Structural Science

 

Acta Cryst. (2003). B59, 429-438  [ doi:10.1107/S0108768103010450 ]

Structural characterization of YV₄O₈: simultaneous analysis of coexisting polytypes and simulation of diffuse scattering for a stacking disorder model

M. Onoda, A.-C. Dhaussy and Y. Kanke

Synopsis: Crystal structures of coexisting polytypes of YV₄O₈ were analyzed based on a commensurate composite crystal model, and domain structure was examined through diffuse streak simulation by the matrix method for one-directional disorder.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 439-448  [ doi:10.1107/S0108768103010474 ]

Influence of pressure on the lengths of chemical bonds

I. D. Brown, P. Klages and A. Skowron

Synopsis: Expressions are developed for the force constants and compressibilities of chemical bonds.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 449-455  [ doi:10.1107/S0108768103010346 ]

Structural characterization of the n = 5 layered perovskite neodymium titanate using high-resolution transmission electron microscopy and image reconstruction

M. Sayagués, K. Titmuss, R. Meyer, A. Kirkland, J. Sloan, J. Hutchison and R. Tilley

Synopsis: The refinement of the structure of Nd₅Ti₅O₁₇ from a restored high-resolution exit-plane wave is reported.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 456-462  [ doi:10.1107/S0108768103010851 ]

Mechanism of the morphotropic transformation between the rutile and corundum structural types

H. Katzke and R. Schlögl

Synopsis: A detailed structural mechanism which is based on crystallographic shear is proposed for the morphotropic transformation between the rutile and corundum structural types. The influence of randomly spaced and clustered CS planes on the X-ray diffraction patterns is calculated.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 463-471  [ doi:10.1107/S0108768103010073 ]

Ordered double perovskites - a group-theoretical analysis

C. J. Howard, B. J. Kennedy and P. M. Woodward

Synopsis: A rock-salt pattern of cation ordering in the ordered double perovskites A₂BB'X₆, combined with simple tilting of the octahedral units, leads to a number of distinct but closely related structures. There are 12 possible space groups listed, along with group-subgroup relationships and an indication of which transitions between the different structures are allowed to be continuous.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 472-478  [ doi:10.1107/S0108768103011194 ]

Structural trends and the electronic structure of the rare-earth oxomolybdates RMo₅O₈ (R = La, Ce, Pr, Nd, Sm, Eu and Gd) containing chains of bioctahedral Mo₁₀ clusters

P. Gougeon, P. Gall, J.-F. Halet and R. Gautier

Synopsis: The crystal structures of the rare-earth members of the series RMo₅O₈ (R = La to Gd) have been refined from single-crystal X-ray diffraction data. The evolution of the Mo-Mo distances with respect to the size and the charge of the cation as well as theoretical investigations are presented.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 479-486  [ doi:10.1107/S0108768103011200 ]

Towards direct correlations between spin-crossover and structural features in iron(II) complexes

M. Marchivie, P. Guionneau, J.-F. Létard and D. Chasseau

Synopsis: The crystal structure of [Fe(PM-BiA)₂(NCS)₂] form II is discussed, and compared with form I. Direct correlation between the structural and magnetic spin cross-over feature are drawn.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 487-491  [ doi:10.1107/S010876810301070X ]

1,2-Dimethyl-4-nitro-5-morpholinoimidazole and its hydrate: a case of a centrosymmetric-noncentrosymmetric ambiguity

M. Kubicki, T. Borowiak, G. Dutkiewicz, S. Sobiak and I. Weidlich

Synopsis: Crystals of the title compound and its hydrate are centrosymmetric. In the hydrate, homodromic arrays of hydrogen-bonded water molecules form a locally noncentrosymmetric structure. The disorder of these arrays over the two possible orientations creates an overall centrosymmetric structure.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 492-497  [ doi:10.1107/S0108768103010231 ]

Intermolecular -CH₃O₂N- contacts in two polymorphic modifications of (1E)-N'-[(E)-2-cyano-1-(dimethylamino)-2-nitrovinyl]-N,N-dimethylethanimidamide

V. A. Tafeenko, V. V. Chernyshev, A. V. Yatsenko, V. A. Makarov, E. J. Sonneveld, R. Peschar and H. Schenk

Synopsis: Structure and packing of (1E)-N'-[(E)-2-cyano-1-(dimethylamino)-2-nitrovinyl]-N,N-dimethylethanimidamide in two polimorphic phases are discussed.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 498-504  [ doi:10.1107/S0108768103012953 ]

Calculation of the crystal densities of molecular salts and hydrates using additive volumes for charged groups

S. Beaucamp, N. Marchet, D. Mathieu and V. Agafonov

Synopsis: A group contribution method to estimate crystal densities is extended to molecular salts, with applications in energetic materials.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 505-511  [ doi:10.1107/S0108768103011893 ]

Structure and degree of charge transfer of two polymorphs of a 1:1 molecular complex: [2,2'-bis-1,3-dithiole][9-dicyanomethylene-4,5,7-trinitrofluorene-2-carboxylic acid methyl ester] (TTF-MeDC2TNF)

A. Salmerón-Valverde, S. Bernès and J. G. Robles-Martínez

Synopsis: Two polymorphs of a TTF-based charge-transfer complex using 9-dicyanomethylene-4,5,7-trinitrofluorene-2-carboxylic acid methyl ester as an acceptor were synthesized and their crystal structures determined, revealing differences in crystal packing. The observed structural features are in agreement with IR data and correlate well with the calculated degree of charge transfer for each polymorph.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 512-526  [ doi:10.1107/S0108768103011510 ]

Halogen-bond geometry: a crystallographic database investigation of dihalogen complexes

C. Ouvrard, J.-Y. Le Questel, M. Berthelot and C. Laurence

Synopsis: Linear and directional Y-XB halogen bonds are found; their distances depend on the Lewis acidity of YX and the Lewis basicity of B.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 527-536  [ doi:10.1107/S0108768103011297 ]

Structural phases of hexamethylenetetramine-pimelic acid (1/1): a unified description based on a stacking model

M. Gardon, C. B. Pinheiro and G. Chapuis

Synopsis: The structures of the 1:1 adduct of hexamethylenetetramine and pimelic acid are investigated. A model based on a stacking sequence of an elementary layer is proposed for describing the different structures in a unified scheme. The main features observed on diffraction patterns are reproduced by simulation using the model.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 537-538  [ doi:10.1107/S0108768103009467 ]

Anti-wurtzite reoriented

M. Hostettler and H. D. Flack

Synopsis: Anti-wurtzite and wurtzite are the same crystal structure.

Online 25 July 2003

 

Acta Cryst. (2003). B59, 539  [ doi:10.1107/S0108768103010747 ]

Disordered Materials

Online 25 July 2003

 

Acta Cryst. (2003). B59, 539  [ doi:10.1107/S0108768103016082 ]

Linus Pauling selected scientific papers

Online 25 July 2003