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Cover illustration: The arrangements of boxes shown represent the possible packing patterns of four molecules (each with dimensions L, M and S) in a unit cell, as described by the Box Model of crystal packing [Pidcock & Motherwell (2004). Cryst. Growth Des., 4, 611-620]. Application of this model to experimental P21/c structures revealed that the lower surface area packing patterns, for example 221L and 221M, are populated to a much greater extent than the higher surface area packing patterns of 114M and 114L. This finding indicates molecular shape is of primary importance in crystal packing [Pidcock & Motherwell (2004), Acta Cryst. B60, 539-546; Pidcock & Motherwell (2004), Acta Cryst. B60, 725-733]. |
Acta Cryst. (2005). B61, 361-366 [ doi:10.1107/S0108768105016393 ]
Synopsis: Using the superspace approach allowed a plausible model for the commensurate modulated structure of KNbOB2O5 to be determined, which was then refined as a superstructure.
Online 19 July 2005
Acta Cryst. (2005). B61, 367-380 [ doi:10.1107/S0108768105013455 ]
Synopsis: The crystal structure of CaCuGe2O6, which is closely related to the clinopyroxene structure type, was studied between 15 and 800 K to elucidate the temperature-dependent variation of structural parameters. A phase transition from P21/c to C2/c was found at 650 K.
Online 19 July 2005
Acta Cryst. (2005). B61, 381-386 [ doi:10.1107/S0108768105013480 ]
Synopsis: The crystal structure of Sr(OH)2·8H2O has been determined at 20, 100 and 200 K from neutron diffraction data. The structure consists of double layers of H2O and OH- ions separated by Sr2+ along the c axis.
Online 19 July 2005
Acta Cryst. (2005). B61, 387-399 [ doi:10.1107/S0108768105015521 ]
Synopsis: Simulations of electron diffraction patterns have been performed for each of the known perovskite tilt systems. Full details of the allowed reflections for each system are presented along with examples showing how simple selected-area diffraction patterns can be used to identify tilt systems.
Online 19 July 2005
Acta Cryst. (2005). B61, 400-406 [ doi:10.1107/S010876810501726X ]
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-K5Yb(MoO4)4 as an exampleSynopsis: The complementary character of the first and second coordination-sphere interactions is illustrated with the incommensurately modulated structure -K5Yb(MoO4)4. It is also shown that even the third coordination sphere should not be neglected in the studies of modulated structures.
Online 19 July 2005
Acta Cryst. (2005). B61, 407-417 [ doi:10.1107/S0108768105015211 ]
Synopsis: Pseudo-symmetry operations were used to identify the major and minor components of the reflection intensities. This suggested constraints and restraints to optimize the refinement pathway by minimizing the noise in the minor components, and allowed the successful refinement of the near 1:1 twinned pseudo-symmetric crystal of the title compound.
Online 19 July 2005
Acta Cryst. (2005). B61, 418-428 [ doi:10.1107/S0108768105014114 ]
Synopsis: A topological analysis of the experimental electron density in racemic ethylenebis(1-indenyl)zirconium dichloride has been performed. All the atomic interactions and a charge transfer from the Zr atom to the ligands were quantitatively characterized and the `ligand-opposed' charge concentrations around Zr were revealed using the Laplacian of the electron density and a one-particle potential.
Online 19 July 2005
Acta Cryst. (2005). B61, 429-434 [ doi:10.1107/S0108768105016083 ]
Synopsis: Lanthanide-nitrogen bond-valence parameters are presented as they have been calculated for coordination compounds.
Online 19 July 2005
Acta Cryst. (2005). B61, 435-442 [ doi:10.1107/S0108768105015004 ]
Synopsis: The crystal structure of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine was solved and refined from X-ray powder diffraction data by applying the derivative difference minimization (DDM) method. All the atomic positions, including those of the H atoms, were located and refined without restraints. The reproducibility and precision of the results obtained by DDM and Rietveld methods are compared.
Online 19 July 2005
Acta Cryst. (2005). B61, 443-448 [ doi:10.1107/S010876810501637X ]
Synopsis: The electron density distribution of morphine hydrate has been derived from high-resolution single-crystal X-ray diffractions measurements at 25 K and was compared with the theoretical calculated fragment molecules from which the morphine molecule can be reconstructed.
Online 19 July 2005
Acta Cryst. (2005). B61, 449-454 [ doi:10.1107/S0108768105019191 ]
Synopsis: The low-temperature and high-pressure crystal structures of cyclobutanol have been determined using single-crystal X-ray diffraction techniques. At temperatures below 493 K, cyclobutanol crystallizes in the Aba2 space group (Z' = 2) and its crystal structure is composed of pseudo-threefold hydrogen-bonded molecular catemers. At a pressure of 1.3 GPa, the crystal symmetry changes to Pna21 (Z' =1) and the molecular catemers adopt a pseudo-twofold arrangement.
Online 19 July 2005
Acta Cryst. (2005). B61, 455-463 [ doi:10.1107/S0108768105017064 ]
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/ mixed lactose by X-ray powder diffractionSynopsis: The stoichiometry of 1/1 / mixed lactose was determined by NMR. Its structure was solved by X-ray powder diffraction and from the minimization of the crystalline energy. The simulated annealing method, followed by Rietveld refinements with soft constraints on bond lengths and angles was used.
Online 19 July 2005
Acta Cryst. (2005). B61, 464-472 [ doi:10.1107/S0108768105017258 ]
Synopsis: Barbituric acid dihydrate undergoes a reversible orthorhombic-to-monoclinic phase transition when cooled below 200 K. This second phase is stable down to 100 K. There are clear differences in the crystal packing of the two phases, although the hydrogen-bonding motifs do not change.
Online 19 July 2005
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