2+, Ca2+, Sr2+and Ba2+ Cations in Water–Methanol and Water–Ethanol Binary Mixtures Using The Conductometric Method

The complexation reactions between Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ cations with the macrocyclic ligand, 18-Crown-6 (l8C6) in water–methanol (MeOH) binary systems as well as the complexation reactions between Ca²⁺ and Sr²⁺ cations with 18C6 in water–ethanol (EtOH) binary mixtures have been studied at different temperatures using conductometric method. The conductance data show that the stoichiometry of all the complexes is 1:1. It was found that the stability of 18C6 complexes with Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺ cations is sensitive to solvent composition and in all cases, a non-linear behaviour was observed for the variation of log K _f of the complexes versus the composition of the mixed solvents. In some cases, the stability order is changed with changing the composition of the mixed solvents. The selectivity order of 18C6 for the metal cations in pure methanol is: Ba²⁺ > Sr²⁺ > Ca²⁺ > Mg²⁺. The values of thermodynamic parameters (Δ H _c ° and Δ S _c °) for formation of 18C6–Mg²⁺, 18C6–Ca²⁺, 18C6–Sr²⁺ and 18C6–Ba²⁺complexes were obtained from temperature dependence of the stability constants. The obtained results show that the values of (Δ H _c ° and Δ S _c °) for formation of these complexes are quite sensitive to the nature and composition of the mixed solvent, but they do not vary monotonically with the solvent composition.This revised version was published online in July 2005 with a corrected issue number.     

Das erste Erdalkalimetall-Argentato-Mercurat(II): BaAg2Hg2O4

Summary BaAg₂Hg₂O₄ was prepared by an oxygen high-pressure technique. Single crystal X-ray investigations led to tetragonal symmetry, space group D _4h ³ – P4/nbm;a=6.793;c=7.086 Å;Z=2. Hg²⁺ and Ag⁺ show dumb-bell like coordination by oxygen whereas Ba²⁺ ions are surrounded by 8 O^2– forming distorted cubes. The BaO₈-polyhedra distortions are discussed in respect to the incorporation of Hg²⁺ ions into the BaAg₂O ₄ ^2– network.

     

Zur Kristallchemie der tetragonalen Wolframbronze: Ba6FeNb9O30

Solid state reaction of BaCO₃, FeC₂O₄·2H₂O and Nb₂O₅ gave single crystals of Ba₆FeNb₉O₃₀. The crystal structure was solved by X-ray investigations (a=12.597,c=3.990Å, space group P 4 bm-C _4v ² ,Z=1). Ba₆FeNb₉O₃₀ crystallyzes in the tetragonal bronze type with a statistical distribution of Fe³⁺ and Nb⁵⁺ in the octahedral framework. The anisotropic temperature factors of barium are discussed with respect to the oxygen coordination.

     

Synthesis and crystal structure analysis of Sr8Cu3In4N5 and Sr0.53Ba0.47CuN

Single crystals of new quaternary compounds Sr₈Cu₃In₄N₅ and Sr_0.53Ba_0.47CuN were prepared, respectively, from a Sr–Cu–In–Na melt under 7 MPa of N₂ and from a Sr–Ba–Cu–In–Na melt under 0.5 MPa of N₂ by slow cooling from 1023 to 823 K. The crystal structures were determined by single-crystal X-ray diffraction. Sr₈Cu₃In₄N₅ has an orthorhombic structure (space group, Immm, Z=2, a=3.8161(5) Å, b=12.437(2) Å, c=18.902(2) Å), and is isostructural with Ba₈Cu₃In₄N₅. It contains nitridocuprates of isolated units ⁰[CuN₂] and one-dimensional linear chains _∝¹[CuN_2/2] and one-dimensional indium clusters _∝¹[In₂In_2/2]. Sr_0.53Ba_0.47CuN crystallizes in an orthorhombic cell, space group Pbcm, Z=4, a=5.4763(7) Å, b=9.2274(12) Å, c=9.0772(12) Å. The structure contains infinite zig-zag chains _∝¹[CuN_2/2] which kink at every second nitrogen atom.     

Synthese und Kristallstruktur von Sr3Ga2O5Cl2 und Sr3Fe1.18Al0.82O5Cl2

Solid state reactions, by using a flux, lead to the new compounds Sr₃Ga₂O₅Cl₂ (A) and Sr₃Fe_1.18Al_0.82O₅Cl₂ (B). By means of single crystal X-Ray determinations a monoclinic symmetry (space group C ₂ ² -P2₁, (A):a=9.569 (2) Å; (B):a=9.550 (2) Å,Z=4) was found. Both compounds are not isotypic to Sr₃Fe₂O₅Cl₂ but crystallize like Ba₃Fe₂O₅Cl₂.

     

Komplexe des vierwertigen Nickels mit o-Methylbenzamidoxim

Zusammenfassung Der Komplex des Ni²⁺ mit o-Methylbenzamidoxim (oMB), [Ni(oMB)₂], wurde mit H₂O₂ in Anwesenheit von Cu²⁺ oder unter Luftdurchblasen in alkalischer Lösung mit O₂ zu [Ni(oMB)₄] oxydiert. Die Ligandenzahl und die Bildungskonstante sindn=4 und lgK=7,33. Die Vierwertigkeit des Nickels wurde analytisch nachgewiesen. Die Oxydation verändert dasoMB nicht, wie aus dem IR-Spektrum ersichtlich ist. Die Geschwindigkeitskonstante istk=36,3 l/mol^–1 sec^–1 und entspricht einer bimolekularen Reaktion.

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Complexes of quadrivalent Ni with o-methylbenzamide oxime

The complex of Ni²⁺ with o-methylbenzamide oxime [Ni(oMB)₂] was oxidized to [Ni(oMB)₄] with H₂O₂ in the presence of Cu²⁺ or with O₂ by air-blowing in alkaline solution. The ligand number and the formation constant aren=4 and lgK=7.33, resp. It was proved analytically that nickel is 4-valent. The IR-spectra showed that the oxidation does not attackoMB. The speed constant isk=36.3 l/mole^–1 sec^–1, corresponding to a bimolecular reaction.

     

Über ein neues Oxoiridat(IV): Ba7Ir6O19

Summary The so far unknown compound Ba₇Ir₆O₁₉ was prepared by long time solid state reactions using a flux of BaCl₂. X-ray single crystal work lead to the space group C _2h ³ —C2/m;a=14.913;b=5.778;c=10.979 Å; =99.58°;Z=2. It crystallizes with a new structure type characterized by three face-shared octahedra. The Ir₃O₁₂-groups build up a threedimensional network with an incorporated Ba/O-frame.

     

Ein neues Oxoruthenat(IV): Ba4Ru1.1Mn1.9O10 mit statistischer Besetzung derM 4+-Metallpositionen

Summary (I) Ba₄Ru_1.1Mn_1.9O₁₀ was prepared and investigated by single crystal X-ray technique. It crystallizes with orthorhombic symmetry, space group C _2v ¹² -Cmc2_i,a=5.74;b=13.15;c=12.86 Å;Z=4. (I) showsM ₃O₁₂-groups of face connectedMO₆-octahedra. The octahedra are occupied in different manner by Ru⁴⁺ and Mn⁴⁺. It belongs to compounds withM ₃O₁₂-octahedra-tripel connected in isolated two-dimensional wave-like planes.

     

Strontium Tantalates with a Perovskite Structure: Their Conductivity and High-Temperature Interaction with Water

The interaction of perovskite-like solid solutions Sr_{6 – 2x} Ta_{2 + 2x} O_{11 + 3x} (x= 0–0.28) with water is studied, along with dependences of the solutions' conductivity on their composition and the atmosphere's temperature and humidity. The Sr_{6 – 2x} Ta_{2 + 2x} O_{11 + 3x} phases with high concentrations of structural oxygen vacancies are high-temperature mixed oxygen–hydrogen ionic conductors whose conduction is sensitive to the presence of water vapor up to 900°C. According to a thermogravimetric study, the amount of water incorporated into the complex-oxide matrix is proportional to the concentration of structural oxygen vacancies. The process of water incorporation is considered in terms of crystalline and chemical properties of the structure. The oxygen-deficient perovskites containing coordination-unsaturated metalatoms can reconstruct their coordination polyhedron by adding water molecules, with subsequent partial dissociation of water to hydroxyl groups. The proposed mechanism explains different states of water in the oxide and a two-stage nature of its removal: water molecules coordinating the metal atom and those surrounding OH^–leave the core in the first and second stages, respectively.     

Study of Complex Formation Between Dicyclohexano-18-Crown-6 (DCH18C6) with Mg 2+, Ca2+, Sr 2+, and Ba2+ Cations in Methanol–Water Binary Mixtures Using Conductometric Method

The complexation reactions between Mg²⁺,Ca²⁺,Sr²⁺ and Ba²⁺ metal cations with macrocyclic ligand, dicyclohexano-18-crown-6 (DCH18C6) were studied in methanol (MeOH)–water (H₂O) binary mixtures at different temperatures using conductometric method . In all cases, DCH18C6 forms 1:1 complexes with these metal cations. The values of stability constants of complexes which were obtained from conductometric data show that the stability of complexes is affected by the nature and composition of the mixed solvents. While the variation of stability constants of DCH18C6-Sr ²⁺ and DCH18C6-Ba²⁺versus the composition of MeOH–H₂O mixed solvents is monotonic, an anomalous behavior was observed for variations of stability constants of DCH18C6-Mg²⁺ and DCH18C6-Ca²⁺ versus the composition of the mixed solvents. The values of thermodynamic parameters (ΔH_c°, ΔS_c°) for complexation reactions were obtained from temperature dependence of formation constants of complexes using the van’t Hoff plots. The results show that in most cases, the complexation reactions are enthalpy stabilized but entropy destabilized and the values of thermodynamic parameters are influenced by the nature and composition of the mixed solvents. The obtained results show that the order of selectivity of DCH18C6 ligand for metal cations in different concentrations of methanol in MeOH–H₂O binary system is: Ba²⁺>Sr²⁺>Ca²⁺> Mg²⁺.     

Die Kristallstruktur von Ge5O[PO4]6

Zusammenfassung Die Kristallstruktur der Verbindung Ge₅O[PO₄]₆ wurde auf Grund dreidimensionaler Einkristalldaten ausWeissenberg-Aufnahmen ermittelt und nach der Methode der kleinsten Quadrate verfeinert: Raumgruppe ;a=7,994±0,004 undc=24,87±0,01 Å;Z=3; 467 unabhängige Reflexe;R=0,086.Die Kristallstruktur wird aus singulären [GeO₆]-Oktaedern und [Ge₂O₇]-Doppeltetraedern aufgebaut, die über [PO₄]-Tetraeder zu einem dreidimensionalen Strukturverband vernetzt sind. Die mittleren Abstände betragen: Ge^[6]–O=1,863, Ge^[4]–O=1,704 und P–O=1,525 Å.

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The crystal structure of Ge₅O[PO₄]₆

The crystal structure of Ge₅O[PO₄]₆ has been determined and refined by least-squares, using three-dimensional x-ray data fromWeissenberg-photographs: space group ;a=7.994±0.004 andc=24.87±0.01 Å;Z=3; 467 independent reflections;R=0.086.The crystal structure consists of isolated [GeO₆] octahedra and [Ge₂O₇] double tetrahedra which are linked by [PO₄] groups forming a three-dimensional network. The average interatomic distances are: Ge^[6]–O=1.863, Ge^[4]–O=1.704 and P–O=1.525 Å.

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Mit 2 Abbildungen     

Das Gleichgewicht zwischen oktaedrisch und tetraedrisch koordiniertem Kobalt(II) in N,N-Dimethylacetamid

Zusammenfassung In Lösung von [Co(DMA)₆](ClO₄)₂ in wasserfr. N,N-Dimethylacetamid (DMA) wird spektrophotometrisch ein Gleichgewicht zwischen tetraedrisch und oktaedrisch koordiniertem Co²⁺ festgestellt. Die GleichgewichtskonstanteK=[Co _tetr ²⁺ ]/[Co _oct ²⁺ ] wurde bei 25°C zu 0,028 und bei 70°C zu 0,19 bestimmt. Bei –8°C zeigen die Elektronenspektren keinen meßbaren Anteil der tetraedrischen Species. Für den oktaedrischen Komplex ergibt sichD _q =805 cm^–1,B=834 cm^–1.

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The equilibrium between octahedral and tetrahedral coordinated cobalt(II) in N,N-dimethylacetamide

Spectrophotometric results establish an equilibrium between tetrahedral and octahedral coordinated cobalt(II) in anhydrous N,N-dimethylacetamide (DMA). The equilibrium constantK=[Co _tetr ²⁺ ]/[Co _okt ²⁺ ] has been found to be 0,028 at 25°C and 0,19 at 70°C. Electronic spectra indicate no measurable amount of the tetrahedral species at –8°C. For the octahedral complexD _q =805 cm^–1 andB=834 cm^–1.

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Mit 4 Abbildungen     

Electronic absorption spectroscopy of alkaline earth metal uranate compounds

Summary Electronic absorption spectra have been measured by diffuse reflectance for MgUO_4–x, MgU₃O₉, CaUo)_4–x, Ca₂UO₅, Ca₃UO₆, Ca₂U₃O₁₁, CaU₂O₇, CaU₄O₁₂, SrUO₃, SrUO₄, SrUO_3.67, Sr₂U₃O₁₁, SrU₄O_12.8, Sr₂UO₅, Sr₃UO₆, BaUO₄, Ba₃UO₆, BaU₂O₇, Ba₂U₂O₇ and Ba₂U₃O₁₁.Measurements in the near i.r. region of the spectrum have identified transitions arising within the manifold of the 5f electronic levels which indicate the presence of uranium(V) in certain compounds. The portion of the spectrum between 20 000 and 30 000 cm^–1 is shown to contain charge-transfer transitions and, in certain instances, vibrational progressions which are characteristic of the symmetry of the UO₆ octahedron in the solid state structure.     

Synthese und Strukturuntersuchung von Zn3Ta2O8

Zn₃Ta₂O₈ was prepared by high temperature solid state reaction (CO₂-Lasertechnique). X-ray investigations of single crystals yield monoclinic symmetry (a=9.499;b=8.411;c=8.881 Å; =116.03°, space group C _2h ⁶ —C2/c). There is no relationship between Zn₃Ta₂O₈ and Zn₃Nb₂O₈. Zn₃Ta₂O₈ shows a characteristic structure type with octahedral coordination of Ta⁵⁺ and tetrahedral coordination of Zn²⁺.

     

Natural product chemistry,part 100: The structure of carissone,C15H24O2

Summary C₁₅H₂₄O₂,M=236.2, monoclinic, P 2₁,a=7.229(7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 ų,T=–133 °C,Z=2,D _x=1.17 g cm^–3. The X-ray diffraction analysis of this sesquiterpenoid fromCarissa opaca confirmed the previously proposed constitution of the isolate and, furthermore, allowed precise NMR assignment.

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Naturstoffchemie, 100. Mitt.: Die Struktur des Carissons, C₁₅H₂₄O₂

Zusammenfassung C₁₅H₂₄O₂,M=236.2, monoklin, P 2₁,a=7.229 (7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 ų,T=–133 °C,Z=2,D _x=1.17 g cm^–3. Die Röntgenstrukturanalyse dieses Sesquiterpenoids ausCarissa opaca bestätigte die bereits vorgeschlagene Struktur und erlaubte ferner eine genaue NMR-Zuordnung.

     

Structural, Infrared, and Magnetic Characterization of the Solid Solution Series Sr2−xPbx(VO)(VO4)2; Evidence of the Pb6sLone Pair Stereochemical Effect

The solid solution Sr_2−xPb_xV₃O₉, 0≤x≤2, was prepared by solid state reactions and characterized by X-ray diffraction, IR spectroscopy, and magnetic susceptibility measurements. Single crystals of the pure strontium phase and mixed Sr/Pb compounds were prepared by high temperature treatment of the respective powder compositions. Pb₂V₃O₉crystals could only be obtained by the electrochemical reduction of molten PbV₂O₆. These crystals were always twinned. The previously reported crystal structure of Sr₂V₃O₉was confirmed. It was refined toR=0.050,R_w=0.057, in space group C2/c,a=7.555(1) Å,b=16.275(2) Å,c=6.948(1) Å,β=119.78(1)°. The single crystal structural studies of the Sr_1.02Pb_0.98V₃O₉and Sr_0.67Pb_1.33V₃O₉members of the series show that the introduction of lead gives rise to a progressively complicated splitting of Sr²⁺/Pb²⁺and the tetrahedral vanadium ion crystallographic sites. As a consequence the vanadium framework distorts and beyond the Sr_0.5Pb_1.5V₃O₉composition the crystal symmetry becomes triclinic. This distortion is ascribed to the stereochemical effect of the 6s²lone pair of Pb²⁺. The crystallographic parameters of Pb₂V₃O₉area=7.598(1) Å,b=16.393(3) Å,c=6.972(2) Å,α=91.38(1)°,β=119.35(1)°,γ=90.47(1)°. Pb₂V₃O₉exhibits a more complex IR spectrum than the monoclinic phases. Despite the similarity between the triclinic and monoclinic phases the magnetic susceptibilities indicate differences in the coupling between V⁴⁺ions at low temperatures.     

Über Erdalkalimetalloxogallate. VIII Synthese und Aufbau eines neuen Calciumoxogallats: Ca3Ga4O9

The hitherto unknown compound Ca₃Ga₄O₉ was prepared and investigated by X-ray single crystal methods. Ca₃Ga₄O₉ has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C _2v ¹¹ –Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO₄-tetrahedra) and the surrounding of Ca²⁺ are described and discussed with respect to other oxogallates.