scholarly journals Crystal structure of barium perchlorate anhydrate, Ba(ClO4)2, from laboratory X-ray powder data

2015 ◽  
Vol 71 (6) ◽  
pp. 588-591 ◽  
Author(s):  
Jeonghoo H. Lee ◽  
Ji Hoon Kang ◽  
Sung-Chul Lim ◽  
Seung-Tae Hong
Keyword(s):  
Crystal Structure ◽  
Three Dimensional ◽  
Structure Type ◽  
Site Symmetry ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
Orthorhombic Space Group ◽  
Special Position ◽  
X Ray ◽  
Barium Perchlorate

The previously unknown crystal structure of barium perchlorate anhydrate, determined and refined from laboratory X-ray powder diffraction data, represents a new structure type. The title compound was obtained by heating hydrated barium perchlorate [Ba(ClO4)2·xH2O] at 423 Kin vacuofor 6 h. It crystallizes in the orthorhombic space groupFddd. The asymmetric unit contains one Ba (site symmetry 222 on special position 8a), one Cl (site symmetry 2 on special position 16f) and two O sites (on general positions 32h). The structure can be described as a three-dimensional polyhedral network resulting from the corner- and edge-sharing of BaO12polyhedra and ClO4tetrahedra. Each BaO12polyhedron shares corners with eight ClO4tetrahedra, and edges with two ClO4tetrahedra. Each ClO4tetrahedron shares corners with four BaO12polyhedra, and an edge with the other BaO12polyhedron.

scholarly journals Crystal structure of calcium perchlorate anhydrate, Ca(ClO4)2, from laboratory powder X-ray diffraction data

2018 ◽  
Vol 74 (4) ◽  
pp. 514-517 ◽  
Author(s):  
Dongmin Lee ◽  
Hyeri Bu ◽  
Dohwan Kim ◽  
Jooeun Hyoung ◽  
Seung-Tae Hong
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Wyckoff Position ◽  
Hydrated Calcium

The crystal structure of calcium perchlorate anhydrate was determined from laboratory X-ray powder diffraction data. The title compound was obtained by heating hydrated calcium perchlorate [Ca(ClO4)2·xH2O] at 623 K in air for 12 h. It crystallizes in the orthorhombic space group Pbca and is isotypic with Ca(AlD4)2. The asymmetric unit contains one Ca, two Cl and eight O sites, all on general sites (Wyckoff position 8c). The crystal structure consists of isolated ClO4 − tetrahedra and Ca2+ cations. The Ca2+ cation is coordinated by eight O atoms of eight symmetry-related ClO4 − tetrahedra within a distorted square-antiprismatic environment.

The seriesRE5Li2Sn7(RE= Ce, Pr, Nd, Sm) revisited: crystal structure ofRE5Li2−xSn7+x[0 ≤x≤ 0.03 (1)]

2013 ◽  
Vol 70 (1) ◽  
pp. 2-6 ◽  
Author(s):  
Julien P. A. Makongo ◽  
Svilen Bobev
Keyword(s):  
Crystal Structure ◽  
Structure Type ◽  
Intermetallic Phases ◽  
Asymmetric Unit ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Pearson Symbol ◽  
High Temperature Reactions ◽  
Compositional Variations

The series ofRE5Li2Sn7(RE= Ce–Sm) compounds were synthesized by high-temperature reactions and structurally characterized by single-crystal X-ray diffraction. The compounds are pentacerium dilithium heptastannide, Ce5Li1.97Sn7.03, pentapreseodymium dilithium heptastannide, Pr5Li1.98Sn7.02, pentaneodymium dilithium heptastannide, Nd5Li1.99Sn7.01, and pentasamarium dilithium heptastannide, Sm5Li2Sn7. All five compounds crystallize in the chiral orthorhombic space groupP212121(No. 19), which is relatively uncommon among intermetallic phases. The structure belongs to the Ce5Li2Sn7structure type (Pearson symboloP56), with 14 unique atoms in the asymmetric unit. Minor compositional variations exist, due to the mixed occupancy of Li and Sn atoms at one of the Li sites. The small occupational disorder is most evident forRE5Li2−xSn7+x(RE= Ce, Pr;x≃ 0.03), while the structure of Nd5Li2Sn7and Sm5Li2Sn7show no apparent disorder.

Crystal structure of calcium zirconium diorthophosphate, CaZr(PO4)2

2003 ◽  
Vol 18 (4) ◽  
pp. 296-300 ◽  
Author(s):  
Koichiro Fukuda ◽  
Kazuko Fukutani
Keyword(s):  
Crystal Structure ◽  
Rietveld Method ◽  
Three Dimensional ◽  
Direct Methods ◽  
Dimensional Structure ◽  
Pentagonal Bipyramid ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
X Ray ◽  
Reliability Indices

The crystal structure of CaZr(PO4)2 was determined from conventional X-ray powder diffraction data using direct methods, and it was further refined by the Rietveld method. The structure was orthorhombic (space group P212121, Z=4) with a=1.448 76(4), b=0.672 13(1), c=0.623 47(2) nm, and V=0.607 10(3) nm3. Final reliability indices were Rwp=6.49%, RB=2.43%, and S=1.32. The Ca atom is sevenfold coordinated, and the Ca atom and surrounding oxygen atoms form a distorted capped octahedron with a mean Ca–O distance of 0.243 nm. The ZrO7 coordination polyhedron is a distorted pentagonal bipyramid with a mean Zr–O distance of 0.216 nm. CaO7, ZrO7, and PO4 polyhedra share edges to form infinite chains with the composition [CaO3ZrO3P2O8]12− along the [010]. Individual chains are linked together, forming a two-dimensional sheet parallel to (100). These sheets are stacked in the [100] direction to form a three-dimensional structure.

scholarly journals Trisodium citrate, Na3(C6H5O7)

2016 ◽  
Vol 72 (6) ◽  
pp. 793-796 ◽  
Author(s):  
Alagappa Rammohan ◽  
James A. Kaduk
Keyword(s):  
Crystal Structure ◽  
Density Functional Theory ◽  
Density Functional ◽  
Three Dimensional ◽  
Trisodium Citrate ◽  
Powder Diffraction Data ◽  
Asymmetric Unit ◽  
Functional Theory ◽  
X Ray ◽  
Methylene Group

The crystal structure of anhydrous trisodium citrate, Na3(C6H5O7), has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory (DFT). There are two independent five-coordinate Na+and one six-coordinate Na+cations in the asymmetric unit. The [NaO5] and [NaO6] polyhedra share edges and corners to form a three-dimensional framework. There are channels parallel to theaandbaxes in which the remainder of the citrate anions reside. The only hydrogen bonds are an intramolecular one between the hydroxy group and one of the terminal carboxylate O atoms and an intermolecular one between a methylene group and the hydroxyl O atom.

Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

2021 ◽  
pp. 1-3
Author(s):  
Carina Schlesinger ◽  
Edith Alig ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Commercial Sample ◽  
One Dimensional ◽  
X Ray ◽  
Hydrogen Bond Pattern

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

scholarly journals Redetermination of the crystal structure of RhPb2 from single-crystal X-ray diffraction data, revealing a rhodium deficiency

2021 ◽  
Vol 77 (12) ◽  
Author(s):  
Takashi Mochiku ◽  
Yoshitaka Matsushita ◽  
Nikola Subotić ◽  
Takanari Kashiwagi ◽  
Kazuo Kadowaki
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Type ◽  
Site Symmetry ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Displacement Parameters ◽  
Slight Deficiency

RhPb2 (rhodium dilead) is a superconductor crystallizing in the CuAl2 structure type (space group I4/mcm). The Rh and Pb atoms are located at the 4a (site symmetry 422) and 8h (m.2m) sites, respectively. The crystal structure is composed of [RhPb8] antiprisms, which share their square faces along the c axis and the edges in the direction perpendicular to the c axis. We have succeeded in growing single crystals of RhPb2 and have re-determined the crystal structure on basis of single-crystal X-ray diffraction data. In comparison with the previous structure studies using powder X-ray diffraction data [Wallbaum (1943). Z. Metallkd. 35, 218–221; Havinga et al. (1972). J. Less-Common Met. 27, 169–186], the current structure analysis of RhPb2 leads to more precise unit-cell parameters and fractional coordinates, together with anisotropic displacement parameters for the two atoms. In addition and likewise different from the previous studies, we have found a slight deficiency of Rh in RhPb2, leading to a refined formula of Rh0.950 (9)Pb2.

Ab initio structure determination of nanosized θ-KAlF4 with edge-sharing AlF6 octahedra

2009 ◽  
Vol 24 (3) ◽  
pp. 185-190 ◽  
Author(s):  
A. Le Bail
Keyword(s):  
Crystal Structure ◽  
Ab Initio ◽  
Fluorite Structure ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Orthorhombic Unit Cell ◽  
Common Edge ◽  
X Ray ◽  
Ab Initio Structure

θ-KAlF4 is a new nanosized potassium tetrafluoroaluminate metastable polymorph (13×18×55 nm3). The crystal structure is solved ab initio from X-ray powder diffraction data in direct space [orthorhombic unit cell with a=8.3242(3) Å, b=7.2502(3) Å, c=11.8875(4) Å, V=717.44(5) Å3, Z=8, and space group Pnma]. This new structure type, unique in the whole AIMIIIF4 family, is related to the fluorite structure and consists of AlF6 octahedra linked via a common edge forming a bioctahedral motif which is trans-connected through the corner-shared fluorine, resulting in the formation of infinite ladderlike double file of octahedra ([Al2F8]2−)n running along the b axis.

scholarly journals Dilithium disodium nickel(II) cyclohexaphosphate dodecahydrate, Li2Na2NiP6O18·12H2O

2012 ◽  
Vol 68 (8) ◽  
pp. i62-i63 ◽  
Author(s):  
Sonia Abid ◽  
Salem S. Al-Deyab ◽  
Mohamed Rzaigui
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Chair Conformation ◽  
Internal Symmetry ◽  
Site Symmetry ◽  
Special Position ◽  
Tetrahedral Environment ◽  
Anionic Charge

The crystal structure of Li2Na2NiP6O18·12H2O is characterized by the presence of six-membered P6O186−phosphate ring anions (internal symmetry -1) having a chair conformation and three different cations,viz.Li+, Na+and Ni2+, to counterbalance the anionic charge. All atoms are in general positions except for nickel, which lies on a special position with site symmetry 2. Lithium has a tetrahedral environment (LiO4), and sodium and nickel have octahedral environments [NaO6and Ni(H2O)6, respectively]. The P6O18rings are linkedviacorner sharing by NaO6octahedra and LiO4tetrahedra to form a three-dimensional framework presenting tunnels running along [010] in which the six-coordinated Ni2+cations are located. The structure is stabilized by a network of O—H...O hydrogen bonds.

Crystal structure of (Z)-cefprozil monohydrate, C18H19N3O5S(H2O)

2019 ◽  
Vol 34 (4) ◽  
pp. 379-388
Author(s):  
Zachary R. Butler ◽  
James A. Kaduk ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Density Functional ◽  
Three Dimensional ◽  
Ion Pair ◽  
Powder Diffraction Data ◽  
Powder Diffraction File ◽  
X Ray ◽  
Dimensional Network ◽  
Acid Proton

The crystal structure of cefprozil monohydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Cefprozil monohydrate crystallizes in space group P21 (#4) with a = 11.26513(6), b = 11.34004(5), c = 14.72649(11) Å, β = 90.1250(4)°, V = 1881.262(15) Å3, and Z = 4. Although a reasonable fit was obtained using an orthorhombic model, closer examination showed that many peaks were split and/or had shoulders, and thus the true symmetry was monoclinic. DFT calculations revealed that one carboxylic acid proton moved to an amino group. The structure thus contains one ion pair and one pair of neutral molecules. This protonation was confirmed by infrared spectroscopy. There is an extensive array of hydrogen bonds resulting in a three-dimensional network. The powder pattern has been submitted to ICDD® for inclusion in the Powder Diffraction File™.

scholarly journals Reinvestigation of trilithium divanadium(III) tris(orthophosphate), Li3V2(PO4)3, based on single-crystal X-ray data

2013 ◽  
Vol 69 (2) ◽  
pp. i11-i12 ◽  
Author(s):  
Yongho Kee ◽  
Hoseop Yun
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Title Compound ◽  
Three Dimensional ◽  
Structure Type ◽  
Powder Diffraction Data ◽  
Charge Balance ◽  
X Ray ◽  
Anisotropic Displacement Parameters

The structure of Li3V2(PO4)3has been reinvestigated from single-crystal X-ray data. Although the results of the previous studies (all based on powder diffraction data) are comparable with our redetermination, all atoms were refined with anisotropic displacement parameters in the current study, and the resulting bond lengths are more accurate than those determined from powder diffraction data. The title compound adopts the Li3Fe2(PO4)3structure type. The structure is composed of VO6octahedra and PO4tetrahedra by sharing O atoms to form the three-dimensional anionic framework∞3[V2(PO4)3]3−. The positions of the Li+ions in the empty channels can vary depending on the synthetic conditions. Bond-valence-sum calculations showed structures that are similar to the results of the present study seem to be more stable compared with others. The classical charge balance of the title compound can be represented as [Li+]3[V3+]2[P5+]3[O2−]12.

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