(IUCr) Contents for Acta Crystallographica Section B Vol. 64 Part 2 (April 2008)

Acta Cryst. (2008). B64, 131-143 [ doi:10.1107/S0108768108001924 ]

Kaolin polytypes revisited ab initio

P. H. J. Mercier and Y. Le Page

Synopsis: Re-examination and quantum optimization of kaolin layer stackings allow the construction of a rough enthalpy versus pressure graph with 36 stackings where kaolinite and dickite are low-energy solutions, whereas nacrite and HP-dickite are low-enthalpy solutions at moderate pressures; minor temperature dependence of this calculated 0 K graph would explain the bulk of the current observations for synthesis, diagenesis and transformation of kaolin minerals. The ideal model of nacrite is one member of a homometric but energy-distinguishable pair, whereas its literature-printed structure is correctly that of the stable member.

Online 14 March 2008

Acta Cryst. (2008). B64, 144-153 [ doi:10.1107/S0108768108001213 ]

Disordered misfit [Ca₂CoO₃][CoO₂]_1.62 structure revisited via a new intrinsic modulation

H. Muguerra, D. Grebille and F. Bourée

Synopsis: A new structural model has been determined for the [Ca₂CoO₃][CoO₂]_1.62 misfit lamellar cobalt oxide compound. It can be described with a new commensurable modulation implied by a partial ordering within the [CoO] layer.

Online 14 March 2008

Acta Cryst. (2008). B64, 154-159 [ doi:10.1107/S0108768108005041 ]

Structures of 6H perovskites Ba₃CaSb₂O₉ and Ba₃SrSb₂O₉ determined by synchrotron X-ray diffraction, neutron powder diffraction and ab initio calculations

B. Rowda, M. Avdeev, P. L. Lee, P. F. Henry and C. D. Ling

Synopsis: Ba₃CaSb₂O₉ and Ba₃SrSb₂O₉ are 6H perovskites with monoclinic C2/c and triclinic $P\bar 1$ symmetries, respectively. Their distortions from the ideal hexagonal P6₃/mmc symmetry of Ba₃MgSb₂O₉ are due to the increasing size of the alkaline-earth cation in the perovskite B site from Mg²⁺ to Ca²⁺ to Sr²⁺.

Online 14 March 2008

Acta Cryst. (2008). B64, 160-171 [ doi:10.1107/S0108768108001870 ]

KSm(MoO₄)₂, an incommensurately modulated and partially disordered scheelite-like structure

A. Arakcheeva, P. Pattison, G. Chapuis, M. Rossell, A. Filaretov, V. Morozov and G. Van Tendeloo

Synopsis: The new incommensurately modulated scheelite-like structure of KSm(MoO₄)₂ with partially disordered K and Sm has been refined by the Rietveld method. Anisotropic microstrain line-broadening has been applied to the profile refinement of the powder diffraction measurement. The fit is greatly improved in comparison with standard isotropic line-broadening.

Online 14 March 2008

Acta Cryst. (2008). B64, 172-176 [ doi:10.1107/S0108768108004175 ]

Crystal architecture of R₂SnS₅ (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides

M. Daszkiewicz, L. D. Gulay and V. Y. Shemet

Synopsis: The crystal architecture of R₂SnS₅ (R = Pr, Nd, Gd and Tb) is discussed.

Online 14 March 2008

Acta Cryst. (2008). B64, 177-186 [ doi:10.1107/S0108768108002760 ]

Sr_4 + nMn³⁺₄Mn⁴⁺_nO_10 + 3n: a new homologous series of oxygen-vacancy-ordered perovskites built from Mn³⁺O₅ pyramids and Mn⁴⁺O₆ octahedra

L. Suescun and B. Dabrowski

Synopsis: A new homologous series of oxygen-vacancy-ordered perovskite compounds with the formula Sr $_{4+n}$ Mn $^{3+}_4$ Mn $^{4+}_n$ O $_{10+3n}$ is described. Rules for generating these compounds are given in the form of simple building blocks formed by Mn³⁺O₅ pyramids and Mn⁴⁺O₆ octahedra. Related compounds in the CaMnO_x and LaCuO_x systems have also been identified as members of the proposed series.

Online 14 March 2008

Acta Cryst. (2008). B64, 187-195 [ doi:10.1107/S0108768108005211 ]

Cis/trans isomers of PtX₂L₂ (X = halogen, L = neutral ligand); the crystal structures of two polymorphs of cis-dichlorobis(dibenzyl sulfido-S)platinum(II) in the temperature range 100-295 K

C. Hansson, M. Lindqvist and Å. Oskarsson

Synopsis: The crystal structures of two polymorphs of cis-PtCl₂(Bz₂S)₂ at 295, 250, 200, 150 and 100 K are reported with emphasis on crystal packing. The structural class distribution for cis-PtX₂L₂ (X = halogen, L = neutral ligand) is given together with an analysis of the trans and cis influence in cis/trans-PtCl₂L₂ complexes.

Online 14 March 2008

Acta Cryst. (2008). B64, 196-205 [ doi:10.1107/S0108768107061770 ]

Structure-directing weak phosphoryl XHO=P (X = C, N) hydrogen bonds in cyclic oxazaphospholidines and oxazaphosphinanes

A. van der Lee, M. Rolland, X. Marat, D. Virieux, J.-N. Volle and J.-L. Pirat

Synopsis: Cyclic oxazaphospholidines and oxazaphosphinanes develop linear molecular chains bonded by relatively weak XHO=P interactions (X = C, N); the chains themselves are sometimes weakly linked by CH $\cdots\pi$ or other CHO interactions.

Online 14 March 2008

Acta Cryst. (2008). B64, 206-216 [ doi:10.1107/S0108768108000232 ]

Conformations of substituted benzophenones

P. J. Cox, D. Kechagias and O. Kelly

Synopsis: The inclinations of the two aryl rings (ring twists) in a series of 104 benzophenone molecules have been examined. Six new benzophenone structures are incorporated into the study including 2,2'-dihydroxy-4,4'-dimethoxybenzophenone that appears to have the smallest reported twist angle of any substituted benzophenone reported to date.

Online 14 March 2008

Acta Cryst. (2008). B64, 217-222 [ doi:10.1107/S0108768108000190 ]

Molecular and crystalline structure of cycloheptanespiro-3'(4'H)-6',7',8',9'-tetrahydrocyclohexa[b][1,4]thiazole-2'(5'H)-thione from powder synchrotron X-ray diffraction data

E. E. Avila, A. J. Mora, G. E. Delgado, R. R. Contreras, A. N. Fitch and M. Brunelli

Synopsis: The molecular and crystal structure of a new nitrogen-sulfur pro-ligand used in the design of metal organic compounds with potential applications in inorganic biomimetic catalysis, cycloheptanespiro-3'(4'H)-6',7',8',9'-tetrahydrocyclohexa[b][1,4]thiazole-2'(5'H)-thione, was solved and refined using synchrotron powder X-ray diffraction data.

Online 14 March 2008

Acta Cryst. (2008). B64, 223-229 [ doi:10.1107/S010876810800219X ]

Pseudopolymorphism of N-acetyl-L-phenylalanine methyl ester

A. Janik, M. Jarocha and K. Stadnicka

Synopsis: Two pseudopolymorphs of N-acetyl-L-phenylalanine methyl ester were obtained, namely an anhydrous orthorhombic phase and a hemihydrate tetragonal phase. Spontaneous re-crystallization of the anhydrous compound to the hemihydrate is observed in the presence of a trace amount of water.

Online 14 March 2008

Acta Cryst. (2008). B64, 230-239 [ doi:10.1107/S0108768108000268 ]

Deuterated -malonic acid: its neutron crystal structure in relationship to other polymorphs of aliphatic dicarboxylic acids

R. K. McMullan, W. T. Klooster and H.-P. Weber

Synopsis: Three complete neutron diffraction datasets have been collected on deuterated malonic acid single crystals, DOOC(CD₂)COOD, above (153 K), just below (56 K) and further below (50 K) the low-temperature phase transition (T_c = 56.5 K). The full structural details, determined from refinements including higher-order displacement tensors, are related to those from other aliphatic dicarboxylic acids subject to polymorphism.

Online 14 March 2008

Acta Cryst. (2008). B64, 240-248 [ doi:10.1107/S0108768108004813 ]

Structures of mono-unsaturated triacylglycerols. III. The -2 polymorphs of trans-mono-unsaturated triacylglycerols and related fully saturated triacylglycerols

J. B. van Mechelen, R. Peschar and H. Schenk

Synopsis: The [beta] -2 crystal structures of a series of saturated and trans-mono-unsaturated triacylglycerols have been solved from high-resolution powder synchrotron diffraction data. Most postulations about the packing of these polymorphs are confirmed.

Online 14 March 2008

Acta Cryst. (2008). B64, 249-259 [ doi:10.1107/S0108768108004825 ]

Structures of mono-unsaturated triacylglycerols. IV. The highest melting '-2 polymorphs of trans-mono-unsaturated triacylglycerols and related saturated TAGs and their polymorphic stability

J. B. van Mechelen, R. Peschar and H. Schenk

Synopsis: The crystal structures of the [beta] $_1^{\prime}$ -2 polymorph of a series of mixed-chain saturated and trans-mono-unsaturated triacylglycerols have been solved from high-resolution powder diffraction data. A novel [beta] '-2 polymorph of PSS has been found and its structure has been solved.

Online 14 March 2008

Acta Crystallographica Section B

Structural Science

Volume 64, Part 2 (April 2008)

research papers

Kaolin polytypes revisited ab initio

P. H. J. Mercier and Y. Le Page

Disordered misfit [Ca₂CoO₃][CoO₂]_1.62 structure revisited via a new intrinsic modulation

H. Muguerra, D. Grebille and F. Bourée

Structures of 6H perovskites Ba₃CaSb₂O₉ and Ba₃SrSb₂O₉ determined by synchrotron X-ray diffraction, neutron powder diffraction and ab initio calculations

B. Rowda, M. Avdeev, P. L. Lee, P. F. Henry and C. D. Ling

KSm(MoO₄)₂, an incommensurately modulated and partially disordered scheelite-like structure

A. Arakcheeva, P. Pattison, G. Chapuis, M. Rossell, A. Filaretov, V. Morozov and G. Van Tendeloo

Crystal architecture of R₂SnS₅ (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides

M. Daszkiewicz, L. D. Gulay and V. Y. Shemet

Sr_4 + nMn³⁺₄Mn⁴⁺_nO_10 + 3n: a new homologous series of oxygen-vacancy-ordered perovskites built from Mn³⁺O₅ pyramids and Mn⁴⁺O₆ octahedra

L. Suescun and B. Dabrowski

Cis/trans isomers of PtX₂L₂ (X = halogen, L = neutral ligand); the crystal structures of two polymorphs of cis-dichlorobis(dibenzyl sulfido-S)platinum(II) in the temperature range 100-295 K

C. Hansson, M. Lindqvist and Å. Oskarsson

Structure-directing weak phosphoryl XHO=P (X = C, N) hydrogen bonds in cyclic oxazaphospholidines and oxazaphosphinanes

A. van der Lee, M. Rolland, X. Marat, D. Virieux, J.-N. Volle and J.-L. Pirat

Conformations of substituted benzophenones

P. J. Cox, D. Kechagias and O. Kelly

Molecular and crystalline structure of cycloheptanespiro-3'(4'H)-6',7',8',9'-tetrahydrocyclohexa[b][1,4]thiazole-2'(5'H)-thione from powder synchrotron X-ray diffraction data

E. E. Avila, A. J. Mora, G. E. Delgado, R. R. Contreras, A. N. Fitch and M. Brunelli

Pseudopolymorphism of N-acetyl-L-phenylalanine methyl ester

A. Janik, M. Jarocha and K. Stadnicka

Deuterated -malonic acid: its neutron crystal structure in relationship to other polymorphs of aliphatic dicarboxylic acids

R. K. McMullan, W. T. Klooster and H.-P. Weber

Structures of mono-unsaturated triacylglycerols. III. The -2 polymorphs of trans-mono-unsaturated triacylglycerols and related fully saturated triacylglycerols

J. B. van Mechelen, R. Peschar and H. Schenk

Structures of mono-unsaturated triacylglycerols. IV. The highest melting '-2 polymorphs of trans-mono-unsaturated triacylglycerols and related saturated TAGs and their polymorphic stability

J. B. van Mechelen, R. Peschar and H. Schenk

Acta Crystallographica Section B

Structural Science

Volume 64, Part 2 (April 2008)

research papers

Kaolin polytypes revisited ab initio

P. H. J. Mercier and Y. Le Page

Disordered misfit [Ca2CoO3][CoO2]1.62 structure revisited via a new intrinsic modulation

H. Muguerra, D. Grebille and F. Bourée

Structures of 6H perovskites Ba3CaSb2O9 and Ba3SrSb2O9 determined by synchrotron X-ray diffraction, neutron powder diffraction and ab initio calculations

B. Rowda, M. Avdeev, P. L. Lee, P. F. Henry and C. D. Ling

KSm(MoO4)2, an incommensurately modulated and partially disordered scheelite-like structure

A. Arakcheeva, P. Pattison, G. Chapuis, M. Rossell, A. Filaretov, V. Morozov and G. Van Tendeloo

Crystal architecture of R2SnS5 (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides

M. Daszkiewicz, L. D. Gulay and V. Y. Shemet

Sr4 + nMn3+4Mn4+nO10 + 3n: a new homologous series of oxygen-vacancy-ordered perovskites built from Mn3+O5 pyramids and Mn4+O6 octahedra

L. Suescun and B. Dabrowski

Cis/trans isomers of PtX2L2 (X = halogen, L = neutral ligand); the crystal structures of two polymorphs of cis-dichlorobis(dibenzyl sulfido-S)platinum(II) in the temperature range 100-295 K

C. Hansson, M. Lindqvist and Å. Oskarsson

Structure-directing weak phosphoryl XHO=P (X = C, N) hydrogen bonds in cyclic oxazaphospholidines and oxazaphosphinanes

A. van der Lee, M. Rolland, X. Marat, D. Virieux, J.-N. Volle and J.-L. Pirat

Conformations of substituted benzophenones

P. J. Cox, D. Kechagias and O. Kelly

Molecular and crystalline structure of cycloheptanespiro-3'(4'H)-6',7',8',9'-tetrahydrocyclohexa[b][1,4]thiazole-2'(5'H)-thione from powder synchrotron X-ray diffraction data

E. E. Avila, A. J. Mora, G. E. Delgado, R. R. Contreras, A. N. Fitch and M. Brunelli

Pseudopolymorphism of N-acetyl-L-phenylalanine methyl ester

A. Janik, M. Jarocha and K. Stadnicka

Deuterated -malonic acid: its neutron crystal structure in relationship to other polymorphs of aliphatic dicarboxylic acids

R. K. McMullan, W. T. Klooster and H.-P. Weber

Structures of mono-unsaturated triacylglycerols. III. The -2 polymorphs of trans-mono-unsaturated triacylglycerols and related fully saturated triacylglycerols

J. B. van Mechelen, R. Peschar and H. Schenk

Structures of mono-unsaturated triacylglycerols. IV. The highest melting '-2 polymorphs of trans-mono-unsaturated triacylglycerols and related saturated TAGs and their polymorphic stability

J. B. van Mechelen, R. Peschar and H. Schenk

Disordered misfit [Ca₂CoO₃][CoO₂]_1.62 structure revisited via a new intrinsic modulation

Structures of 6H perovskites Ba₃CaSb₂O₉ and Ba₃SrSb₂O₉ determined by synchrotron X-ray diffraction, neutron powder diffraction and ab initio calculations

KSm(MoO₄)₂, an incommensurately modulated and partially disordered scheelite-like structure

Crystal architecture of R₂SnS₅ (R = Pr, Nd, Gd and Tb): crystal structure relationships in chalcogenides

Sr_4 + nMn³⁺₄Mn⁴⁺_nO_10 + 3n: a new homologous series of oxygen-vacancy-ordered perovskites built from Mn³⁺O₅ pyramids and Mn⁴⁺O₆ octahedra

Cis/trans isomers of PtX₂L₂ (X = halogen, L = neutral ligand); the crystal structures of two polymorphs of cis-dichlorobis(dibenzyl sulfido-S)platinum(II) in the temperature range 100-295 K