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Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

October 2009 issue

Highlighted illustration

Cover illustration: Though cyclohexanol is a simple compound it has a rich phase diversity at low temperature. It forms a disordered glassy phase on cooling, but this can be transformed into ordered phases (II), (III) and the metastable (III'), which all have different hydrogen-bonding motifs.  The series of transitions is attributable to the conformational flexibility of the hydroxyl group [Ibberson et  al. (2008). Acta Cryst. B64, 573-582].

research papers




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It is shown that there is a close relationship between the modulation of the atomic positions and the modulation of the magnetic moments of Mn ions in CaCuxMn7−xO12 compounds for x = 0 and x = 0.1 at low temperatures.

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Wavefunctions with up to third-order harmonics were refined in order to describe the positional modulation of incommensurate low tridymite. The structural modulation is accompanied by an additional modulation of the anisotropic displacement parameters.

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Caesium disulfate represents a new structure type with a uniquely high number of independent formula units at 120 K. Between 230 and 250 K it shows an order–disorder transition. The Cs+-ion arrangement shows a remarkable similarity to the high-pressure RbIV metal structure.

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Solid solutions of La2TiO5 and La4Ga2O9 were structurally characterized by X-ray powder diffraction. The structural relationship between end members – orthorhombic La2TiO5 and monoclinic La4Ga2O9 – was elucidated.

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A new Eu-SiAlON crystal, Eu3Si15 − xAl1 + xOxN23 − x (x ≃ 5/3), was grown. Its structure is considered to be that of a commensurate composite crystal. A structure model in (3 + 1)-dimensional superspace is also proposed.

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Ternary fluorides BaMF4 (M = Zn, Mg, Mn) have been studied in the temperature range from 300 to 10 K.

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The modulated structure of Sr10Ga6O19 at ambient temperature has been investigated. At high temperature, two phase transitions (one between 453 and 503 K and the other between 503 and 673 K) have been found.

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The sub-bromide Bi7 − δNi2Br5 − 2δ contains Bi3Ni rods, which are isolated by a bromido-bismuthate matrix. A structure model is developed in (3 + 1)-dimensional superspace.

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Topological analyses of the experimental electron-density distributions in crystals of five chain polymers [M(μ-X)2(py)2] (M = Zn, Cd; X = Cl, Br; py = 3,5-substituted pyridine) confirmed the existence of (3, −1) critical points both for intuitively strong chemical bonds and for secondary interactions. The latter comprise intra- and inter-strand C—H⋯XM hydrogen bonds and C—XX—C interhalogen contacts and stabilize the polymeric structures unusual for Zn as the metal center.


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Structure analysis of GS (ground state) and two light-induced (SI and SII) metastable linkage NO isomers of [Ru(py)4Cl(NO)](PF6)2·0.5H2O is presented. The experimental results are compared with solid-state calculations based on density functional theory (DFT). The influence of the different occupancies of the metastable isomer SI and GS on the refinement results was solved by a simulation procedure.

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The maximum-entropy charge densities of six amino acids and peptides reveal systematic dependencies of the properties at bond critical points on bond lengths. MEM densities demonstrate that low-order multipoles (lmax = 1) and isotropic atomic displacement parameters for H atoms in the multipole model are insufficient for capturing all the features of charge densities in hydrogen bonds.

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The crystalline structure of ethyl 1′,2′,3′,4′,4a′,5′,6′,7′-octahydrodispiro[cyclohexane-1,2′-quinazoline-4′,1′′-cyclohexane]-8′-carbodithioate, C21H34N2S2, a bidentate pro-ligand with a coordination sphere of the type [NS]1−, was solved and refined from synchrotron powder diffraction data, and compared with in-vacuum density-functional theory (DFT) B3LYP/6-311G* and solid-state density-functional tight-binding (DFTB) theoretical calculations.

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Quantum-topological analysis of electron density and density-based functions is used to reveal the role of the Lewis-type molecular complementarity, the electrostatic force field and the features of the exchange and correlation energy density in forming the observed three-dimensional structure of the α-N2O4 crystal.
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