The Crystal Structure of [Mg2(H2O)6(HCO3)3]+Cl–, Containing a Magnesium-based Hetero-polycation

2008 ◽  
Vol 63 (12) ◽  
pp. 1347-1351 ◽  
Author(s):  
Robert E. Dinnebier ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Resolution ◽  
Structural Phase Transition ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Phase ◽  
Close Packing ◽  
Powder Diffraction Data ◽  
Hydrogen Carbonate

The crystal structure of di-magnesium hexahydrate trihydrogencarbonate chloride, [Mg2(H2O)6- (HCO3)3]+Cl−, has been determined from high-resolution laboratory powder diffraction data (lattice parameters at r. t.: a = 8.22215(2), c = 39.5044(2) Å, V = 2312.85(2) Å3, space group R3̄̄c, Z = 6). The crystal structure of [Mg2(H2O)6(HCO3)3]+Cl− is built up of alternating sheets of Cl− anions and complex [Mg2(H2O)6(HCO3)3]+ cations consisting of two Mg(OH2)3O3 octahedra interconnected by three disordered hydrogen carbonate groups. The packing can be described as a cubic close packing of [Mg2(H2O)6(HCO3)3]+ cations with the Cl− anions filling all octahedral voids. In the temperature range from r. t. up to decomposition, which takes place in the range 398 K < T < 413 K, no structural phase transition occurs.

Cs2Zn(CN)4: a first example of a non-cyano spinel of composition A2M(CN)4 with A=alkali metal and M=group 12 metal

2020 ◽  
Vol 75 (1-2) ◽  
pp. 97-103
Author(s):  
Melanie Werker ◽  
Uwe Ruschewitz
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Resolution ◽  
Alkali Metal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Synchrotron Powder Diffraction ◽  
Group 12 ◽  
Reversible Melting

AbstractThe crystal structure of monoclinic Cs2Zn(CN)4 (C2/c, Z = 4) was solved and refined from high-resolution synchrotron powder diffraction data (ESRF: Swiss-Norwegian beamline). In contrast to all other known cyanides of composition A2M(CN)4 with A = alkali metal and M = group 12 metal, which crystallize in cubic or rhombohedrally distorted spinel variants and thus with A+ in an octahedral coordination, the Cs+ cation in Cs2Zn(CN)4 shows an eight-fold coordination by CN− anions of the [Zn(CN)4]2− tetrahedra. Upon heating, no phase transition is observed. Instead, a reversible melting at approx. T = 380°C occurs.

Combined Rietveld and stereochemical restraint refinement of a protein crystal structure

1999 ◽  
Vol 32 (6) ◽  
pp. 1084-1089 ◽  
Author(s):  
R. B. Von Dreele
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Tertiary Structure ◽  
Protein Crystal ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Protein Crystal Structure

By combining high-resolution X-ray powder diffraction data and stereochemical restraints, Rietveld refinement of protein crystal structures has been shown to be feasible. A refinement of the 1261-atom protein metmyoglobin was achieved by combining 5338 stereochemical restraints with a 4648-step (dmin= 3.3 Å) powder diffraction pattern to give the residualsRwp= 2.32%,Rp= 1.66%,R(F2) = 3.10%. The resulting tertiary structure of the protein is essentially identical to that obtained from previous single-crystal studies.

Crystal structure determination of mebendazole form A using high‐resolution synchrotron x‐ray powder diffraction data

2010 ◽  
Vol 99 (4) ◽  
pp. 1734-1744 ◽  
Author(s):  
Fabio Furlan Ferreira ◽  
Selma Gutierrez Antonio ◽  
Paulo César Pires Rosa ◽  
Carlos de Oliveira Paiva‐Santos
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Powder Diffraction Data ◽  
X Ray

Crystal structure of the inclusion complex of β-cyclodextrin with mefenamic acid from high-resolution synchrotron powder-diffraction data in combination with molecular-mechanics calculations

2002 ◽  
Vol 58 (6) ◽  
pp. 1036-1043 ◽  
Author(s):  
Mihaela M. Pop ◽  
Kees Goubitz ◽  
Gheorghe Borodi ◽  
Mircea Bogdan ◽  
Dirk J. A. De Ridder ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Inclusion Complex ◽  
Molecular Mechanics ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Mefenamic Acid ◽  
Powder Diffraction Data ◽  
Molecular Mechanics Calculations ◽  
Synchrotron Powder Diffraction

The crystal structure of the inclusion complex of β-cyclo-dextrin with mefenamic acid has been determined from a combination of high-resolution synchrotron powder-diffraction data and molecular-mechanics calculations. A grid search indicates two possible solutions, which are corroborated by molecular-mechanics calculations, while Rietveld-refinement results suggest the crystal structure that is more likely to be formed in the solid state. Mefenamic acid is partially included in β-cyclodextrin with either the xylyl or the benzoic-acid moiety being inside its cavity. In both solutions mefenamic acid and β-cyclodextrin form a monomeric complex in a herringbone packing scheme.

Crystal Structure of Melaminium Orthophosphate from High-Resolution Synchrotron Powder-Diffraction Data

2004 ◽  
Vol 87 (7) ◽  
pp. 1894-1905 ◽  
Author(s):  
Dirk J. A. De Ridder ◽  
Kees Goubitz ◽  
Vladimir Brodski ◽  
René Peschar ◽  
Henk Schenk
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Powder Diffraction Data ◽  
Synchrotron Powder Diffraction

Crystal Structure and Thermal Behaviour of Er2(SeO4)3 · 8H2O

2004 ◽  
Vol 59 (9) ◽  
pp. 958-962 ◽  
Author(s):  
Ina Krügermann ◽  
Mathias S. Wickleder
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Single Crystals ◽  
Thermal Behaviour ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Monoclinic Space Group ◽  
Powder Diffraction Data ◽  
Temperature Dependent ◽  
Selenic Acid

Single crystals of Er2(SeO4)3 ・ 8H2O were obtained by dissolving Er2O3 in selenic acid. The selenate crystallizes in the monoclinic space group C2/c (Z = 4, a = 1372.8(2), b = 687.51(7), c = 1860.2(3) pm, β = 101.85(2)◦, Rall = 0.0518) and contains the Er3+ ions in eightfold coordination of oxygen atoms that belong to two crystallographically different SeO42− ions and to four H2O molecules. According to DTA/TG measurements and temperature dependent powder diffraction data, Er2(SeO4)3 ・8H2O decomposes in several steps yielding finally Er2O3. Er2(SeO4)3 and Er2(SeO3)3 could be identified as intermediates, and for Er2(SeO4)3 a phase transition was detected.

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