Acta Crystallographica Section B

Structural Science

Volume 61, Part 5 (October 2005)

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].

• research papers

research papers

Acta Cryst. (2005). B61, 473-480  [ doi:10.1107/S0108768105022536 ] Diffuse scattering and ordering in the short-range modulated paraelectric phase of sodium nitrite, NaNO2 K. Lukaszewicz, A. Pietraszko and M. Kucharska Synopsis: Contrary to the well known modulated structures with sharp satellite reflections, the diffraction pattern of a short-range modulated structure contains diffuse satellite reflections. The crystal structure of NaNO2 above TN = 437.7 K in the paraelectric phase is short-range modulated with remnants of distorted fragments of a sinusoidal modulation. Online 23 September 2005

Acta Cryst. (2005). B61, 481-485  [ doi:10.1107/S0108768105017362 ] Evidence for differentiation in the iron-helicoidal chain in GdFe3(BO3)4 S. A. Klimin, D. Fausti, A. Meetsma, L. N. Bezmaternykh, P. H. M. van Loosdrecht and T. T. M. Palstra Synopsis: The structure phase transition of GdFe(BO) is investigated. A single-crystal X-ray structure study is reported at room temperature and at T = 90 K. The low-temperature space group found is P3121. Online 23 September 2005

Acta Cryst. (2005). B61, 486-491  [ doi:10.1107/S0108768105022585 ] Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on [001] silicon A. Alberti, C. Bongiorno, B. Cafra, G. Mannino, E. Rimini, T. Metzger, C. Mocuta, T. Kammler and T. Feudel Synopsis: In this work we show that in a 14 nm-thick NiSi layer, the silicide lattice can three-dimensionally adapt to that of a [001]-oriented Si substrate by forming transrotational domains. The resulting structural properties are promising to improve the structural and electrical stability of very thin NiSi layers. Online 23 September 2005

Acta Cryst. (2005). B61, 492-497  [ doi:10.1107/S0108768105017714 ] Extremely long period-stacking structure in the Sb-Te binary system K. Kifune, Y. Kubota, T. Matsunaga and N. Yamada Synopsis: The crystal structures of Sb-Te compounds that are materials currently used for DVDs were investigated by powder X-ray diffraction using synchrotron radiation. Each structure is fundamentally a simple stacking structure, but the stacking period changes regularly with composition and becomes extremely long. Online 23 September 2005

Acta Cryst. (2005). B61, 498-503  [ doi:10.1107/S0108768105025085 ] Reversible pressure-induced structure changes in turbostratic BN-C solid solutions V. L. Solozhenko and O. O. Kurakevych Synopsis: The crystallographic mechanism of the pressure-induced transformation of turbostratic graphite-like BN-C solid solutions at room temperature has been studied by Rietveld analysis and numerical modeling. Online 23 September 2005

Acta Cryst. (2005). B61, 504-510  [ doi:10.1107/S0108768105020021 ] Searching the Cambridge Structural Database for polymorphs J. van de Streek and S. Motherwell Synopsis: An automated method to scan a total of over 325 000 small-molecule crystal structures in the Cambridge Structural Database for polymorphs is described. The results for 35 000 pairs of crystal structures are reported: 308 previously unknown individual polymorphs were identified. Online 23 September 2005

Acta Cryst. (2005). B61, 511-527  [ doi:10.1107/S0108768105016563 ] A third blind test of crystal structure prediction G. M. Day, W. D. S. Motherwell, H. L. Ammon, S. X. M. Boerrigter, R. G. Della Valle, E. Venuti, A. Dzyabchenko, J. D. Dunitz, B. Schweizer, B. P. van Eijck, P. Erk, J. C. Facelli, V. E. Bazterra, M. B. Ferraro, D. W. M. Hofmann, F. J. J. Leusen, C. Liang, C. C. Pantelides, P. G. Karamertzanis, S. L. Price, T. C. Lewis, H. Nowell, A. Torrisi, H. A. Scheraga, Y. A. Arnautova, M. U. Schmidt and P. Verwer Synopsis: The findings of the third blind test of crystal structure prediction are presented and discussed in the context of the previous collaborations - CSP1999 and CSP2001. Online 23 September 2005

Acta Cryst. (2005). B61, 528-535  [ doi:10.1107/S010876810502611X ] Comparing hypothetical structures generated in the third Cambridge blind test of crystal structure prediction B. P. van Eijck Synopsis: Extended lists of the hypothetical crystal structures of two small semi-rigid molecules, submitted in the third Cambridge blind test of crystal structure prediction, were analyzed for completeness and correlation between energies. Online 23 September 2005

Acta Cryst. (2005). B61, 536-547  [ doi:10.1107/S0108768105023189 ] Morphotropism: link between the isostructurality, polymorphism and (stereo)isomerism of organic crystals A. Kálmán Synopsis: Morphotropism (i.e. the non-crystallographic rotation of motifs) bridges the phenomena of isostructurality, polymorphism and (stereo)isomerism. Various forms of virtual and effective rotation of the common motifs, through either 90 or 180°, between chemically related structures, are presented. Online 23 September 2005

Acta Cryst. (2005). B61, 548-557  [ doi:10.1107/S0108768105020331 ] Representing structural databases in a self-organizing map R. Wehrens, W. Melssen, L. Buydens and R. de Gelder Synopsis: A visualization of diversity in structural databases by mapping powder diffraction patterns in a two-dimensional self-organizing map is presented, including principles and applications. Online 23 September 2005

Acta Cryst. (2005). B61, 558-568  [ doi:10.1107/S0108768105018549 ] Validation of a search technique for crystal structure prediction of flexible molecules by application to piracetam H. Nowell and S. L. Price Synopsis: A new approach to the crystal structure prediction of flexible molecules is described and illustrated using a `blind' prediction of a recently solved conformational polymorph of piracetam. Online 23 September 2005

Acta Cryst. (2005). B61, 569-576  [ doi:10.1107/S0108768105021312 ] A structural study of new potent and selective antagonists to the A2B adenosine receptor V. Ferretti, L. Pretto, M. A. Tabrizi and V. Bertolasi Synopsis: The crystal structures of five new xanthinic derivatives acting as adenosine antagonists have been determined. Other molecules of known biological activity have been reported and compared, with the aim of understanding the structural features controlling their affinity capabilities and selectivity. Online 23 September 2005

Acta Cryst. (2005). B61, 577-584  [ doi:10.1107/S0108768105022792 ] Energetic materials: -NTO crystallizes as a four-component triclinic twin N. Bolotina, K. Kirschbaum and A. A. Pinkerton Synopsis: The -polymorph of the energetic material 5-nitro-2,4-dihydro-1,2,4,-triazol-3-one (NTO) crystallizes as a four-component triclinic twin (fourling). The twin laws are rationalized on the basis of the symmetry of a pseudo-orthorhombic superstructure and the molecular packing. Online 23 September 2005

Acta Cryst. (2005). B61, 585-594  [ doi:10.1107/S0108768105023931 ] Bayesian methods for the conformational classification of eight-membered rings J. Pérez, K. Nolsøe, M. Kessler, L. García, E. Pérez and J. L. Serrano Synopsis: A probabilistic model is used to group the eight-membered ring conformations using the intra-ring torsion angles. Hints about the interconversion pathways between conformations are also obtained. Online 23 September 2005

Acta Cryst. (2005). B61, 595-600  [ doi:10.1107/S0108768105017374 ] In situ high-pressure crystallization and compression of halogen contacts in dichloromethane M. Podsiadlo, K. Dziubek and A. Katrusiak Synopsis: The pressure-frozen structure of CH2Cl2 has been determined by single-crystal X-ray diffraction at 1.33 and 1.63 GPa, and the intermolecular electrostatic, halogenhalogen and Hhalogen crystal cohesion forces have been analysed. Online 23 September 2005

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