Disorder in the crystal structure of NaNi4(PO4)3

NaNi₄(PO₄)₃ crystallizes in the space group Amam, a = 9.892(1), B = 14.842(2), and c = 6.3576(2) Å. For Z = 4, the calculated density is 3.862 g/cm³ (V = 933.3ų). The presence of several weak reflections (of the class 2k0 and 6k0) which should be systematically absent in this space group has been attributed to a partial disorder of one of the phosphate tetrahedra. Two half-occupied P(2) sites related by a mirror normal to the a axis result in a column of phosphate tetrahedra pointing either up or down in this direction. Nickel atoms occupy five- and six-coordinated sites while sodium is six-coordinated.     

Synthesis and crystal chemistry of NH3(MoO3)3

NH₃(MoO₃)₃ crystallizes with hexagonal symmetry, space group $\text{P6}{}_3\text{m}$, lattice constants a = 10.568 Å, c = 3.726 Å, and Z = 2. The crystal structure has been determined by Patterson synthesis and refined assuming isotropic temperature factors to a final conventional R value of 0.085. The structure shows a three-dimensional arrangement built up of double chains of distorted MoO₆ octahedra, parallel to the [001] direction. The octahedral double chains are linked among each other through common oxygen atoms. In addition to the shared oxygen atoms, each molybdenum is coordinated to one terminal oxygen. MoO distances range from 1.645 to 2.378 Å and OMoO angles from 74.3 to 114.3°. These results are consistent with the fact that molybdenum in high-valence states shows octahedral coordination with terminal oxygens.     

Intercalation phases of TiS2, 2HNbS2, and 1TTaS2 with ethylenediamine and trimethylenediamine: A crystal chemical and thermogravimetric study

The title compounds were prepared and chemicaly analyzed. Their crystal structures were determined from rotating crystal photographs. 1T-, 2H-, and two different 3R-polymorphs were observed. The thermogravimetric analysis, revealing two to four distinct steps for the phases derived from TiS₂ and 2HNbS₂, and only one to two smeared-out steps for those derived from 1TTaS₂, proves the coexistence of strongly and weakly bound intercalate molecules. The first ones cannot be thermally deintercalated without chemical decomposition. The results are discussed within the framework of an ionic bonding model.     

VOCl3: Crystallization,crystal structure,and structural relationships: A joint X-ray and 35Cl-NQR investigation

Cooling of VOCl₃ below its melting point (196 K) yields an amorphous phase, which transforms into the crystalline state upon further cooling. The crystallization is accompanied by a remarkable change in color from pale yellow to deep orange. A single crystal has been grown from the amorphous phase. VOCl₃ crystallizes in the orthorhombic system, space group Pnma, with lattice parameters a = 4.963(1), b = 9.140(4), c = 11.221(5)Å at 133 K; Z = 4. The ³⁵Cl-NQR experiments show two signals at approximately 11.4 MHz of intensity 2:1, which implies two different crystallographic sites for chlorine atoms, in agreement with the centrosymmetric space group Pnma. The crystal structure exhibits isolated tetrahedral molecules VOCl₃ lying on a mirror plane and stacked with their VO axis along [100] to form trigonal prismatic columns. A close relationship exists with the structure of AsBr₃, in which the lone pair occupies the position corresponding to the oxygen atoms.     

Single-crystal growth and crystal structure refinement of CuAlO2

Single crystals of the delafossite-type compound CuAlO₂ were grown from Al₂O₃Cu₂O melt by a slow-cooling method from 1200°C. Three types were found in as-grown crystals (single crystals, short-columnar twin crystals with concave angles, and laminar twin crystals). The twinning form is similar to the spinel-type twin. CuAlO₂ is rhombohedral, $\text{R}\text{3}\text{m, a = 2.8604(7), c = 16.953(5)}\text{A}\text{?}$, Z = 3, Dx = 5.12 g/cm³ and Dm = 5.06 g/cm³. The crystal structure of CuAlO₂ was analyzed by means of single-crystal X-ray diffraction with a conventional R value = 0.038. The value of the U₁₁ component of the thermal parameter of Cu⁺ was twice as large as U₃₃.     

Thermal decomposition of organo-bielemental vanadium compounds Cp2V(ER3) (ER3 - GeEt3, SnEt3, CH2SiMe3 SeGeEt3)

The thermal decompositon of a number of organo-bielemental vanadium compounds with the general formula Cp₂V(ER₃) (ER₃ - GeEt₃, SnEt₃, CH₂SiMe₃, SeGeEt₃) has been investigated in solids and in solution. The main decomposition products of Cp₂V(SnEt₃) are vanadocene and hexaethyldistannane. Et₃GeH, Et₃GeCp, Cp₂V and CpV(C₅H₄GeEt₃) are formed from Cp₂V (GeET₃) decomposition. Isolated CpV(C₅H₄GeEt₃) is characterized by IR and mass spectra. The decomposition of Cp₂V(CH₂SiMe₃) is accompanied by Me₄Si, Cp₂V and CpV-(C₅H₄CH₂SiMe₃) formation, the latter is identified from the mass spectrum. Triethylgermane, vanadocene, and a diselenide of vanadium are isolated on decomposition of Cp₂V(SeGeEt₃). Based upon the experimental data, mechanisms for the decompositon are proposed.     

Sm2O3Ga2O3 and Gd2O3Ga2O3 phase diagrams

Four definite compounds exist in the Sm₂O₃Ga₂O₃ binary phase diagram, namely: Sm₃GaO₆, Sm₄Ga₂O₉, SmGaO₃, and Sm₃Ga₅O₁₂. The $\text{3}\text{1}$ compound is orthorhombic (space group Pnna - Z.4) with the cell parameters: a = 11.40₀Å, b = 5.51₅Å, c = 9.07Å and belongs to the oxysel family. Sm₃GaO₆ and SmGaO₃ melt incongruently at 1715 and 1565°C; Sm₄Ga₂O₉ and Sm₃Ga₅O₁₂ have a congruent melting point at 1710 and 1655°C. With regard to the Gd₂O₃Ga₂O₃ system three definite compounds have been identified: Gd₃GaO₆, Gd₄Ga₂O₉, and Gd₃Ga₅O₁₂. Only the garnet melts congruently at 1740°C with the following composition: Gd_3.12Ga_4.88O₁₂. Gd₃GaO₆, and Gd₄Ga₂O₉ melt incongruently at 1760 and 1700°C. GdGaO₃ is only obtained by melt overheating which may yield an equilibrium or a metastable phase diagram.     

The crystal structure of Cu4(PO4)2O

Cu₄(PO₄)₂O crystallizes in the space group $\text{P}\text{1}$ with a = 7.5393(8) Å, b = 8.1021(9) Å, c = 6.2764(8) Å, α = 113.65(1)°, β = 98.42(1)° and γ = 74.19(1)°. The structure was refined by full-matrix least-squares techniques using automatic diffractometer data to R = 0.046 (R_w = 0.056). Four unique copper atoms are in six, five-, and four-coordinated polyhedra which are linked together to form a three-dimensional network. The structure is best described in terms of a cubic close-packed array of oxygen atoms with one-tenth of the possible anion sites vacant.     

The structure of a cubic hydrogen rhenium bronze,H1.36ReO3

The structure of D_1.36ReO₃ has been determined by a room temperature powder neutron diffraction study. The unit cell is body centered cubic (space group Im3) and contains eight formula weights (a = 7.497 ± 0.001Å). A least squares method based on peak intensities was used to refine the structure. The rhenium atoms lie on the special perovskite sites and are surrounded by distorted octahedra of oxygen atoms which are displaced towards the vacant perovskite A sites. The deuterium atoms are statistically distributed over 72 possible sites in the unit cell, as OD bonds.     

The crystal structure of hydrogen cerium(III) sulfate hydrate, [H3O][Ce(SO4)2] · H2O

[H₃O][Ce(SO₄)₂] · H₂O crystallizes in the monoclinic system with unit-cell dimensions (from single-crystal data) a = 9.359(4), b = 9.926(4), c = 8.444(3) Å, β = 96.53(9)° and space group P2₁/n, z = 4. The structure was solved by conventional heavy-atom methods using 1787 counter-measured reflections (MoKα radiation), and refined using full-matrix least-squares techniques to an R of 0.0465 (ωR = 0.0413). The structure consists of cerium(III) ions in irregular nine-coordination to oxygen atoms from two bidentate sulfate ions, four monodentate sulfate oxygen atoms, and one water molecule. The oxonium ions are present as isolated ions in the structure and take par in the hydrogen bonding network. The Ce-O bond lengths range from 2.454(7) to 2.626(6) Å.     

Proton motion in HNbO3 and HTaO3

Proton NMR relaxation times T₁, T_1?, and T₂ are reported for the compounds HTaO₃ and HNbO₃ in the temperature range 170–540 K. The data show that for both compounds two types of motion occur. Proton diffusion occurs in both compounds above 400 K with a correlation time, τ⁰_c, of ～30 ps and an activation energy of ～50 kJ mole^?1, approximately twice that for the localized process occurring at lower temperatures. Alternating current conductivity measurements have been used to study proton diffusion above 470 K in these compounds.     

A complex with a bridging thiocarboxamido group: the crystal structure of Fe4(CO)12S(CSNMe2)(CNMe2)

The structure of the compound Fe₄(CO)₁₂S(CSNMe₂)(CNMe₂) has been determined by X-ray crystallography. The compound crystallizes in space group P2₁/c with four molecules in a unit cell of dimensions a 8.840(2), b 20.174(9), c 16.856(5)Å, β 114.82(3)°. Full-matrix least-squares refinement of 2881 counter data yielded R = 0.046. The molecule consists of two Fe₂(CO)₆ units bridged by thiocarboxamido and immoniocarbene ligands and by a common bridging sulfur atom. The structure of this compound is compared with those of related molecules and a detailed comparison is made of the bonding properties of the thiocarboxamido ligand in bridging and chelating configurations.     

Ambient pressure synthesis,properties, and structure refinements of VP4 and CoP2

The previously reported compounds VP₄ and CoP₂, prepared at high pressure, were synthesized in well-crystallized form at ambient pressure by reaction of the elemental components in the presence of iodine. Their structures were refined from single-crystal X-ray diffractometer data to conventional residuals of R = 0.033 for VP₄ (CrP₄ type structure, 11 variables, 815 F values) and R = 0.019 for CoP₂ (arsenopyrite structure, 14 variables, 932 F values). VP₄ is paramagnetic and a metallic conductor. CoP₂ is a diamagnetic semiconductor with an activation energy of 0.34 eV. Chemical bonding and potential displacive phase transitions of these compounds are discussed.     

Normal modes of the MoO2−4 ion in Tb1.8Eu0.2(MoO4)3 single crystal

Polarized Raman spectra (single crystal) at 300 K and infrared spectra (powder) at 300 and 77 K in the region 250–1000 cm^?1 of a binary molybdate of terbium and europium have been recorded. Based on C_2v symmetry, group theoretical analysis has been carried out and a vibrational assignment is proposed.     

Infrared spectra of Ag2BrNO3 and Ag2ClNO3

The infrared spectra of Ag₂BrNO₃ and Ag₂ClNO₃ are reported. Vibration assignments are proposed on the basis of the group theoretical analysis and D_2h symmetry. Factor group, site and TO-LO splittings are observed. The internal and external mode frequencies are correlated with those of AgNO₃ and KNO₃(II).     

Transition metal complexes with long-chain amines thermal behaviour and crystal structure of (n-CaH2a+1NH2)2ZnCl2

The thermal behaviour of (n-C_aH_2n+1NH₂)₂ZnCl₂ complexes with n = 6, 8, … 16 has been investigated by DSC and by temperature variable IR and X-ray powder diffraction techniques. Complexes with n = 12,14,16 show solid—solid phase transition which are “melting” transitions of the hydrocarbon regions of the structure. The crystal structure of both the low and the high temperature polymorphs is characterized by the piling of sandwiches, each formed by an “inorganic” layer sandwiched between two alkylammonium layers.     

The crystal and magnetic structures of Sr2YRuO6

Time-of-flight powder neutron diffraction data have been used to refine the crystal structure of the ordered, distorted perovskite Sr₂YRuO₆. Yttrium and ruthenium are octahedrally coordinated in this material with average MO bond lengths of 2.202 and 1.955 Å, respectively. Constant wavelength neutron diffraction data show that Sr₂YRuO₆ is a Type I antiferromagnet at 4.2 K with an ordered magnetic moment of 1.85 μ_B per Ru⁵⁺ ion. The Néel temperature of Sr₂YRuO₆ was determined to be 26 K. The data suggest that the 4d³ electrons in this material are localized rather than itinerant.     

Three-coordinate RhX[P(C6H11)3]2, their reactions with N2 and O2, and the trans-influence in RhX[P(C6H11)3]2L (X = anionic,L = neutral ligand)

Three-coordinate RhX(PCy₃)₂ complexes (X = F, Cl, Br, I; Cy = cyclohexyl) have been prepared from rhodium(I) cyclooctene compounds. RhCl(PCy₃)₂ is in equilibrium with its dimer. The complexes RhX(PCy₃)₂ (X = Cl, Br, I) form the adducts RhX(PCy₃)₂(N₂) with dinitrogen, the times for N₂-fixation being 4 days, 3 hours and 15 minutes respectively. The three-coordinate complexes form four-coordinate dioxygen adducts RhX(PCy₃)₂(O₂) which have unusually high ν(OO) at about 990 cm^?1. This high frequency is attributed to the four-coordination, which is exceptional for dioxygen complexes. From RhF(PCy₃)₂ carbonyl, ethene, and diphenylacetylene complexes RhX(PCy₃)₂L (X = F, Cl, Br, I, N₃, NCO, NCS; L = CO, C₂H₄, C₂Ph₂) (X = CN, NO₃, acetate; L = CO) have been prepared. The trans-influence of the anionic ligands on the infrared frequencies of the neutral ligands is discussed in terms of the different π-bonding properties of the X- and L-ligands.     

The system BaOGeO2 at high pressures and temperatures,with special reference to high-pressure transformations in BaGeO3, BaGe2O5, and Ba2Ge5O12

Phase relations in the system BaOGeO₂ were investigated in the pressure range 20–70 kbar in the temperature range 750–1200°C. Several new phases were identified in this system: an atmospheric phase of BaGe₂O₅ (monoclinic BaGe₂O₅ I), two high-pressure phases of BaGe₂O₅ (monoclinic BaGe₂O₅ II and tetragonal BaGe₂O₅ III), and a high-pressure phase of Ba₂Ge₅O₁₂. The phase boundary curve between BaGe₂O₅ II and BaGe₂O₅ III was preliminarily determined as P(kbar) = 7.7 + 0.047T (°C). The high-pressure phases of BaGeO₃, which were previously reported by Y. Shimizu, Y. Syono, and S. Akimoto (High Temp.-High Pressures2, 113 (1970)) in the pressure range 15–95 kbar, were interpreted to be not single-phase materials but complicated mixtures of more than two phases in the system BaOGeO₂. X-Ray powder diffraction data for the new compounds synthesized in this study are given.     

Darstellung und chemie von Me2TlN(SiMe3)2 und Tl[N(SiMe3)2]3

The complexes [Rh(η³-C₃H₄R)(η⁵-C₅R′₅)L]⁺BF₄^- (R  1-Me, R′  H, Me; R  2-Me, R′  H) (L  C₅H₅N, Ph₃P, Ph₃As) have been prepared from Rh(η³-C₃H₄R)(η⁵-C₅R′₅)Cl and AGBF₄ in acetone, followed by reaction with the stoicheiometric quantity of L. The ¹H and ¹³C NMR spectra of the salts are reported and discussed.