Terephthalate salts of dipositive cations

2002 ◽  
Vol 58 (5) ◽  
pp. 815-822 ◽  
Author(s):  
James A. Kaduk
Keyword(s):  
Rietveld Method ◽  
Metal Cations ◽  
Metal Coordination ◽  
Monoclinic Space Group ◽  
Average Difference ◽  
Synchrotron Powder Diffraction ◽  
Accuracy And Precision ◽  
Aromatic Carboxylates ◽  
Monte Carlo Simulated Annealing ◽  
Normal Strength

The crystal structures of M(C8H4O4)(H2O)2, M = Mg, Mn, Fe and Co, have been determined by applying Monte Carlo simulated annealing techniques to synchrotron powder diffraction data and refined by the Rietveld method using both synchrotron and laboratory powder data. These isostructural compounds crystallize in the monoclinic space group C2/c, with 18.2734 (9) ≤ a ≤ 18.7213 (13), 6.5186 (13) ≤ b ≤ 6.5960 (4), 7.2968 ≤ c ≤ 7.4034 (6) Å, 98.653 (2) ≤ β ≤ 99.675 (1)° and Z = 4. The structure consists of alternating layers (perpendicular to a) of terephthalate anions and octahedrally coordinated metal cations. The octahedra are isolated; each carboxylate bridges two metal cations. The equatorial metal coordination consists of four terephthalate O atoms and there are two axial water molecules. Both water-molecule H atoms participate in normal-strength hydrogen bonds to carboxylate O atoms. Quantum chemical calculations (using CASTEP) were used to determine the H-atom positions and analyze the hydrogen bonding and the metal coordination. Both the atomic charges and the M—O bond-overlap populations indicate that, despite the fact that these compounds are isostructural, the metal–terephthalate bonding is different. The bonding in the Mg complex is essentially ionic, while the M—O bonds in the Mn, Fe and Co complexes have significant covalent character. Comparison of a new Rietveld refinement of the structure of copper(II) terephthalate trihydrate with the reported single-crystal structure provides an opportunity to assess the accuracy and precision that can be expected from structures of aromatic carboxylates determined using X-ray powder data. The average difference between the bond distances in the two structures is 0.03 Å and the average difference in bond angles is only 1.1°.

Salts of aromatic carboxylates: the crystal structures of nickel(II) and cobalt(II) 2,6-naphthalenedicarboxylate tetrahydrate

2001 ◽  
Vol 34 (6) ◽  
pp. 710-714 ◽  
Author(s):  
James A. Kaduk ◽  
Jason A. Hanko
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Crystal Packing ◽  
Geometry Optimization ◽  
Metal Cations ◽  
Carboxyl Groups ◽  
Water Molecules ◽  
Triclinic Space Group ◽  
Aromatic Carboxylates ◽  
Monte Carlo Simulated Annealing

The crystal structures of isostructural 2,6-naphthalenedicarboxylate tetrahydrate salts of nickel(II) and cobalt(II) have been determined using Monte Carlo simulated annealing techniques and laboratory X-ray powder diffraction data. These compounds crystallize in the triclinic space groupP\bar{1}, withZ= 2;a= 10.0851 (4),b= 10.9429 (5),c= 6.2639 (3) Å, α = 98.989 (2), β = 87.428 (3), γ = 108.015 (2)°,V= 649.32 (5) Å3for [Ni(C12H6O4)(H2O)4], anda= 10.1855 (6),b= 10.8921 (6),c= 6.2908 (5) Å, α = 98.519 (4), β = 87.563 (4), γ = 108.304 (3)°,V= 655.28 (8) Å3for [Co(C12H6O4)(H2O)4]. The water-molecule H atoms were located by quantum chemical geometry optimization usingCASTEP. The structure consists of alternating hydrocarbon and metal/oxygen layers parallel to theacplane. Each naphthalenedicarboxylate anion bridges two metal cations; each carboxyl group is monodentate. The resulting structure contains infinite chains parallel to [111]. The octahedral coordination sphere of the metal cations containstranscarboxylates and four equatorial water molecules. The carboxyl groups are rotated by 15–20° out of the naphthalene plane. The metal/oxygen layers are characterized by an extensive hydrogen-bonding network. The orientations of the carboxyl groups are determined by the formation of short (O...O = 2.53 Å) hydrogen bonds between the carbonyl O atoms and theciswater molecules. Molecular mechanics energy minimizations suggest that coordination and hydrogen-bonding interactions are most important in determining the crystal packing.

Chemical accuracy and precision in Rietveld analysis: The crystal structure of cobalt(II) acetate tetrahydrate

1997 ◽  
Vol 12 (1) ◽  
pp. 27-39 ◽  
Author(s):  
James A. Kaduk ◽  
Walt Partenheimer
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Three Dimensional ◽  
Rietveld Analysis ◽  
Monoclinic Space Group ◽  
Acetate Tetrahydrate ◽  
Atomic Displacements ◽  
Synchrotron Powder Diffraction ◽  
Accuracy And Precision

The crystal structure of cobalt(II) acetate tetrahydrate, Co(C2H3O2)·4H2O, has been refined using single-crystal, laboratory powder, and synchrotron powder diffraction data, both individually and in various combinations. The compound crystallizes in the monoclinic space group P21/c, with a=4.80688(3), b=11.92012(7), c=8.45992(5) Å, β=94.3416(4)° at 27 °C, and Z=2. The crystal structure consists of discrete centrosymmetric trans-Co(C2H3O2)(H2O)4 complexes, linked by a three-dimensional network of hydrogen bonds. Each complex participates in 14 hydrogen bonds, 12 intermolecular, and 2 intramolecular. Compared to the single-crystal refinement, refinement of laboratory powder data yielded an average difference in bond distances of 0.02 Å, in bond angles of 3°, and in root mean square atomic displacements of 0.07 Å. The standard uncertainties of the bond distances were 0.01 Å, compared to the 0.001–0.002 Å in the single-crystal refinement. Refinement of the synchrotron powder data yielded improved accuracy and precision. It proved impossible to locate or refine hydrogen positions using a single-powder dataset, but the hydrogens could be refined using rigid groups in a joint refinement of the two powder datasets. Even from powder refinements, it is possible to obtain suitable accuracy and precision to distinguish C–O and C=O bonds, and to examine details of chemical bonding.

Accuracy and precision of analyses for total cholesterol as measured with the Reflotron cholesterol method.

1989 ◽  
Vol 35 (8) ◽  
pp. 1734-1739 ◽  
Author(s):  
P S Bachorik ◽  
R H Bradford ◽  
T Cole ◽  
I Frantz ◽  
A M Gotto ◽  
...  
Keyword(s):  
Plasma Cholesterol ◽  
Venous Blood ◽  
Reference Method ◽  
Capillary Blood ◽  
Average Difference ◽  
Blood Samples ◽  
Laboratory Values ◽  
Accuracy And Precision ◽  
Single Finger ◽  
Made In

Abstract We compared plasma cholesterol measurements made with the Boehringer Mannheim Reflotron reflectance photometric analyzer in 1298 capillary blood samples with measurements made in venous blood samples collected at the same time and analyzed in four standardized Lipid Research Clinics laboratories. The Reflotron measurements averaged 0.8% to 7.8% lower than the laboratory values. Correlations (r) between the two sets of measurements ranged from 0.92 to 0.96. In some samples, however, the Reflotron values differed from the laboratory values by greater than or equal to 12%; the cholesterol concentrations in these samples tended to be higher than in those for which better agreement was observed. The smaller negative biases were observed when test strips were used that were calibrated with reference to the Centers for Disease Control Reference Method for cholesterol. The agreement between sequential Reflotron values averaged less than or equal to 4.3%. There was an average difference of less than or equal to 1.0% between Reflotron measurements made in each of two sequential capillary blood samples taken from a single finger puncture.

The crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, solved ab initio from laboratory powder diffraction data

2014 ◽  
Vol 78 (2) ◽  
pp. 347-360 ◽  
Author(s):  
F. Colombo ◽  
J. Rius ◽  
O. Vallcorba ◽  
E. V. Pannunzio Miner
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Direct Methods ◽  
Hydroxyl Group ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Patterson Function ◽  
Unit Cell Dimensions

AbstractThe crystal structure of sarmientite, Fe23+ (AsO4)(SO4)(OH)·5H2O, from the type locality (Santa Elena mine, San Juan Province, Argentina), was solved and refined from in-house powder diffraction data (CuKα1,2 radiation). It is monoclinic, space group P21/n, with unit-cell dimensions a = 6.5298(1), b = 18.5228(4), c = 9.6344(3) Å, β = 97.444(2)º, V = 1155.5(5) Å3, and Z = 4. The structure model was derived from cluster-based Patterson-function direct methods and refined by means of the Rietveld method to Rwp = 0.0733 (X2 = 2.20). The structure consists of pairs of octahedral-tetrahedral (Fe−As) chains at (y,z) = (0,0) and (½,½), running along a. There are two symmetry-independent octahedral Fe sites. The Fe1 octahedra share two corners with the neighbouring arsenate groups. Both individual chains are related by a symmetry centre and joined by two symmetry-related Fe2 octahedra. Each Fe2 octahedron shares three corners with double-chain polyhedra (O3, O4 with arsenate groups; the O8 hydroxyl group with the Fe1 octahedron) and one corner (O11) with the monodentate sulfate group. The coordination of the Fe2 octahedron is completed by two H2O molecules (O9 and O10). There is also a complex network of H bonds that connects polyhedra within and among chains. Raman and infrared spectra show that (SO4)2− tetrahedra are strongly distorted.

Multiple Metal Coordination by Calixarenes: A Structure Determination of Relevance to the Use of Calixarenes as Solvent Extraction Agents

1999 ◽  
Vol 52 (5) ◽  
pp. 403 ◽  
Author(s):  
Zouhair Asfari ◽  
Jack M. Harrowfield ◽  
Pierre Thuéry ◽  
Martine Nierlich ◽  
Jacques E. Vicens
Keyword(s):  
Solvent Extraction ◽  
Structure Determination ◽  
Metal Coordination ◽  
Monoclinic Space Group ◽  
Sodium Ions ◽  
Space Group ◽  
Axial Coordination ◽  
Carboxylate Oxygen ◽  
Insoluble Material

An insoluble material formed in attempts to extract the copper(II) complex of (R,S)-5,5,7,12,12,14- hexamethyl-1,4,8,11-tetraazacyclotetradecane with the tetraanion of tetrakis(carboxymethyl) p-t-butylcalix[4]arene recrystallizes from pyridine with the composition [Cu(C16H36N4)] [Na2(C52H60O12)].2C5H5N.4·5H2O. The crystals are monoclinic, space group P 21/c (C52h, No. 14); a 26·8524(8), b 12·8151(2), c 25·6525(8) Å; β 115·356(1)°. The structure was refined on F2 (11379 reflections, 955 parameters), giving conventional R1 0·057 (wR2 0·118). The calixarene encapsulates two sodium ions and has only tenuous connection to the copper/macrocycle complex through axial coordination of one carboxylate oxygen.

Preparation and crystal structure of SbV1.50InIII0.50(PO4)3 and (SbV0.50InIII0.50)P2O7

2008 ◽  
Vol 23 (3) ◽  
pp. 232-240
Author(s):  
Abderrahim Aatiq ◽  
Rachid Bakri ◽  
Aaron Richard Sakulich
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Room Temperature ◽  
Rietveld Method ◽  
Monoclinic Space Group ◽  
Unit Cell Parameters ◽  
Orthorhombic System ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters

Synthesis and structure of two phosphates belonging to the ternary Sb2O5–In2O3–P2O5 system are realized. Structures of SbV1.50InIII0.50(PO4)3 and (SbV0.50InIII0.50)P2O7 phases, obtained by solid state reaction in air at 950 °C, were determined at room temperature from X-ray powder diffraction using the Rietveld method. SbV1.50InIII0.50(PO4)3 have a monoclinic (space group P21/n) distortion of the Sc2(W O4)3-type framework. Its structure is constituted by corner-shared SbO6 or InO6 octahedra and PO4 tetrahedra. Monoclinic unit cell parameters are a=11.801(2) Å, b=8.623(1) Å, c=8.372(1) Å, and β=90.93(1)°. (Sb0.50In0.50)P2O7 is isotypic with (Sb0.50Fe0.50)P2O7 and crystallizes in orthorhombic system (space group Pna21) with a=7.9389(1) Å, b=16.0664(2) Å, and c=7.9777(1) Å. Its structure is built up from corner-shared SbO6 or InO6 octahedra and P2O7 groups (two group-types). Each P2O7 group shares its six vertices with three SbO6 and three InO6 octahedra, and each octahedron is connected to six P2O7 groups.

scholarly journals (Na,□)5[MnO2]13nanorods: a new tunnel structure for electrode materials determinedab initioand refined through a combination of electron and synchrotron diffraction data

2016 ◽  
Vol 72 (6) ◽  
pp. 893-903 ◽  
Author(s):  
Enrico Mugnaioli ◽  
Mauro Gemmi ◽  
Marco Merlini ◽  
Michele Gregorkiewitz
Keyword(s):  
Diffraction Data ◽  
Electrode Materials ◽  
Rietveld Method ◽  
Unit Cell ◽  
Teller Distortion ◽  
Synchrotron Powder Diffraction ◽  
Jahn Teller ◽  
Crystal Electron ◽  
Jahn Teller Distortion ◽  
True Structure

(Nax□1 − x)5[MnO2]13has been synthesized withx= 0.80 (4), corresponding to Na0.31[MnO2]. This well known material is usually cited as Na0.4[MnO2] and is believed to have a romanèchite-like framework. Here, its true structure is determined,ab initio, by single-crystal electron diffraction tomography (EDT) and refined both by EDT data applying dynamical scattering theory and by the Rietveld method based on synchrotron powder diffraction data (χ2= 0.690,Rwp= 0.051,Rp= 0.037,RF2= 0.035). The unit cell is monoclinicC2/m,a= 22.5199 (6),b= 2.83987 (6),c= 14.8815 (4) Å, β = 105.0925 (16)°,V= 918.90 (4) Å3,Z= 2. A hitherto unknown [MnO2] framework is found, which is mainly based on edge- and corner-sharing octahedra and comprises three types of tunnels: per unit cell, two are defined by S-shaped 10-rings, four by egg-shaped 8-rings, and two by slightly oval 6-rings of Mn polyhedra. Na occupies all tunnels. The so-determined structure excellently explains previous reports on the electrochemistry of (Na,□)5[MnO2]13. The trivalent Mn3+ions concentrate at two of the seven Mn sites where larger Mn—O distances and Jahn–Teller distortion are observed. One of the Mn3+sites is five-coordinated in a square pyramid which, on oxidation to Mn4+, may easily undergo topotactic transformation to an octahedron suggesting a possible pathway for the transition among different tunnel structures.

scholarly journals Structures of FeII spin-crossover complexes from synchrotron powder-diffraction data

2004 ◽  
Vol 60 (5) ◽  
pp. 528-538 ◽  
Author(s):  
Eva Dova ◽  
René Peschar ◽  
Makoto Sakata ◽  
Kenichi Kato ◽  
Arno F. Stassen ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Structural Changes ◽  
Spin Crossover ◽  
Structural Model ◽  
Rietveld Method ◽  
Space Structure ◽  
Powder Diffraction Data ◽  
Synchrotron Powder Diffraction

Crystal structure determination and analysis have been carried out for the two spin-crossover compounds [Fe(teeX)6](BF4)2 (teeX is haloethyltetrazole; X = I: teei; X = Br: teeb), in both their high-spin (near 300 K) and their low-spin states (T = 90 K), using high-resolution powder-diffraction data collected at the ESRF (Grenoble, France) and SPring8 (Japan) synchrotron radiation facilities. The structures of teei have been solved using various direct-space structure determination techniques (grid search, genetic algorithm and parallel tempering) and refined with the Rietveld method using geometrical restraints. In the case of teeb, a structural model was found but a full refinement was not successful because of the presence of a significant amount of an amorphous component. Analysis of the structures (space group P21/c, Z = 2) and diffraction data, and the absence of phase transitions, show the overall structural similarity of these compounds and lead to the conclusion that the gradual spin-crossovers are likely to be accompanied by small structural changes only.

Neutron diffraction study of the crystallographic preferential orientation of metagabro mylonite

2013 ◽  
Vol 28 (S2) ◽  
pp. S276-S283
Author(s):  
M. Kučeráková ◽  
S. Vratislav ◽  
L. Kalvoda ◽  
M. Machek
Keyword(s):  
Czech Republic ◽  
Neutron Diffraction ◽  
Software Package ◽  
Rietveld Method ◽  
Direct Method ◽  
Preferential Orientation ◽  
Monoclinic Space Group ◽  
Structure Parameters ◽  
Space Group ◽  
Pole Figures

Neutron diffraction (ND) was used to investigate the crystallographic preferential orientation (CPO, texture) and structure parameters of four samples of metagabro mylonite collected from the eastern part of the metagabbro sheet at the Stare Mesto belt, Bohemia Massif, Czech Republic. The samples were selected to form a deformation-ordered series with the microstructure varying from non-deformed metagabbro protolith to strongly sheared ultramylonite and amphibole-rich ulramylonite. The specimens used in ND measurements were polished in form of an exact sphere with diameter 50 ± 0.1 mm. The obtained ND patterns were corrected for non-linear background and then evaluated using the Rietveld method implemented in the software package GSAS. Data recorded from powder preparded by milling material from the sampled rocks were used to refine the structure parameters of plagioclase (labradorite structure, triclinic space group C-1) and amphibole (monoclinic space group C2/m). The experiments were performed on the KSN-2 neutron diffractometer situated at the research reactor LVR-15 of the Nuclear Research Institute, plc. Rez, Czech Republic. The data sets of ND patterns measured on each of the four spherical specimens consisted of 90 diagrams collected for different diffraction vectors covering uniformly one orientation hemisphere of the specimen. Based on the collected data, the orientation distribution function (ODF) of crystalline grains was determined by Rietveld harmonic method (coefficients C(l,m,n) of the spherical harmonics expansion determined up to the order L = 8) for the two principal mineral phases - amphibole and plagioclase. The ODF was used to reconstruct (001), (020), (021), (110), (111) (plagioclase) and (001), (11-1), (020), (110), (200) (amphibole) pole figures (PFs). Direct method of ODF calculation implemented in ResMat software package was then used to calculate inverted pole figures (IPFs) of the plagioclase phase. CPO of the amphibole and plagioclase is then discussed in terms of the obtained texture indices and calculated PFs and IPFs and compared with data measured by other methods or available in literature.

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