Acta Crystallographica Section B

Structural Science

Volume 60, Part 5 (October 2004)

Cover illustration: Crystal packing diagram of 1,4-benzoquinone with Hirshfeld surfaces. The translucent gray surfaces illustrate the nature of these novel surfaces and how they envelop each molecule and reflect the presence of neighbouring molecules. Colours mapped on the central surface represent the distance from the surface to the nearest nucleus in an adjacent molecule: red (shortest), through green, to blue (longest) (McKinnon, Spackman & Mitchell, Acta Cryst. B, in preparation).

• research papers

research papers

Acta Cryst. (2004). B60, 491-495  [ doi:10.1107/S0108768104011644 ] Reinvestigation of the structure of BaCuSi2O6 - evidence for a phase transition at high temperature K. M. Sparta and G. Roth Synopsis: Superstructure reflections have been observed in the room-temperature X-ray diffraction pattern of BaCuSi2O6. At 610 K the compound undergoes a structural phase transition upon which these superstructure reflections disappear. Online 15 September 2004

Acta Cryst. (2004). B60, 496-501  [ doi:10.1107/S0108768104017963 ] Geikielite-ecandrewsite solid solutions: synthesis and crystal structures of the Mg1-xZnxTiO3 (0 x 0.8) series R. P. Liferovich and R. H. Mitchell Synopsis: Crystal structure determination by Rietveld analysis of powder X-ray diffraction data shows that members of the geikielite-ecandrewsite solid-solution series Mg1-xZnxTiO3 (0 x 0.8) adopt the R ilmenite structure. Data are presented for cell dimensions, atomic coordinates and bond lengths together with volumes and distortion indices for all coordination polyhedra. Online 15 September 2004

Acta Cryst. (2004). B60, 502-511  [ doi:10.1107/S0108768104018051 ] Structures of three salts of phthalic acid; variation in crystal packing and geometry of the hydrogen phthalate ion A. Langkilde, D. Madsen and S. Larsen Synopsis: The crystal structures of salts of phthalic acid with MgO, diethylamine and 2,2'-dipyridylamine have been determined. An analysis is made of the two different hydrogen-bond patterns observed in the crystal structures of the hydrogen phthalate salts found in the Cambridge Structural Database. Online 15 September 2004

Acta Cryst. (2004). B60, 512-519  [ doi:10.1107/S0108768104016064 ] Water molecules insert into N-HCl-M hydrogen bonds while M-ClX-C halogen bonds remain intact in dihydrates of halopyridinium hexachloroplatinates F. Zordan and L. Brammer Synopsis: Crystals of the dihydrates of three halopyridinium hexachloroplatinate salts form networks that are propagated via N-HO and O-HCl-Pt hydrogen bonds and Pt-ClX-C halogen bonds. The water molecules can be considered to have been inserted into N-HCl-Pt hydrogen bonds anticipated in the anyhdrous form of such salts. Online 15 September 2004

Acta Cryst. (2004). B60, 520-527  [ doi:10.1107/S010876810401451X ] Strategies for the structure determination of endohedral fullerenes applied to the example of Ba@C74·Co(octaethylporphyrin)·2C6H6 K. Friese, M. Panthöfer, G. Wu and M. Jansen Synopsis: Strategies for the structure determination of endohedral fullerenes were applied to the example of Ba@C74·Co(OEP)·2C6H6. Online 15 September 2004

Acta Cryst. (2004). B60, 528-538  [ doi:10.1107/S0108768104015356 ] Structures of FeII spin-crossover complexes from synchrotron powder-diffraction data E. Dova, R. Peschar, M. Sakata, K. Kato, A. F. Stassen, H. Schenk and J. G. Haasnoot Synopsis: Using synchrotron powder-diffraction data and direct-space search techniques, crystal structures have been obtained at room temperature and 90 K for the compounds [Fe(teeX)6](BF4)2 (teeX is haloethyltetrazole, and X = I and Br), which both show a gradual, complete high-spin-to-low-spin transition according to molar magnetic susceptibility and 57Fe Mössbauer spectroscopy. Online 15 September 2004

Acta Cryst. (2004). B60, 539-546  [ doi:10.1107/S0108768104016611 ] Distribution of molecular centres in unit cells with respect to packing patterns E. Pidcock and W. D. S. Motherwell Synopsis: The position of the molecular centre in the unit cell in relation to the symmetry operators of a space group has been found to correlate with the packing pattern used to describe the crystal structure. Online 15 September 2004

Acta Cryst. (2004). B60, 547-558  [ doi:10.1107/S0108768104015113 ] Isostructurality in one and two dimensions: isostructurality of polymorphs L. Fábián and A. Kálmán Synopsis: An analysis of polymorphs retrieved from the Cambridge Structural Database shows that common one-, two- or three-dimensional molecular arrangements in the different forms can be identified for approximately half of the polymorphic systems investigated. Online 15 September 2004

Acta Cryst. (2004). B60, 559-568  [ doi:10.1107/S0108768104014557 ] Experimental electron density study of the supramolecular aggregation between 4,4'-dipyridyl-N,N'-dioxide and 1,4-diiodotetrafluorobenzene at 90 K R. Bianchi, A. Forni and T. Pilati Synopsis: The electron density of the complex of 4,4'-dipyridyl-N,N'-dioxide with 1,4-diiodotetrafluorobenzene has been determined by X-ray diffraction at 90 K and by accurate theoretical calculations. The topological properties of the IO halogen bond are reported and compared with those of the IN halogen bond obtained in a previous study. Online 15 September 2004

Acta Cryst. (2004). B60, 569-577  [ doi:10.1107/S0108768104014569 ] A crystallographic titration of the dipeptide L-isoleucyl-L-isoleucine C. H. Görbitz Synopsis: Crystal structure determinations are presented for L-isoleucyl-L-isoleucine in four different protonation states: as a zwitterion, a cation, an anion and a dimeric cation. Online 15 September 2004

Acta Cryst. (2004). B60, 578-588  [ doi:10.1107/S0108768104016532 ] Torsional vibration and central bond length of N-benzylideneanilines J. Harada, M. Harakawa and K. Ogawa Synopsis: Variable-temperature X-ray crystal structure analyses of N-benzylideneanilines revealed that the torsional vibration of the C-Ph and N-Ph bonds causes an apparent shortening of the C=N bond at room temperature. Online 15 September 2004

Acta Cryst. (2004). B60, 589-597  [ doi:10.1107/S0108768104016623 ] Conformational change of N-benzylideneanilines in crystals J. Harada, M. Harakawa and K. Ogawa Synopsis: Variable-temperature X-ray crystal structure analyses of several N-benzylideneanilines revealed that a conformational change through a pedal motion takes place in the crystals. Online 15 September 2004

Acta Cryst. (2004). B60, 598-608  [ doi:10.1107/S0108768104019846 ] Conformational analysis: crystallographic, molecular mechanics and quantum chemical studies of C-HO hydrogen bonding in the flexible bis(nosylate) derivative of catechol O. Q. Munro and L. Mariah Synopsis: The bis(nosylate) derivative of catechol, 2-{[(4-nitrophenoxy)sulfonyl]oxy}phenyl 4-nitrophenyl sulfate, exhibits an unusual extended solid-state structure (a one-dimensional hydrogen-bonded polymer) that is based on the formation of complementary intermolecular (aryl)C-HO(nitro) hydrogen-bond pairs. The molecular and `supramolecular' structure of this system has been further delineated using quantum chemical calculations (AM1 method) and molecular mechanics (MM+) simulations. Online 15 September 2004

Acta Cryst. (2004). B60, 609-620  [ doi:10.1107/S0108768104014466 ] X-ray diffraction and packing analysis on vintage crystals: Wilhelm Koerner's nitrobenzene derivatives from the School of Agricultural Sciences in Milano F. Demartin, G. Filippini, A. Gavezzotti and S. Rizzato Synopsis: The crystal structures of six nitrotoluene derivatives, synthesized by Wilhelm Koerner about a century ago and retrieved from a depository at the University of Milano, were determined. The crystal packings have been analyzed and lattice energies have been calculated by atom-atom potential methods and by the newly proposed Pixel method. Online 15 September 2004

Acta Cryst. (2004). B60, 621-625  [ doi:10.1107/S0108768104017380 ] Temperature dependence of the crystal structure of 3,5-di-tert-butylpyrazole from 10 K A. N. Sobolev and A. H. White Synopsis: The disordered crystal structure of 3,5-di-tert-butylpyrazole in its high-temperature phase has been described in terms of the superposition of two tautomeric forms. A phase transition at  110 K leads to the reorganization of the lattice to an ordered array of different conformers. Online 15 September 2004

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