Acta Crystallographica Section B

Structural Science

Volume 67, Part 3 (June 2011)

Cover illustration: The cover picture highlights an artefact in the electrostatic potential of the macrolide antibiotic roxithromycin as derived via multipole refinement of X-ray diffraction data.  Ignoring the hydrogen disorder (left) in the oxime chain leads to a falsely positive electrostatic potential there as a result of the multipole model's being flexible enough to fit the averaged electron density.  If the invariom formalism, which uses theoretical electron density, is applied to the disordered region (right) the artefact disappears.  A procedure for obtaining reliable electron density distributions in the presence of disorder has been proposed [Holstein et al. (2010). Acta Cryst. B66, 568-577].

• research papers
• short communications
• obituaries

research papers

Acta Cryst. (2011). B67, 193-204  [ doi:10.1107/S0108768111005179 ] Determination of the local structure of a cage with an oxygen ion in Ca12Al14O33 T. Sakakura, K. Tanaka, Y. Takenaka, S. Matsuishi, H. Hosono and S. Kishimoto Synopsis: The crystal structure of mayenite (12CaO·7Al2O3) was determined including the local structure of the cage deformed by an O ion clathrated in two out of 12 cages. Online 13 April 2011

Acta Cryst. (2011). B67, 205-217  [ doi:10.1107/S0108768111013814 ] Modulated anharmonic ADPs are intrinsic to aperiodic crystals: a case study on incommensurate Rb2ZnCl4 L. Li, A. Wölfel, A. Schönleber, S. Mondal, A. M. M. Schreurs, L. M. J. Kroon-Batenburg and S. van Smaalen Synopsis: The superspace maximum entropy method (MEM) density in combination with structure refinements has been used to uncover the modulation in incommensurate Rb2ZnCl4 close to the lock-in transition. Modulated atomic displacement parameters (ADPs) and modulated anharmonic ADPs are found to form an intrinsic part of the modulation. Refined values for the displacement modulation function depend on the presence or absence of modulated ADPs in the model. Online 14 May 2011

Acta Cryst. (2011). B67, 218-225  [ doi:10.1107/S0108768111014534 ] Structure analysis of titanate nanorods by automated electron diffraction tomography I. Andrusenko, E. Mugnaioli, T. E. Gorelik, D. Koll, M. Panthöfer, W. Tremel and U. Kolb Synopsis: A hitherto unknown phase of sodium titanate, NaTi3O6(OH)·2H2O, was identified as the intermediate species in the synthesis of TiO2 nanorods. This new phase, prepared as nanorods, was investigated by X-ray powder diffraction, thermogravimetry and high-resolution electron transmission microscopy. The structure was finally solved ab initio by electron diffraction data collected through automated diffraction tomography. Online 14 May 2011

Acta Cryst. (2011). B67, 226-237  [ doi:10.1107/S0108768111009657 ] The effect of pressure on the crystal structure of bianthrone R. D. L. Johnstone, D. Allan, A. Lennie, E. Pidcock, R. Valiente, F. Rodríguez, J. Gonzalez, J. Warren and S. Parsons Synopsis: Piezochromism in bianthrone is investigated using a combination of high-pressure single-crystal and powder diffraction, UV-vis spectroscopy and periodic density functional theory calculations. Online 13 April 2011

Acta Cryst. (2011). B67, 238-243  [ doi:10.1107/S0108768111010470 ] Solid-state and gas-phase structures of two conformers of N-(4-methylphenyl)-N',N''-bis(morpholinyl) phosphoric triamide; insights from X-ray crystallography and DFT calculations K. Gholivand and H. R. Mahzouni Synopsis: The structural and electronic aspects, in correlation with the hydrogen bonding, of two conformers of N-(4-methylphenyl)-N',N''-bis(morpholinyl) phosphoric triamide have been studied by X-ray crystallography and DFT calculations. Online 13 April 2011

Acta Cryst. (2011). B67, 244-249  [ doi:10.1107/S0108768111015801 ] Intermolecular interactions and charge transfer in the 2:1 tetrathiafulvalene bromanil complex, (TTF)2-BA P. García-Orduña, S. Dahaoui and C. Lecomte Synopsis: The structure of the 2:1 charge-transfer complex of tetrathiafulvalene and bromanil, (C6H4S4)2-C6Br4O2, was determined at 293, 100 and 25 K. Orthogonal trimers are the building blocks of the crystal packing. Online 14 May 2011

Acta Cryst. (2011). B67, 250-262  [ doi:10.1107/S0108768111013140 ] Charge-density analysis of 1-nitroindoline: refinement quality using free R factors and restraints B. Zarychta, J. Zaleski, J. Kyziol, Z. Daszkiewicz and C. Jelsch Synopsis: Precise analysis of the charge-density distribution of 1-nitroindoline using R-free refinement for an optimal restraints scheme. Online 14 May 2011

short communications

Acta Cryst. (2011). B67, 263-265  [ doi:10.1107/S0108768111010408 ] A simplified empirical model for approximation of the `bond valence-bond length' correlation for H-O bonds V. Sidey Synopsis: The `bond valence (s)-bond length (r)' correlation reported earlier for H-O bonds has been closely approximated using the function s = ( - r)1/, where = 1.185 (10), = 0.321 (8) and = 0.36. Online 13 April 2011

obituaries

Acta Cryst. (2011). B67, 266-267  [ doi:10.1107/S0108768111017599 ] Frank H. Herbstein (1926-2011) M. Kaftory Synopsis: Obituary for Frank H. Herbstein Online 14 May 2011

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