Synthesis of non-equilibrium PtxOs1−x Solid solutions. Crystal structure of [Pt(NH3)4][OsCl6]

Several non-equilibrium solid solutions belonging to the platinum-osmium systems Os_0.9Pt_0.1, Os_0.8Pt_0.2, Os_0.5Pt_0.5, Os_0.7Pt_0.3, Os_0.75Pt_0.25 are prepared and studied. The thermal decomposition of [Pt(NH₃)₄][OsCl₆] in the hydrogen and helium atmosphere is investigated. It is found that the Pt_0.5Os_0.5 solid solution develops through the formation of (NH₄)₂[OsCl₆] and a metallic phase based on Pt. The crystal structure of a double complex salt [Pt(NH₃)₄][OsCl₆] is studied (X8-APEX Bruker, 1508 independent reflections, R = 2.04%). Crystal data for PtOsN₄Cl₆H₁₂ are: a = 11.6216(5) Å, b = 11.0016(5) Å, c = 10.3819(5) Å, V = 1327.4(1) ų, space group Cmca, Z = 4, d _x = 3.333 g/cm₃. The coordination polyhedron around Os is octahedral: 〈Os-Cl〉 2.357 Å, ∠Cl-Os-Cl 89.5–90.5°, while around Pt it is square-planar: Pt-N 2.046 Å, ∠ N-Pt-N 89.59° and 90.41°.     

X-ray diffraction study of benzothiacrown compounds and their complexes with heavy metal cations

The structures of a series of substituted benzothiacrown compounds containing the dithia-15-crown-5, dithia-18-crown-6, or monothia-15-crown-5 fragment and their complexes with Ag⁺ and Pb2⁺ ions were studied by X-ray diffraction. In free benzothiacrown compounds, the sulfur atoms are preferably located outside the macrocyclic cavity, and their lone electron pairs (LEPs) point away from the center of the macrocycle, which is unfavorable for the formation of inclusion complexes. Flexible macrocyclic fragments can change their conformations in accord with the coordination requirements of heavy metal cations. As a result, benzothiacrown compounds involved in complexes adopt a crown conformation, in which LEPs of all hetero-atoms point toward the cation. The sulfur atoms are involved in coordination of Ag⁺ to a greater degree than the oxygen atoms due to high affinity of soft sulfur atoms for silver cations. On the contrary, the sulfur and oxygen atoms are involved to approximately the same degree in coordination of Pb2⁺ ions. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 967–976, May, 2007.     

Synthesis,structure, and properties of the thermolysis products of [Os(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl][ReCl<Subscript>6</Subscript>]

The crystal structure of [Os(NH₃)₅Cl][ReCl₆] has been refined by X-ray powder analysis: a = 11.645(3) Å, b = 8.3788(2) Å, c = 15.277(4) Å, β = 91.029(6)°, V = 1490(1) ų, d _x = 3.163 g/cm³, space group P2₁/m, Z = 4. The thermolysis product of the salt in a hydrogen atmosphere is a solid substitution solution Os_0.5Re_0.5: a = 2.753(2) Å, c = 4.366(3) Å, space group P6₃/mmc; coherent scattering region (CSR) is ～230 Å.     

X-ray and neutron powder diffraction study of the double perovskites Ba2LnSbO6 (Ln=La, Pr, Nd and Sm)

The crystal structures of Ba₂LnSbO₆ (Ln=La, Pr, Nd and Sm) at room temperature have been investigated by profile analysis of the Rietveld method using either combined X-ray and neutron powder diffraction data or X-ray powder diffraction data. It has been shown that the structure of Ba₂LnSbO₆ with Ln =La, Pr and Nd are neither monoclinic nor cubic as were previously reported. They are rhombohedral with the space group . The distortion from cubic symmetry is due to the rotation of the LnO₆/SbO₆ octahedra about the primitive cubic [111]_p-axis. On the other hand, the structure of Ba₂SmSbO₆ is found to be cubic. All compounds contain an ordered arrangement of LnO₆ and SbO₆ octahedra.     

Complexation of (carbamoylmethyl)diphenylphosphine sulfide with silver nitrate. The structure of the polymeric complex [Ag2{Ph2P(S)CH2C(O)NH2}2(NO3)2] n

The reaction of (carbamoylmethyl)diphenylphosphine sulfide with AgNO₃ yields the polymeric complex [Ag₂{Ph₂P(S)CH₂C(O)NH₂}₂(NO₃)₂] _n . Its structure was established by X-ray diffraction analysis. The coordination environments about both Ag⁺ cations are formed by five donor atoms, two of which are bonded to the metal atom substantially more weakly than the remaining three atoms. The compositions of the coordination polyhedra are different: ({AgSO′(C)O(N)O₂(N′)} and {AgS′ SO(C)O₂(N)}). The coordinated ligands differ in their functions: one ligand chelates the metal cation and its sulfur atom is additionally bonded to the second cation, while the second ligand acts as a bridge between the two different cations. The structure of the complex and the character of the interaction between the ligand and AgNO₃ are substantially affected by the network of hydrogen bonds. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 838–845, April, 1997.     

The crystal structure of 3-methyluracil from X-ray powder diffraction data

The crystal structure of 3-methyluracil has been determined ab initio by conventional monochromatic X-ray powder diffraction data. The crystal data are: orthorombic, a=6.6294(1), b=13.1816(3), c=6.53938(9) (Å), V=571.45(3) (ų), space group Pbnm, Z=8. The structure was solved by direct methods and the final Rietveld refinement converged to R_p=0.0398, R_wp=0.0528, R_Bragg=0.0294. The crystal structure exhibits endless chains of planar molecules, connected via head-to-tail N-H?O hydrogen bonds.     

Complexation of (N, N-diethylthiocarbamoylmethyl) diphenylphosphine sulfide with silver nitrate. The structure of the [Ag{Ph2P(S)CH2C(S)NEt2}2]NO3 complex

(N, N-Diethylthiocarbamoylmethyl)diphenylphosphine sulfide, Ph₂P(S)CH₂C(S)NEt₂, forms a distorted tetragonal bisligand complex [AgL₂]NO₃ with Ag⁺. The stability constant of the complex in acetonitrile was estimated by spectrophotometry (logK=3.7). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 846–852, April, 1997.     

Quantification of flupirtine maleate polymorphs using X-ray powder diffraction

Flupirtine maleate,a pharmaceutical compound for treating psychotic disease in clinics,has seven polymorphs.Form A,with better crystal stability and bioavailability,has been widely used as the pharmaceutical crystal form.Unfortunately,it is usually found in a polymorphic mixture with form B.In this study,pure crystal forms of A and B were prepared and characterized by X-ray powder diffraction (XRPD),Fourier transform infrared spectroscopy (FT-IR) and thermal analysis.An XRPD-based method for the quantitative determination of the amount of the flupirtine maleate polymorphs form A and form B was also established through a systematic optimization of instrumental parameters.The results of the analytical methodology validation showed that the XPRD method had a broad quantitative range of 0-100%(w/w),good linear relationship,with R²=0.999,excellent repeatability and precision and low limits of detection (LoD) of 0.15%(w/w) and quantification (LoQ) of 0.5%(w/w).The results also showed that the single-peak method was not as good as the whole pattern in reducing the influence of the preferred orientation,but this can be compensated for by a systematic optimization of instrumental parameters and validating the analytical methodology to reduce errors and obtain a good,repeatable,sensitive,and accurate method.This XRPD method can be used to analyze mixtures of flupirtine maleate polymorphs (forms A and B) quantitatively and control the quality of the bulk drug.     

Structures and crystal chemistry of the double perovskites Ba2LnB′O6 (Ln=lanthanide B′=Nb and Ta): Part I. Investigation of Ba2LnTaO6 using synchrotron X-ray and neutron powder diffraction

The structure of 14 compounds in the series Ba₂LnTaO₆ have been examined using synchrotron X-ray diffraction and found to undergo a sequence of phase transitions from I2/m monoclinic to I4/m tetragonal to cubic symmetry with decreasing ionic radii of the lanthanides. Ba₂LaTaO₆ is an exception to this with variable temperature neutron diffraction being used to establish that the full series of phases adopted over the range of 15-500 K is P2₁/n monoclinic to I2/m monoclinic to rhombohedral. The chemical environments of these compounds have also been investigated and the overbonding to the lanthanide cations is due to the unusually large size for the B-site in these perovskites.     

Chiolite-like Ca5Te3O14: An X-ray and neutron diffraction study

The crystal structure of Ca₅Te₃O₁₄ at room temperature was studied by the Rietveld method using combined X-ray and neutron powder diffraction data. The compound crystallizes in the space group Cmca with the lattice parameters a=10.4268(2) Å, b=10.3908(2) Å and c=10.4702(2) Å. The structure of Ca₅Te₃O₁₄ is chiolite-like and consists of a framework of corner-linked TeO₆ octahedral layers in which a linear TeO₂ group of every fourth octahedron is substituted by a Ca atom. This type of structure was previously observed in BaSr₄U₃O₁₄. The relationship between the chiolite-like structure and the fluorite structure is discussed.     

Analysis of urinary stone constituents using powder X-ray diffraction and FT-IR

Constituents of urinary stones obtained from various patients from western part of India, which is a highly urinary stone disease-prone area, have been analysed. Eight stones from four patients were collected through urologists and have been analysed using powder X-ray diffraction and FT-IR. Thermogravimetric analysis (TGA) and scanning electron microscopic (SEM) image of selected samples were also carried out. The analysis revealed that calcium oxalate monohydrate, which is also known as whewellite, is the common constituent of all of the stones, particularly at the initial stage of stone formation. However, multi phases viz. whewellite phase, and hydroxyl and carbonate apatite phases are also detected in the case of third and fourth patients, from where multiple stones were obtained. Interestingly, in these mixed phase stones the concentration of whewellite decreases with increasing the concentration of apatite phases. Thermal behaviour of the whewellite phase was studied by TGA and variable temperature XRD analysis. Morphology of the whewellite and apatite phases, examined by SEM image, has also been reported.     

The structure of CeAlO3 by Rietveld refinement of X-ray powder diffraction data

The room temperature structure of perovskite CeAlO₃ has been reinvestigated by X-ray powder diffraction. The Rietveld refinement has confirmed the tetragonal symmetry; but revealed a super cell, a=5.32489(6) Å and c=7.58976(10) Å, with the space group I4/mcm. In CeAlO₃, the distortion from the ideal cubic perovskite is caused by the cooperative tilting of the AlO₆ octahedra around the primitive cubic [001]_p-axis.     

Ab initio structure determination via powder X-ray diffraction

Structure determination by powder X-ray diffraction data has gone through a recent surge since it has become important to get to the structural information of materials which do not yield good quality single crystals. Although the method of structure completion when once the starting model is provided is facile through the Rietveld refinement technique, the structure solutionab initio is still not push-button technology. In this article a survey of the recent development in this area is provided with an illustration of the structure determination of α-NaBi₃V₂O₁₀.     

DTA and X-ray diffraction investigations of laser-irradiated CeO2 powders

The TG and DTA curves and diffractograms of powdered CeO₂ samples irradiated with a CO₂ laser beam with powers of 0.41–1.39 kW/cm² are presented. The laser treatment induced structural changes and probably generation of a metastable phase. X-ray diffraction coupled with thermal analysis was used to establish the structural modifications in the irradiated samples after heating.     

Rhenium complexes with pyrazoles. Synthesis and crystal structure of trans-[Re(O)(OMe)L4]Br2·L·4H2O (L is 3,5-dimethylpyrazole)

The first mononuclear Re^V complex with four pyrazole ligands, viz., [Re(O)(OMe)L₄]Br₂ (L is 3,5-dimethylpyrazole), and its molecular adduct with L, viz., [Re(O)(OMe)L₄]Br₂·L·4H₂O, were synthesized. The complex is resistant to hydrolysis in a neutral aqueous solution. The structure of the adduct was established by X-ray diffraction analysis.     

DL-蛋氨酸铋(Ⅲ)固体配合物的合成、表征和XRD数据指标化

许多氨基酸的金属配合物具有抗菌、抗炎、抗癌和拮抗作用等生物活性[1,2 ] 。铋的化合物在医药中也有着广泛的应用 ,如柠檬酸铋用于治疗胃病[3 ] ,某些铋的化合物也用于外科处理创伤和止血 ,为了寻找副作用小、疗效更好的抗溃疡新药 ,我们通过固 固反应合成了ＤＬ 蛋氨酸合铋 (Ⅲ )配合物。利用固相反应合成生物无机配合物 ,可有效地避免某些金属盐的水解 ,具有操作简单、副反应少、产率高等特点[4,5] 。1　实验部分1 1　主要仪器与试剂85 2型恒温磁力搅拌器 (上海司乐仪器厂 ) ,ＤＧＦ30型电热恒温干燥箱 (南京实验仪器厂 ) ,Ｄ2 60型恒…     

Simultaneous small-angle X-ray scattering and wide-angle X-ray diffraction

The simultaneous SAXS/WAXD technique is shown to provide an unambiguous method for following structural changes taking place during the programmed heating of a range of multiphase polymeric materials. Results are given for polyethylene, block copolyurethanes and block copolyesters containing liquid crystalline hard segments. UK Thermal methods Group Award Lecture     

Neutron powder diffraction study of tetragonal Li7La3Hf2O12 with the garnet-related type structure

We have successfully synthesized a polycrystalline sample of tetragonal garnet-related Li-ion conductor Li₇La₃Hf₂O₁₂ by solid state reaction. The crystal structure is analyzed by the Rietveld method using neutron powder diffraction data. The structure analysis identifies that tetragonal Li₇La₃Hf₂O₁₂ has the garnet-related type structure with a space group of I4₁/acd (no. 142). The lattice constants are a=13.106(2) Å and c=12.630(2) Å with a cell ratio of c/a=0.9637. The crystal structure of tetragonal Li₇La₃Hf₂O₁₂ has the garnet-type framework structure composed of dodecahedral La(1)O₈, La(2)O₈ and octahedral HfO₆. Li atoms occupy three types of crystallographic site in the interstices of this framework structure, where Li(1) atom is located at the tetrahedral 8a site, and Li(2) and Li(3) atoms are located at the distorted octahedral 16f and 32g sites, respectively. These Li sites are filled with the Li atom. The present tetragonal Li₇La₃Hf₂O₁₂ sample exhibits bulk Li-ion conductivity of σ_b=9.85×10⁻⁷ S cm⁻¹ and grain-boundary Li-ion conductivity of σ_gb=4.45×10⁻⁷ S cm⁻¹ at 300 K. The activation energy is estimated to be E_a=0.53 eV in the temperature range of 300-580 K.     

Reaction of hydroxyiminoacetophenone withp-toluenesulfonyl chloride and an X-ray diffraction study of the reaction product

2-Benzoyloxy-2-phenylmalononitrile is formed instead of the expected oxime tosylate in the reaction of hydroxyiminoacetophenone withp-toluenesulfonyl chloride. The structure of the product was confirmed unambiguously by X-ray diffraction analysis. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 872–874, April, 1997.     

Possibilities and limitations of synchrotron X-ray powder diffraction with double crystal and double multilayer monochromators for microscopic speciation studies

The performance of a combined microbeam X-ray fluorescence/X-ray powder diffraction (XRF/XRPD) measurement station at Hamburger Synchrotronstrahlungslabor (HASYLAB) Beamline L is discussed in comparison to that at European Synchrotron Radiation Facility (ESRF) ID18F/ID22. The angular resolution in the X-ray diffractograms is documented when different combinations of X-ray source, optics and X-ray diffraction detectors are employed. Typical angular resolution values in the range 0.3–0.5° are obtained at the bending magnet source when a ‘pink’ beam form of excitation is employed. A similar setup at European Synchrotron Radiation Facility beamlines ID18F and ID22 allows to reach angular resolution values of 0.1–0.15°. In order to document the possibilities and limitations for speciation of metals in environmental materials by means of Hamburger Synchrotronstrahlungslabor Beamline L X-ray fluorescence/X-ray powder diffraction setup, two case studies are discussed, one involved in the identification of the crystal phases in which heavy metals such as chromium, iron, barium and lead are present in polluted soils of an industrial site (Val Basento, Italy) and another involved in the speciation of uranium in depleted uranium particles (Ceja Mountains, Kosovo). In the former case, the angular resolution is sufficient to allow identification of most crystalline phases present while in the latter case, it is necessary to dispose of an angular resolution of ca. 0.2° to distinguish between different forms of oxidized uranium.