Structural Science

 

Acta Cryst. (2001). B57, 603-632  [ doi:10.1107/S0108768101009685 ]

Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors

P. Roussel, O. Pérez and P. Labbé

Synopsis: The present knowledge of the crystallographic and structural properties of phosphate tungsten bronzes is given. The building of this family of compounds, focused on the tilt phenomenon of the octahedra involving a great variety of structures with different symmetries as well as the existence of numerous twins, is described.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 633-637  [ doi:10.1107/S0108768101011387 ]

Ab initio determination of the valence electron distribution in the average structure of the incommensurately modulated calaverite AuTe₂

R. Caracas and X. Gonze

Synopsis: The chemical bonds and the valence electron density of the average structure of incommensurate AuTe₂ are analysed in the framework of density functional theory.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 638-645  [ doi:10.1107/S0108768101009028 ]

Experimental electron density in the triclinic phase of Co₂(CO)₆(-CO)(-C₄O₂H₂) at 120  K

R. Bianchi, G. Gervasio and D. Marabello

Synopsis: The topological analysis of the experimental electron density, determined by fitting a multipole model to high-resolution X-ray diffraction data collected at 120  K, confirms the presence of a `closed-shell' Co-Co bond in the title compound.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 646-651  [ doi:10.1107/S0108768101010539 ]

A pentagonal cluster in certain approximants to decagonal quasicrystals

M. Boström and S. Hovmöller

Synopsis: The occurrence of a pentagonal cluster in several approximants to decagonal quasicrystals is discussed. The cluster is the main constituent of the decagonal approximant structure types Al₃Mn, Al₆₀Mn₁₁Ni₄ and Ga₁₃₇Mn₁₂₃.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 652-664  [ doi:10.1107/S0108768101009879 ]

Charge distribution as a tool to investigate structural details. II. Extension to hydrogen bonds, distorted and hetero-ligand polyhedra

M. Nespolo, G. Ferraris, G. Ivaldi and R. Hoppe

Synopsis: An extension of the charge distribution method is presented, which exploits the iterative calculation of the effective coordination number, a specific contraction parameter for the hydrogen bonds and iterative scale factors for hetero-ligand polyhedra. Iteration allows the analysis of rather distorted coordination polyhedra through their charge distribution. Applications to oxides of pentacoordinated cations are shown. A computer program is available.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 665-672  [ doi:10.1107/S0108768101011685 ]

Bulk modulus and non-uniform compression of Nb₃Te₄ and In_xNb₃Te₄ (x < 1) channel compounds

M. Wunschel, R. E. Dinnebier, S. Carlson and S. van Smaalen

Synopsis: X-ray powder diffraction with synchrotron radiation is used to study the pressure dependences of the crystal structures of Nb₃Te₄ and In_xNb₃Te₄ (x = 0.54) between 0 and 40  GPa.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 673-679  [ doi:10.1107/S010876810101237X ]

Disordered crystal structure of pentamethylcyclopentadienylsodium as seen by high-resolution X-ray powder diffraction

C. Tedesco, R. E. Dinnebier, F. Olbrich and S. van Smaalen

Synopsis: The crystal structure of pentamethylcyclopentadienylsodium (NaCp*) has been determined from high-resolution X-ray powder diffraction. The crystal structure consists of polymeric multidecker chains along the crystallographic a axis. The pentamethylcyclopentadienyl anions are coplanar with each other and show twofold rotational disorder.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 680-691  [ doi:10.1107/S0108768101011193 ]

Perchlorophenalenyl radical, C₁₃Cl₉: a modulated structure with nine threefold-symmetric molecules in the asymmetric unit

P. A. Koutentis, R. C. Haddon, R. T. Oakley, A. W. Cordes and C. P. Brock

Synopsis: The strongly ruffled, odd-alternant radical C₁₃Cl₉ stacks along crystallographic threefold axes, but the intrastack spacing is too large for the material to be a good conductor. The spacing is determined by interstack interactions, which are also responsible for the structural modulations.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 692-696  [ doi:10.1107/S0108768101010527 ]

Determination of the structure of 2(benzene-1,3,5-tricarboxylic acid)·1.5(pyrene)·2(methanol) and comparison with that of 2(benzene-1,3,5-tricarboxylic acid)·pyrene·2(ethanol)

F. H. Herbstein, M. Kapon and V. Shteiman

Synopsis: A detailed comparison is made of the structures of 2(benzene-1,3,5-tricarboxylic acid)·1.5(pyrene)·2(methanol) (new determination) and of 2(benzene-1,3,5-tricarboxylic acid)·pyrene·2(ethanol) (data from the literature).

Online 29 September 2001

    

Acta Cryst. (2001). B57, 697-704  [ doi:10.1107/S010876810101151X ]

Polymorphism of maleic hydrazide. I

A. Katrusiak

Synopsis: The third polymorph of maleic hydrazine (MH3) is monoclinic, space group P2₁/n, with the same pattern of hydrogen-bonded lactam-lactim tautomers as the two previously studied polymorphs, the triclinic MH1 and the monoclinic MH2. The interplay between the distortions of the hydrogen-bonded aggregates, their arrangements and symmetries of the polymorphs is analysed.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 705-713  [ doi:10.1107/S0108768101009624 ]

Self-association and stereochemistry study of 2-methylthio-, 2-dimethylaminocyclohexanone oximes and the parent cyclohexanone oxime

P. R. Olivato, D. S. Ribeiro, J. Zukerman-Schpector and G. Bombieri

Synopsis: The crystal structures of two 2-substituted cyclohexanone oximes and of the parent cyclohexanone oxime are reported and discussed in terms of three different types of hydrogen-bond patterns along with the _C=N/*_C-X orbital interaction which stabilizes the axial conformation of the 2-substituted oximes.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 714-721  [ doi:10.1107/S0108768101013234 ]

Studies of molecular structure parameters of 20-piperidin-2-yl-5-pregnan-3,20-diol and its N-methyl derivative: two inhibitors of ²⁴⁽²⁵⁾ sterol methyl transferase and ^24(24') sterol methyl reductase of Trypanosoma cruzi

R. Atencio, G. Visbal, S. Pekerar, J. Papale and J. A. Urbina

Synopsis: Molecular structural parameters of two potential drugs against Trypanosoma cruzi epimastigotes have been studied using a combination of a stereoselective route, spectroscopic characterization and single-crystal X-ray analysis.

Online 29 September 2001

 

Acta Cryst. (2001). B57, 722  [ doi:10.1107/S0108768101012563 ]

Space-group changes: a revision to a revision

R. E. Marsh and R. A. Sparks

Synopsis: The space group for the entry under the reference codes FEBMUU and FEBMUU01 in the Cambridge Structural Database should be further corrected to space group C2/c rather than P1 (FEBMUU) or C2 (FEBMUU01).

Online 29 September 2001

 

Acta Cryst. (2001). B57, 723  [ doi:10.1107/S0108768101013118 ]

The weak hydrogen bond in structural chemistry and biology

Online 29 September 2001