Powder and single-crystal X-ray diffraction study of the structure of [Y(H2O)]2(C2O4)(CO3)2

2000 ◽  
Vol 56 (6) ◽  
pp. 998-1002 ◽  
Author(s):  
Thierry Bataille ◽  
Daniel Louër
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Direct Methods ◽  
Unit Cell ◽  
Powder Pattern ◽  
Orthorhombic Symmetry ◽  
Direction Parallel ◽  
Space Group

From powder pattern indexing it has been demonstrated that [Y(H2O)]2(C2O4)(CO3)2, yttrium oxalate carbonate, crystallizes with orthorhombic symmetry, space group C2221, a = 7.8177 (7), b = 14.943 (1), c = 9.4845 (7) Å, V = 1108.0 (1) Å3, Z = 4. This unit cell displays a doubling of the c parameter, arising from weak diffraction lines observed in the powder diffraction pattern, with respect to results reported in the literature. The crystal structure has been solved ab initio using direct methods from powder data and has been confirmed by additional single-crystal data collected with a CCD area detector. The overall crystal structure is similar for both unit cells, except that an alternation of the carbonate groups in the direction parallel to the screw axis is displayed in the larger cell, while with the suggested half unit cell (space group C2mm) the carbonate groups would show only one orientation. The unit-cell determination strategy from single-crystal diffraction, collected with Nonius CAD-4 and Nonius Kappa CCD diffractometers, is discussed with respect to the results extracted from the powder diffraction pattern. The study demonstrates the power and usefulness of the full trace of a powder pattern for the detection of subtle structure details.

Revisiting the crystal structure of [Co(NH3)5Cl]Cl2 using synchrotron powder diffraction: to what extent single-crystal diffraction from 1960s got it right?

2017 ◽  
Vol 32 (3) ◽  
pp. 179-186 ◽  
Author(s):  
S. Mohamud ◽  
S. Pagola
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Crystal Packing ◽  
Direct Methods ◽  
Rietveld Analysis ◽  
Single Crystal Diffraction ◽  
Space Group ◽  
Synchrotron Powder Diffraction ◽  
Structure Description

The crystal structure of the purpureo salt, [Co(NH3)5Cl]Cl2, first reported in 1963 and later revised in 1968 (in both cases from single-crystal diffraction) in the space group Pnma (No. 62), has been recently re-examined from synchrotron X-ray powder diffraction using direct methods and the software EXPO2013. The comparison of the Rietveld analysis results using the two published models and the atomic coordinates obtained from powders leads to an improved crystal structure description in the lower symmetry space group Pn21a (No. 33). As a result, the overall atom connectivity and crystal packing remain similar; however, the symmetry and internal geometry of the coordination complex are changed. The distortions from an idealized geometry in Pnma (No. 62) are likely because of energetically favorable hydrogen-bonding motifs in the crystal. The three models are compared, and their validity and limitations are discussed.

Phasing methods for powder data

2013 ◽  
Author(s):  
Carmelo Giacovazzo
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Ab Initio ◽  
Powder Diffraction ◽  
Powder Pattern ◽  
Inorganic Crystal Structure Database ◽  
Space Group ◽  
Structure Solution ◽  
Group A ◽  
Basic Features

Powder diffractometry plays (and will probably continue to play in the near future) a central role in research and technology, because it allows us to investigate materials which are not available as a single crystal of adequate size and quality. Therefore, recently, much effort has been devoted to the development of powder diffraction. Improvements include the design of better instruments (e.g. optimized synchrotron radiation lines, time-of-flight technology at pulsed neutron sources, optics, generators, detectors), as well as more sophisticated methods for data analysis. As a result, in favourable cases, high quality powder patterns of proteins may be collected which contain sufficient information to allow identification of the unit cell and of the space group, a result unthinkable 30 years ago. This has opened the way for qualitative analysis and study of the polymorphism of macromolecules (Margiolaki et al., 2005; Collings et al., 2010). Advances in the experimental and the theoretical aspects of powder crystallography have been able to reduce losses of information from a powder pattern with respect to single crystal data, and have made ab initio crystal structure solution from powder experiments possible. The reader may deduce the increasing popularity of powder techniques from: (i) Table 1.11, where, among the CSD (Cambridge Structural Database), entries on 1 January 2012, 2354 powder diffraction studies were counted; (ii) Figure 12.1, where the cumulative statistics (up to the year 2006) on the number of structures solved via powder diffraction data is shown (SDPD database); (iii) Figure 12.2, where the statistics on the number of studies in the ICDD (Inorganic Crystal Structure Database) (to the year 2005) for different types of data is given. For the powder case, 21 472 cases are counted for which powder data have been used, mostly for refinement purposes. In this chapter, we will neglect experimental aspects, unless unrelated to the phasing problem. We will describe in Sections 12.2 to 12.5, the basic features of powder pattern diagrams, and in Sections 12.6 and 12.7, the procedures for full pattern indexing and space group determination. Ab initio phasing will be treated in Section 12.8 and non-ab initio methods in Section 12.9. The combination of anomalous dispersion techniques with powder methods is postponed to Section 15.9.

Powder Diffraction Data for Nitroguanidine, C(NH2)2NNO2

1991 ◽  
Vol 6 (3) ◽  
pp. 164-165
Author(s):  
E.K. Vasil'ev ◽  
A.N. Sapozhnivov ◽  
Z.A. Dobronravova ◽  
L.I. Vereshchagin
Keyword(s):  
Single Crystal ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Space Group ◽  
Cell Data ◽  
Unit Cell Data

AbstractA powder diffraction pattern and unit cell data for nitroguanidine, C(NH2)2NNO2 are presented. The orthorhombic space group Fdd2 (43) has been confirmed by single crystal methods.

X-ray powder diffraction data for estra-4,9-diene-3,17-dione, C18H22O2

2020 ◽  
Vol 35 (4) ◽  
pp. 282-285
Author(s):  
Zhicheng Zha ◽  
Ting Tang ◽  
Xiaoyan Bian ◽  
Qing Wang
Keyword(s):  
Single Crystal ◽  
Cell Volume ◽  
Powder Diffraction ◽  
Structure Data ◽  
Diffraction Data ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray

X-ray powder diffraction data for estra-4,9-diene-3,17-dione, C18H22O2, are reported [a = 9.236(7) Å, b = 10.294(4) Å, c = 15.471(1) Å, unit cell volume V = 1471.11 Å3, Z = 4, and space group P212121]. All measured lines were indexed and are consistent with the P212121 space group. No detectable impurities were observed. The single-crystallographic data of the compound are also reported [a = 9.2392(7) Å, b = 10.2793(5) Å, c = 15.4822(7) Å, unit cell volume V = 1470.37(15) Å3, Z = 4, and space group P212121]. Both single-crystal and powder diffraction methods can get the similar structure data.

X-ray powder diffraction analysis of 2-exo-(β-pyridyl)-6-exo-phenyl-7-oxa-1-azabicyclo[2.2.1]heptane

2003 ◽  
Vol 18 (1) ◽  
pp. 47-49
Author(s):  
J. C. Poveda ◽  
J. A. Henao ◽  
J. A. Pinilla ◽  
V. V. Kouznetsov ◽  
C. Ochoa
Keyword(s):  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Heterocyclic System ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

The X-ray powder diffraction pattern for a bridgehead heterocyclic system was determined. 2-exo-(β-pyridyl)-6-exo-phenyl-7-oxa-1-azabicyclo[2.2.1]heptane, C16H16N2O, is triclinic with refined unit cell parameters a=1.1012(2), b=1.3950(2), c=1.0074(3) nm, α=111.09(2)°, β=104.97(2)°, γ=77.38(2)°, V=1.3813(3) nm3, Z=4, and Dx=1.212 g/cm3 with space group P-1 (No. 2).

Embreyite: structure determination, chemical formula and comparative crystal chemistry

2018 ◽  
Vol 82 (2) ◽  
pp. 275-290 ◽  
Author(s):  
Vadim M. Kovrugin ◽  
Oleg I. Siidra ◽  
Igor V. Pekov ◽  
Nikita V. Chukanov ◽  
Dmitry A. Khanin ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Microprobe Analysis ◽  
Direct Methods ◽  
Structural Similarity ◽  
Structural Type ◽  
Unit Cell ◽  
Single Crystal Xrd ◽  
Cell Parameters ◽  
Distorted Octahedra

ABSTRACTEmbreyite from the Berezovskoe, Urals, Russia, was studied by the means of powder X-ray diffraction (XRD), single-crystal XRD, infrared spectroscopy and microprobe analysis. The empirical formula of embreyite obtained on the basis of microprobe analysis is Pb1.29Cu0.07Cr0.52P0.43O4(without taking into account the presence of H2O). An examination of single-crystal XRD frames of the tested crystals cut from embreyite intergrowths revealed split reflection spots of weak intensities, even after a long exposure time. The crystal structure of embreyite (monoclinic,C2/m,a= 9.802(16),b= 5.603(9),c= 7.649(12) Å, β = 114.85(3)oandV= 381.2(11) Å3) has been solved by direct methods and refined toR1= 0.050 for 318 unique observed reflections. The powder XRD patterns of the holotype embreyite and the fresh material studied are close in bothdvalues and the intensities match the pattern calculated from the structural single-crystal XRD data. The unit-cell parameters were re-calculated for the holotype sample using a new cell setting and correspondinghklindices. The crystal structure of embreyite is based on layers formed by corner-sharing mixed chromate-phosphate tetrahedra and PbO6distorted octahedra. The interlayer space is filled by disordered Pb2+and Cu2+cations. Generally, the crystal structure of embreyite can be referred to the structural type of palmierite. {Pb[(Cr,P)O4]2]} layers in embreyite are similar in topology to those in yavapaiite-type compounds. The general formula of embreyite can be represented as (Pbx$M_y^{2 +} $□1–x–y)2{Pb[(Cr,P)O4]2}(H2O)n, whereM2+= Cu and Zn and 0.5 ≤x+y≤ 1, or, in the simplified form: (Pb,Cu,□)2{Pb[(Cr,P)O4]2}(H2O)n. The simplified formula of embreyite is similar in stoichiometry to vauquelinite and may explain the existence of the solid-solution series. The determination of the crystal structure of embreyite may also help to resolve the crystal chemical nature of cassedanneite. The XRD pattern of cassedanneite contains a distinct reflection withd= 13.9 Å, forbidden for the embreyite unit cell. This feature may indicate the doubling of thecunit-cell parameter of cassedanneite in comparison with embreyite. We assume that cassedanneite has structural similarity to embreyite with, presumably, a disordered distribution of Cr and V.

The crystal structure of trisodium hexachlororhodate (Na3RhCl6)

2018 ◽  
Vol 33 (1) ◽  
pp. 62-65
Author(s):  
Martin Etter
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Structure Type ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

Commercially available trisodium hexachlororhodate (Na3RhCl6) was dehydrated and characterized by laboratory X-ray powder diffraction. The crystal structure is isostructural to the Na3CrCl6 structure type with space group P$\bar 31$c. Unit-cell parameters are a = 6.8116(1) Å, c = 11.9196(2) Å, V = 478.95(2) Å3, and Z = 2.

Redefinition of satimolite

2018 ◽  
Vol 82 (5) ◽  
pp. 1033-1047 ◽  
Author(s):  
Igor V. Pekov ◽  
Natalia V. Zubkova ◽  
Dmitry A. Ksenofontov ◽  
Nikita V. Chukanov ◽  
Vasiliy O. Yapaskurt ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Direct Methods ◽  
Salt Dome ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Octahedral Clusters

ABSTRACTThe borate mineral satimolite, which was first described in 1969 and remained poorly-studied until now, has been re-investigated (electron microprobe analysis, single-crystal and powder X-ray diffraction studies, crystal-structure determination, infrared spectroscopy) and redefined based on the novel data obtained for the holotype material from the Satimola salt dome and a recently found sample from the Chelkar salt dome, both in North Caspian Region, Western Kazakhstan. The revised idealized formula of satimolite is KNa2(Al5Mg2)[B12O18(OH)12](OH)6Cl4·4H2O (Z = 3). The mineral is trigonal, space group R$\bar{3}$m, unit-cell parameters are: a = 15.1431(8), c = 14.4558(14) Å and V = 2870.8(4) Å3 (Satimola) and a = 15.1406(4), c = 14.3794(9) Å and V = 2854.7(2) Å3 (Chelkar). The crystal system and unit-cell parameters are quite different from those reported previously. The crystal structure of the sample from Chelkar was solved based on single-crystal data (direct methods, R = 0.0814) and the structure of the holotype from Satimola was refined on a powder sample by the Rietveld method (Rp = 0.0563, Rwp = 0.0761 and Rall = 0.0667). The structure of satimolite is unique for minerals. It contains 12-membered borate rings [B12O18(OH)12] in which BO3 triangles alternate with BO2(OH)2 tetrahedra sharing common vertices, and octahedral clusters [M7O6(OH)18] with M = Al5Mg2 in the ideal case, with sharing of corners between rings and clusters to form a three-dimensional heteropolyhedral framework. Each borate ring is connected with six octahedral clusters: three under the ring and three over the ring. Large ellipsoidal cages in the framework host Na and K cations, Cl anions and H2O molecules.

scholarly journals Structure determination from X-ray powder diffraction data at low resolution

2014 ◽  
Vol 70 (a1) ◽  
pp. C143-C143
Author(s):  
Hongliang Xu
Keyword(s):  
Single Crystal ◽  
Diffraction Pattern ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Direct Methods ◽  
Atomic Resolution ◽  
Powder Diffraction Data ◽  
Low Resolution

Knowledge of the structural arrangement of atoms in solids is necessary to facilitate the study of their properties. The best and most detailed structural information is obtained when the diffraction pattern of a single crystal a few tenths of a millimeter in each dimension is analyzed, but growing high-quality crystals of this size is often difficult, sometimes impossible. However, many crystallization experiments that do not yield single crystals do yield showers of randomly oriented micro-crystals that can be exposed to X-rays simultaneously to produce a powder diffraction pattern. Direct Methods routinely solve crystal structures when single-crystal diffraction data are available at atomic resolution (1.0-1.2Å), but fail to determine micro-crystal structures due to reflections overlapping and low-resolution powder diffraction data. By artificially and intelligently extending the measured data to atomic resolution, we have successfully solved structures having low-resolution diffraction data that were hard to solve by other direct-method based computation procedures. The newly developed method, Powder Shake-and-Bake, is implemented in a computer program PowSnB. PowSnB can be incorporated into the state-of-the-art software package EXPO that includes powder data reduction, structure determination and structure refinement. The new combination could have potential to solve structures that have never been solved before by direct-methods approach.

Crystal Data for LnKFe (CN)6·4H20, Ln=La, Ce, Pr, and Nd Compound

1989 ◽  
Vol 4 (2) ◽  
pp. 101-102 ◽  
Author(s):  
D.F. Mullica ◽  
E.L. Sappenfield
Keyword(s):  
Cell Volume ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Ionic Radius ◽  
Unit Cell Volume ◽  
Unit Cell ◽  
Crystal Data ◽  
Space Group ◽  
X Ray

AbstractCrystal data and a representative X-ray powder diffraction pattern are reported for a series of isomorphous compounds, LnKFe(CN)6.4H2O where Ln = La, Ce, Pr and Nd. They crystallize in the hexagonal space group P63/m (176) with Z = 2. A plot of the unit cell volume (V) versus the cube of the Ln ionic radius (r3) yields linearity with a correlation coeficient of 0.9998.

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