Synthese und Kristallstruktur von Calcium-Kupfer-Diarsenat CaCuAs2O7

Synthesis and Crystal Structure of the Calcium Copper Diarsenate CaCuAs₂O₇ Solid state reactions led to single crystals of CaCuAs₂O₇. X-ray investigations revealed monoclinic symmetry, space group C⁵_2h-P2₁/c, lattice constants a = 7.272(1); b = 8.946(2); c = 9.307(2) Å; β = 109.48(2)°; Z = 4. CaCuAs₂O₇ is characterized by ¹_∞[CaO₆] chains, connected by As₂O₇ double tetrahedra and elongated square CuO₅ pyramids. The hitherto unknown crystal structure shows relationships to CaCuP₂O₇ but not to CaCuV₂O₇.     

Die Kristallstruktur von Kaliummonomethylcarbonat

Crystal Structure of Potassium Monomethylcarbonate Potassium monomethylcarbonate KCH₃CO₃ was obtained from reaction of dimethylcarbonate with potassium hydroxide in methanole. The crystal structure was determined (triclinic, P1 (no. 2), Z = 2, a = 380.9(2) pm, b = 558.9(3) pm, c = 985.3(3) pm, α = 100.71(2)°, β = 90.06(3)°, γ = 92.48(3)°, V = 205.9(2) · 10⁶ pm³, wR(F²) = 0.054, wR_obs(F) = 0.022). Structural relations between potassium monomethylcarbonate and potassium hydrogencarbonate are discussed.     

Die Kristallstruktur von KPdMIVF7 (MIV = Zr,Hf)

The Crystal Structure of KPdM^IVF₇ (M^IV = Zr, Hf) Blue single crystals of KPdZrF₇ are obtained by heating the binary fluorides in sealed Pt-tubes under dry argon (solid state reaction, T ≈? 720°C, t ≈? 14 d). The compound crystallizes orthorhombically in the space group Pnna-D (Nr. 52); lattice parameters are a = 1 132.3(5) pm, b = 797.5(2) pm, c = 639.8(1) pm; Z = 4 (Four cycle diffractometer data, AED2). According to [F₄PdF_2/1ZrF₅] distortet [PdF₆]-octaedra are connected with pentagonal-bipyramidal [ZrF₇]-polyhedra via two bridging F^?, resulting in [PdZrF₁₁]-groups. These [PdZrF₁₁]-groups built up a threedimensional-network with K⁺ in its spacings. KPdHfF₇ crystallizes isotypically (a = 1 136.1(3) pm, b = 796.4(2) pm und c = 638.8(1) pm; four cycle diffractometer data, AED2).     

Synthese und Kristallstruktur von Sr2Rh7P6

Synthesis and Crystal Structure of Sr₂Rh₇P₆ Single crystals of Sr₂Rh₇P₆ were obtained by reaction of the elements in molten lead at 1100 °C and investigated by X-ray methods. The compound crystallizes tetragonally (a = 11.080(2), c = 4.098(1) Å) and forms a crystal structure (P 4 2₁m; Z = 2) with ThCr₂Si₂ analogous units, which are linked with each other in a new way. Therefore the RhP₄ tetrahedra form bands of edge sharing chains parallel to [001] anstead of layers as in the ThCr₂Si₂ type structure. The arrangement enables a part of the P atoms to form short P–P distances of 2,26 Å and space for additional Rh atoms with a likewise distorted tetrahedral coordination of P atoms is obtained.     

Die Kristallstruktur von Na2NiAlF7—ein Beitrag zum Problem der wahren Raumgruppe orthorhombischer Weberite

The Crystal Structure of Na₂NiAlF₇ — a Contribution to the Problem of the True Space Group of Orthorhombic Weberites The X-ray single crystal structure determination of the orthorhombic weberite Na₂NiAlF₇ (a = 707.4(2), b = 1003.8(2), c = 731.5(1) pm; Z = 4) was performed in space group Imma, after all reflections hk0 with h(k) = 2n + 1 could be eliminated, as they proved simulated by Renninger effect and/or λ/2 reflections. The alternative space groups Imm2 resp. I2₁2₁2₁ of former weberite structure determinations thus became obsolete. The refinement using 880 independent reflections ended at wR = 0.0232. The resulting average distances within the framework of octahedra are Ni? F = 197.3, Al? F = 180.4 pm.     

Zur Kristallstruktur von SrZn(OH)4 · H2O

Crystal Structure of SrZn(OH)₄ · H₂O Colorless crystals of SrZn(OH)₄ · H₂O are obtained by electrochemical oxidation of Zn in a zinc/iron pair in an aqueous ammonia solution saturated with strontium hydroxide. The X-ray crystal structure determination was now successful including all hydrogen positions: P1 , Z = 2, a = 6.244(1) Å, b = 6.3000(8) Å, c = 7.701(1) Å, α = 90.59(1)°, β = 112.56(2)°, γ = 108.66(2)°, N(F ≥ 3σF) = 1967, N(Var.) = 84, R/R_w = 0.020/0.024. In SrZn(OH)₄ · H₂O Zn²⁺ is tetrahedrally coordinated by four OH^? -ions while Sr²⁺ has 6 OH^? and one H₂O as neighbours. The polyhedra around Sr²⁺ are connected to chains which are linked three-dimensionally by isolated tetrahedra [Zn(OH)₄]. Hydrogen bonds between H₂O as donor and OH^? are characterized by raman spectroscopy.     

Verfeinerung der Kristallstruktur von SrO2

Refinement of the Crystal Structure of SrO₂ Single crystals of SrO₂ have been obtained after high pressure/high temperature reaction of a SrO/KClO₃ mixture at 20 kbar, 1 400°C. The crystal structure was refined using 154 unique diffractometer data (I4/mmm; a = 3.5626(3), c = 6.6159(6) Å; Z = 2; R = 0.033, R_w = 0.022, S = 0.932). The O O distance (1.493(4) Å) is significantly longer than the one previously assumed. From a refinement of the site occupation factor for oxygen a composition SrO_1.95(2) has been found for the crystal investigated.     

Die Kristallstruktur von Ca2As2O7

The structure of Ca₂As₂O₇ (a ₀=7.05,b ₀=9.30,c ₀=4.89 Å; =101.3°; space groupC2/m-C _2h ³ ;Z=2) has been solved from 465 independent X-ray intensities collected on aWeissenberg-type diffractometer up to anR-factor of 2.4% for all intensities. The structure of Ca₂As₂O₇ represents a further Thortveitite structure type.

     

Die Kristallstruktur des Calciumazid-Dihydrates

Single crystals of Ca(N₃)₂·2 H₂O have been prepared from aqueous solutions at room temperature. The crystals are monoclinic,a=1 159.0 (3),b=614.2 (2),c=785.5 (2) pm, =106.52 (2)°,Z=4, space group P2₁/n. The crystal structure was determined by single crystal X-ray diffraction (1 109 Mo-K-reflexions,R=0.052). Calcium atoms are surrounded by four azide groups and four water molecules. The coordination polyhedra are antiprism which are sharing azide groups and water molecules to form layers. The lattice constants and powder pattern agree well with values reported earlier for Ca(N₃)₂ · 1.5 H₂O [1]. It was also shown, that Sr(N₃)₂ · 2 H₂O is isotypic with Ca(N₃)₂ · 2 H₂O.

     

Die Kristallstruktur von Fe12Zr2P7

Zusammenfassung Die Struktur einer ternären Phase im System Fe–Zr–P wurde mit Hilfe von Einkristallaufnahmen bestimmt und verfeinert. Die Kristallart entspricht der vonVogel undDobbener aufgefundenen Phase Fe₄ZrP₂ und hat eine Idealzusammensetzung von Fe₁₂Zr₂P₇. Die Gitterparameter der hexagonalen Kristallart sinda=9,0002 undc=3,5920 Å, die Raumgruppe ist . Die Struktur ist mit jener von Fe₂P verwandt.

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The crystal structure of a ternary phase in the system Fe–Zr–P has been determined and refined by means of singlecrystal X-ray methods. The phase, already described byVogel andDobbener as Fe₄ZrP₂, has the ideal composition Fe₁₂Zr₂P₇. The cell dimensions are found to be:a=9,0002 andc=3,5920 Å, the space group is . The crystal structure of Fe₁₂Zr₂P₇ is related to Fe₂P.

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Die Kristallstruktur von Ammonium-dioxodifluorovanadat

The Crystal Structure of NH₄VO₂F₂ Crystals of NH₄VO₂F₂ are monoclinic, space group Pc, a = 4.814(2), b = 11.434(3), c = 7.214(2) Å, β = 108.84(4)°. Z = 4. The VO₂F-ion is polymeric. The structure consists of endless chains of strongly distorted octahedra with common edges. Two adjacent polyhedra are linked by an asymmetrical oxygen bridge (bond lengths 1.74 and 2.21 Å) and an asymmetrical fluorine bridge (bond lengths 1.97 und 2.21 Å). The terminal V? O- and V? F-distances are 1.55 and 1.86 Å, respectively.     

Die Kristallstruktur von Thalliumtrifluorid

The crystal structure of thallium trifluoride The crystal structure of TlF₃ has been determined form single crystal diffraction data. The unit cell is orthorhombic, space group Pnma≠D, with a = 5.825, b = 7.024, c = 4.851 Å, Z = 4. Each Tl has 8 nearest F-neighbours. The Tl–F distances range from 2.09 to 2.49 Å.     

Die Kristallstruktur von MoAlB

Zusammenfassung MoAlB kristallisiert orthorhombisch mit den Zellabmessungena=3,212,b=13,985,c=3,102 Å. In der Raumgruppe Cmem-D _2h ¹⁷ besetzen alle drei Atomarten die Punktlage 4 c) mity _Mo=0,0891,y _Al=0,304,y _B=0,465.

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MoAlB crystallizes with an orthorhombic unit cell having the lattice constantsa=3.212,b=13.985,c=3.102 Å. The three kinds of atoms all occupy the position 4 c) of space group Cmcm-D _2h ¹⁷ withy _Mo=0.0891,y _Al=0.304,y _B=0.465.

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Die Kristallstruktur von Zirkoniumtetrachlorid

Zirconium(IV) chloride crystallizes in the monoclinic space group P2/c with a = 6.361, b = 7.407, c = 6.256 Å β = 109.30°, Z = 2. The single crystal X-ray structure analysis shows the structure to consist of an arrangement of [ZrCl_4/2Cl₂] zig-zag chains. Within the chains each Zr atom has an octahedral environment; the octahedra are linked through sharing edges, the two terminal Cl ligands being mutually in cis-position. The structure is closely related to those of TcCl₄, PtI₄ and MoOCl₃. The Zr? Cl bond lengths are 2.655 (bridge), 2.498 (bridge) and 2.307 Å (terminal) ZrBr₄, HfCl₄, and HfBr₄ are isostructural with ZrCl₄     

Kristallstruktur von BaGdCl5

Crystal Structure of BaGdCl₅ Colourless single crystals of BaGdCl₅ are obtained from a 1 : 2 molar mixture of BaCl₂ and GdCl₃. It crystallizes with the monoclinic space group C2/c with a = 552.1(2), b = 1925.7(5), c = 687.4(2) pm, β = 93.25(4)° in a new structure. Ba²⁺ and Gd³⁺ have coordination numbers of 8 + 2 and 8, respectively.     

Die Kristallstruktur von wasserfreiem Melaminiumchlorid

Crystal Structure of non‐aqueous Melaminium Chloride Melaminium chloride was obtained as colorless, needle‐shaped, single crystalline material from solid state reactions between melamin and ammonium chloride. The structure of [C₃N₆H₇]Cl was refined by single crystal X‐ray diffraction: I2/m, Z = 8, a = 852.87(4), b = 1704.4(1) c = 918.44(4) pm and β = 92.165(6)°. The crystal structure contains melaminium ions stacked to columns along [100] and linked via N‐H···N bridges to form bands along [001]. Both of the two distinct chloride ions are stabilized by six hydrogen bonds through distorted trigonal prismatic arrangements of hydrogen atoms to yield a supramolecular structure.