Structural Science

 

Acta Cryst. (2012). B68, 323-340  [ doi:10.1107/S0108768112017478 ]

Structure refinement and superspace description of the system Bi_2(n + 2)Mo_nO_6(n + 1) (n = 3, 4, 5 and 6)

P. J. Bereciartua, F. J. Zuñiga, J. M. Perez-Mato, V. Petrícek, E. Vila, A. Castro, J. Rodríguez-Carvajal and S. Doyle

Synopsis: The system of flexible composition Bi_2(n + 2)Mo_nO_6(n + 1) is described within the superspace formalism with two models, depending on the parity of the parameter n.

B-IncStrDB reference: 6402ESgKUu

Online 28 June 2012

 

Acta Cryst. (2012). B68, 341-355  [ doi:10.1107/S0108768112018095 ]

Unified (3 + 1)-dimensional superspace description of the 2212-type stair-like [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] family of compounds

L. Elcoro, O. Pérez, J. M. Perez-Mato and V. Petrícek

Synopsis: Two commensurate members (m = 4, 5) of the 2212 stair-like family of compounds with the composition [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] have been analyzed and refined in the (3 + 1)-dimensional superspace framework. Both compounds are described by a unique model, including displacive modulations. The assumption of the validity of the proposed model for a range of compositions allows a realistic prediction of the structures of other members of the family.

B-IncStrDB reference: 6372EfECT1

Online 28 June 2012

 

Acta Cryst. (2012). B68, 356-363  [ doi:10.1107/S0108768112027462 ]

The natural tiling approach to cation conductivity in KAlO₂ polymorphs

V. I. Voronin, G. S. Shekhtman and V. A. Blatov

Synopsis: A detailed analysis of correlations between structural features and cation conductivity is performed for KAlO₂ polymorphs in a wide temperature range of 300-1023 K. To explore the migration maps of K⁺ cations we have used neutron diffraction data and applied for the first time a novel algorithm based on the natural tiling concept and implemented it into the program package TOPOS.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 364-377  [ doi:10.1107/S0108768112021234 ]

On the charge transfer between conventional cations: the structures of ternary oxides and chalcogenides of alkali metals

A. Vegas

Synopsis: The structure of ternary oxides and chalcogenides of alkali metals can be better understood by assuming the electron transfer between cations, in an extension of the Zintl-Klemm concept.

Online 28 June 2012

    

Acta Cryst. (2012). B68, 378-388  [ doi:10.1107/S0108768112030091 ]

Crystallographic input data for (001)-, (110)- and (111)-oriented superlattices

Z. Touaa and N. Sekkal

Synopsis: The necessary crystallographic input data are given for electronic-structure calculations of supercells with the (111), (001) or (110) orientations. They are applied to calculations on GaAs/AlAs superlattices of different thicknesses.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 389-400  [ doi:10.1107/S0108768112018319 ]

[Ni(MeCN)(H₂O)₂(NO₃)₂]·(15-crown-5)·MeCN: detailed study of a four-phase sequence that includes an intermediate modulated phase

M. A. Siegler, S. Parkin and C. P. Brock

Synopsis: Acetonitrilediaqua-¹O-nitrato-²O-nitratonickel(II) 15-crown-5 acetonitrile solvate was studied by single-crystal X-ray diffraction at intervals of 10 K in the range 90-273 K as the crystal passed, without obvious damage, through three phase transitions. The phase sequence includes an intermediate modulated phase that seems to be a kind of striped hybrid of the phases stable at immediately higher and lower temperatures.

Online 28 June 2012

 

Acta Cryst. (2012). B68, 401-406  [ doi:10.1107/S0108768112030212 ]

Synthesis, structure and spectroscopic properties of a novel compound bis(benzylamino)silver(I) benzylcarbamate

J. Liu, X. Zeng and H. Li

Synopsis: Bis(benzylamino)silver(I) benzylcarbamate contains silver atoms coordinated to two nitrogen atoms of amino groups from different benzylamine molecules; metal-oxygen interactions are absent in the crystal structure. The title compound exhibits fluorescence properties.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 407-411  [ doi:10.1107/S0108768112019994 ]

Structure determination of L-arabinitol by powder X-ray diffraction

P. Derollez, Y. Guinet, F. Affouard, F. Danède, L. Carpentier and A. Hédoux

Synopsis: The crystal structure of L-arabinitol at room temperature was solved from its powder X-ray diffraction pattern. The starting structural model was found by the simulated annealing method. The structure was obtained through Rietveld refinements with soft restraints on the interatomic bond lengths and bond angles. The H atoms of hydroxyl groups were localized by a minimization of the crystalline energy.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 412-423  [ doi:10.1107/S0108768112028972 ]

X-ray diffraction and Raman study of DL-alanine at high pressure: revision of phase transitions

N. A. Tumanov and E. V. Boldyreva

Synopsis: Structural changes in DL-alanine at pressures up to 8.3 GPa are not related to phase transitions.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 424-430  [ doi:10.1107/S0108768112027450 ]

A time-resolved powder diffraction study of in-situ photodimerization kinetics of 9-methylanthracene using a CCD area detector and parametric Rietveld refinement

A. F. Mabied, M. Müller, R. E. Dinnebier, S. Nozawa, M. Hoshino, A. Tomita, T. Sato and S. Adachi

Synopsis: The kinetics of the 9-methylanthracene photodimerization reaction was examined by time-resolved powder diffraction using a CCD detector and parametric Rietveld refinement.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 431-443  [ doi:10.1107/S010876811202561X ]

Cocrystals of 5-fluorocytosine. I. Coformers with fixed hydrogen-bonding sites

M. Tutughamiarso, G. Wagner and E. Egert

Synopsis: Cocrystallization attempts with 5-fluorocytosine yielded eight cocrystals and two structures of a single compound. In six cocrystals, the expected heterodimers held together by two or three hydrogen bonds are present. Ab initio energy calculations helped to rationalize the intermolecular hydrogen-bonding patterns observed in the crystal structures.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 444-452  [ doi:10.1107/S0108768112029977 ]

Cocrystals of 5-fluorocytosine. II. Coformers with variable hydrogen-bonding sites

M. Tutughamiarso and E. Egert

Synopsis: Five cocrystals (four with 5-fluorocytosine and one with 6-aminoisocytosine) are presented to study the influence of complementary binding on conformational flexibility and the tautomeric equilibrium.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 453-464  [ doi:10.1107/S0108768112026456 ]

42 salt forms of tyramine: structural comparison and the occurrence of hydrate formation

N. E. B. Briggs, A. R. Kennedy and C. A. Morrison

Synopsis: A structural study of 42 salt forms of the phenylethylamine tyramine examines cation conformation, cation packing and hydrogen bonding as well as showing that hydrate formation is favoured both by higher total numbers of potential hydrogen-bond acceptors and donors and by lower donor:acceptor ratios.

Online 17 July 2012

 

Acta Cryst. (2012). B68, 465  [ doi:10.1107/S010876811203193X ]

Pressure-induced phase transitions in L-alanine, revisited. Corrigendum

N. A. Tumanov, E. V. Boldyreva, B. A. Kolesov, A. V. Kurnosov and R. Quesada Cabrera

Synopsis: Corrigendum to the data published in the article by Tumanov et al. [(2010), Acta Cryst. B66, 458-471].

Online 17 July 2012