Acta Crystallographica Section B

Structural Science, Crystal Engineering and Materials

Volume 69, Part 1 (February 2013)

Cover illustration: Reduction of volumes of the voids in the crystal structures of DL-alanine and L-alanine on application of 6 GPa of pressure. Yellow voids are shown within the ball-and-stick structure models. The molecules as well as the topologies and symmetries of their packings are preserved over the whole pressure range of 0-6 GPa. See Fig. 4 in Tumanov & Boldyreva [(2012), Acta Cryst. B68, 412-423].

• lead articles
• research papers
• short communications

lead articles

Acta Cryst. (2013). B69, 1-16  [ doi:10.1107/S2052519212051366 ] The charge-flipping algorithm in crystallography L. Palatinus Synopsis: The state-of-the-art charge-flipping algorithm is summarized, and its applications to various crystallographic problems connected with structure solution are reviewed. Online 19 January 2013

research papers

Acta Cryst. (2013). B69, 17-29  [ doi:10.1107/S205251921205110X ] The role of the coordination defect (CD) in the structures of anion-deficient, fluorite-related compounds D. J. M. Bevan, L. L. Martin and R. L. Martin Synopsis: The many superstructure phases of rare-earth oxides MnO2n - 2 are rationalized in terms of the `coordination defect model'. Online 19 January 2013

Acta Cryst. (2013). B69, 30-35  [ doi:10.1107/S2052519213000183 ] Structural transformations in the low-temperature grown GaAs with superlattices of Sb and P -layers M. V. Baidakova, N. A. Bert, V. V. Chaldyshev, V. N. Nevedomsky, M. A. Yagovkina, V. V. Preobrazhenskii, M. A. Putyato and B. R. Semyagin Synopsis: Structural transformations in superlattices of Sb and P -layers upon annealing were studied in low-temperature grown GaAs. The combination of Sb and P -layers appears to be an effective tool for spatial patterning of arsenic nanoinclusions and prevention of the defect formation in the GaAs matrix. Online 19 January 2013

Acta Cryst. (2013). B69, 36-42  [ doi:10.1107/S2052519212046738 ] Electronic influence of -diketonato-type ligands on the coordination of 1,5-cyclooctadiene to palladium(II) as defined by `Venus fly trap' geometric parameters T. N. Hill, A. Roodt and G. Steyl Synopsis: The influence of inter- and intramolecular interactions in a range of palladium(II) -diketonato complexes, as investigated by single-crystal X-ray crystallography, is presented in relation to solid-state packing modes, bond distances, hydrogen bonds and halogen interactions, while the `Venus fly trap' parameters of the 1,5-cyclooctadiene ligand are defined as a function of its bonding to the palladium(II) metal centre. Online 20 December 2012

Acta Cryst. (2013). B69, 43-54  [ doi:10.1107/S2052519212050439 ] Weak intermolecular hydrogen and halogen interactions in an isomorphous halogen series of pseudoterpyridine ZnII complexes F. Dumitru, Y.-M. Legrand, M. Barboiu and A. van der Lee Synopsis: The structures of four halogen pseudoterpyridine ZnII complexes are analysed for the influence of very weak intermolecular interactions on their crystal packings. Online 19 January 2013

Acta Cryst. (2013). B69, 55-61  [ doi:10.1107/S2052519212048336 ] Structural and electronic aspects of hydrogen bonding in two polymorphs of butylene-N,N'-bis(O,O'-diarylphosphoramidate) K. Gholivand, A. A. E. Valmoozi and H. R. Mahzouni Synopsis: The solid-state and gas-phase structure of (C6H5O)2P(O)NH(CH2)4NHP(O)(OC6H5)2 are reported. Online 20 December 2012

Acta Cryst. (2013). B69, 62-69  [ doi:10.1107/S2052519212047410 ] Entry point into new trimeric and tetrameric imide-based macrocyclic esters derived from isophthaloyl dichloride and methyl 6-aminonicotinate P. Mocilac and J. F. Gallagher Synopsis: The reaction of isophthaloyl dichloride with methyl 6-aminonicotinate yields `3 + 3' and `4 + 4' imide-linked macrocycles with the former representing a new macrocycle class (trezimide). The role of 2-aminopyridine in imide hinge formation and ultimately macrocyclization is pivotal to this one-step synthetic route into cyclic triimides (trezimides) and tetraimides (tennimides). Online 20 December 2012

Acta Cryst. (2013). B69, 70-76  [ doi:10.1107/S2052519212049329 ] Thermodynamic and structural relationships between the two polymorphs of 1,3-dimethylurea C. Näther, C. Döring, I. Jess, P. G. Jones and C. Taouss Synopsis: Polymorph (I) of dimethylurea (Fdd2) is the more stable modification at room temperature, where polymorph (II) (P21212) is metastable; the thermodynamic transition temperature lies between 253 K and room temperature. Online 20 December 2012

Acta Cryst. (2013). B69, 77-85  [ doi:10.1107/S2052519212051147 ] A high-pressure polymorph of chlorpropamide formed on hydrostatic compression of the -form in saturated ethanol solution Y. V. Seryotkin, T. N. Drebushchak and E. V. Boldyreva Synopsis: The crystal structure of a high-pressure monoclinic polymorph (P2111) of chlorpropamide has been determined. It is formed at  2.8 GPa on hydrostatic compression of the orthorhombic stable -polymorph (P212121) in saturated ethanol solution. Online 19 January 2013

short communications

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