(IUCr) Contents for Acta Crystallographica Section B Vol. 58 Part 3 Number 2 (June 2002)

Acta Cryst. (2002). B58, 423-436 [ doi:10.1107/S010876810102167X ]

Observation of 4f electron transfer from Ce to B₆ in the Kondo crystal CeB₆ and its mechanism by multi-temperature X-ray diffraction

K. Tanaka and Y. Onuki

Synopsis: Multi-temperature electron density measurements of the Kondo crystal CeB₆ and analysis based on a spin-orbit interaction model revealed an entropy-driven mechanism of the 4f-electron transfer from Ce to B-B bonds connecting B₆ octahedra. The charge accumulation changes the effective atomic potentials, which causes large anharmonic vibrations of Ce and B at low temperature and an increase in entropy.

Online 29 May 2002

Acta Cryst. (2002). B58, 437-447 [ doi:10.1107/S0108768102003269 ]

Klockmannite, CuSe: structure, properties and phase stability from ab initio modeling

V. Milman

Synopsis: The crystal structure and phase stability of CuSe polymorphs under pressure is investigated using density functional formalism.

Online 29 May 2002

Acta Cryst. (2002). B58, 448-456 [ doi:10.1107/S0108768102003294 ]

On the structure of aragonite - Lawrence Bragg revisited

D. J. M. Bevan, E. Rossmanith, D. K. Mylrea, S. E. Ness, M. R. Taylor and C. Cuff

Synopsis: Aragonite has previously been described in the space group Pnma. In this work, weak reflections that violate the systematic extinctions of Pnma are shown to be Bragg reflections. A twinned triclinic model is proposed that goes some way towards explaining these weak reflections.

Online 29 May 2002

Acta Cryst. (2002). B58, 457-462 [ doi:10.1107/S0108768102002689 ]

Anion packing density: a universal quantity for both dense and porous crystalline inorganic phases

F. Liebau and H. Küppers

Synopsis: To compare densities or porosities of inorganic phases of almost any kind, the anion packing density is introduced and compared with the framework density used by zeolite scientists. It becomes evident that the Shannon-Prewitt effective ionic radii are inadequate to quantitatively describe inroganic structures at high pressures.

Online 29 May 2002

Acta Cryst. (2002). B58, 463-470 [ doi:10.1107/S0108768102002410 ]

Nucleophilic addition reaction in coordinated non-linear pseudohalides: experimental charge density analysis in trans-bis(cyanamidonitrato-N:O)bis-(imidazole-N³)copper(II) complex

J. Kozísek, N. K. Hansen and H. Fuess

Synopsis: Structural, multipole and orbital analyses of the electron density for the title complex using high-resolution X-ray diffraction data collected at 120 K have been performed. Analysis of the atomic charges indicates the possibility of nucleophilic addition reaction.

Online 29 May 2002

Acta Cryst. (2002). B58, 471-476 [ doi:10.1107/S0108768102001052 ]

Crystal and electronic structure of a new metallic modification of (ET)₂[KHg(SCN)₄]

O. N. Kazheva, E. Canadell, G. G. Aleksandrov, N. D. Kushch and O. A. Dyachenko

Synopsis: The crystal and electronic structures of a new polymorphous metallic modification of the (ET)₂[KHg(SCN)₄] salt have been determined, using X-ray diffraction and tight-binding band structure calculations.

Online 29 May 2002

Acta Cryst. (2002). B58, 477-481 [ doi:10.1107/S0108768102001039 ]

Refinement of obverse/reverse twins

R. Herbst-Irmer and G. M. Sheldrick

Synopsis: Two examples of the refinement of obverse/reverse twinned structures are discussed. The second example shows additional merohedral twinning.

Online 29 May 2002

Acta Cryst. (2002). B58, 482-488 [ doi:10.1107/S0108768102001970 ]

Reversible dimerization of C₆₀ molecules in the crystal structure of the bis(arene)chromium fulleride [Cr(C₇H₈)]₂C₆₀

A. Hönnerscheid, R. Dinnebier and M. Jansen

Synopsis: Bis(arene)chromium fulleride [Cr(C₇H₈)₂]⁺C₆₀^- exhibits a reversible first-order phase transition forming (C₆₀)₂^2- dimers. The structures of the high- and low-temperature phase are determined via high-resolution X-ray powder diffraction and are compared with the structures of Rb⁺C₆₀^-, the other prominent example in which (C₆₀)₂^2- dimers are present.

Online 29 May 2002

Acta Cryst. (2002). B58, 489-493 [ doi:10.1107/S0108768101021814 ]

Fast estimation of crystal densities

D. W. M. Hofmann

Synopsis: By a least-squares fit the average volume of elements in organic and metal-organic crystals is determined as a function of the temperature and a method for fast density estimation and its mean error is presented.

Online 29 May 2002

Acta Cryst. (2002). B58, 494-501 [ doi:10.1107/S0108768102001854 ]

Novel, predicted patterns of supramolecular self-assembly, afforded by tetrameric rings of C₂ symmetry in the crystal structures of 2-hydroxy-1-cyclopentanecarboxylic acid, 2-hydroxy-1-cyclohexanecarboxylic acid and 2-hydroxy-1-cycloheptanecarboxylic acid

A. Kálmán, L. Fábián, G. Argay, G. Bernáth and Z. Gyarmati

Synopsis: Racemic crystals of three optically active molecules formed by saturated five-, six- and seven-membered rings bearing two vicinal (either cis or trans) hydrogen-bond donor/acceptor functions were found to represent a novel form of supramolecular close packing. It had been predicted on the basis of five related patterns of close packing revealed in analogous cyclopentane derivatives.

Online 29 May 2002

Acta Cryst. (2002). B58, 502-511 [ doi:10.1107/S0108768102000630 ]

Two phases of C₉H₁₂O₄: why is the structure at 295 K so complicated?

L. L. Duncan, B. O. Patrick and C. P. Brock

Synopsis: The structures of two modulated phases of a small organic molecule have been determined. The structure at 295 K has five mirror-symmetric molecules in the asymmetric unit; four of the molecules are disordered. At 130 K the unit cell and asymmetric unit are smaller and the structure is ordered.

Online 29 May 2002

Acta Cryst. (2002). B58, 512-518 [ doi:10.1107/S010876810200277X ]

Turns, water cage formation and hydrogen bonding in the structures of L-valyl-L-phenylalanine

C. H. Görbitz

Synopsis: Two L-Val-L-Phe structures present unique dipeptide conformations and crystal packing arrangements, provide comprehensive hydrogen-bond data and display detailed interactions between hydrophobic groups and solvent water molecules.

Online 29 May 2002

Acta Cryst. (2002). B58, 519-529 [ doi:10.1107/S0108768102004020 ]

Charge density study of hydrogen [(2,4-diaminopyrimidin-1-io)methyl]phosphonate monohydrate

M. Slouf, A. Holy, V. Petrícek and I. Cisarova

Synopsis: The crystal structure and charge density of hydrogen [(2,4-diaminopyrimidin-1-io)methyl]phosphonate monohydrate have been determined by means of single-crystal X-ray diffraction. Preferential polarization of lone-pair electron densities of hydrogen-bond acceptor atoms into shorter hydrogen bonds was observed.

Online 29 May 2002

Acta Cryst. (2002). B58, 530-544 [ doi:10.1107/S0108768102000642 ]

Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines

D. M. M. Farrell, G. Ferguson, A. J. Lough and C. Glidewell

Synopsis: In salt-type adducts of organic diamines with chiral or racemic malic acids, the hard hydrogen bonds can generate molecular ladders, sheets or three-dimensional frameworks. The supramolecular structures formed by the chiral acid can closely mimic centrosymmetry.

Online 29 May 2002

Acta Cryst. (2002). B58, 545-552 [ doi:10.1107/S0108768102003816 ]

Structural investigations of phosphorus-nitrogen compounds. 4. Steric and electronic effects in dibenzylamino derivatives of hexachlorocyclotriphosphazatriene and 4,4,6,6-tetrachloro-2,2-diphenylcyclotriphosphazatriene

S. Besli, S. J. Coles, D. B. Davies, M. B. Hursthouse, A. Kiliç, T. A. Mayer, R. A. Shaw and A. Uslu

Synopsis: The synthesis and crystal structures of N₃P₃Cl₅[N(CH₂Ph)₂], N₃P₃Cl₄[N(CH₂Ph)₂]₂, N₃P₃Ph₂Cl₃[N(CH₂Ph)₂] and N₃P₃Ph₂Cl₂[N(CH₂Ph)₂]₂ are reported. These compounds are included in two series of crystal structures that are used to investigate steric and electronic effects in substituted cyclophosphazenes.

Online 29 May 2002

Acta Cryst. (2002). B58, 553-563 [ doi:10.1107/S0108768102003348 ]

Planar packing of tetrachlorodicyanobenzene isomers

D. Britton

Synopsis: All three isomers of the title compound form crystalline complexes with hexamethylbenzene. For each isomer there is at least one complex in which the title compound forms a pseudo-hexagonal two-dimensional layer in which every nitrile group is in contact with Cl atoms in two adjacent molecules.

Online 29 May 2002

addenda and errata

Acta Cryst. (2002). B58, 564 [ doi:10.1107/S0108768102003506 ]

Polymorphism of maleic hydrazide. I. Erratum

A. Katrusiak

Synopsis: Erratum to Acta Cryst. (2001), B57, 697-704.

Online 29 May 2002

Acta Cryst. (2002). B58, 565 [ doi:10.1107/S0108768102003518 ]

Coupling of the lactone-ring conformation with crystal symmetry in 6-hydroxy-4,4,5,7,8-pentamethyl-3,4-dihydrocoumarin. Erratum

A. Budzianowski and A. Katrusiak

Synopsis: Erratum to Acta Cryst. (2001), B58, 125-133.

Online 29 May 2002

Acta Cryst. (2002). B58, 565 [ doi:10.1107/S0108768102008911 ]

Two fluoradene derivatives: pseudosymmetry, eccentric ellipsoids and a phase transition. Erratum

A. Xia, J. P. Selegue, A. Carrillo, B. O. Patrick, S. Parkin and C. P. Brock

Synopsis: Erratum to Acta Cryst. (2001), B57, 507-516.

Online 29 May 2002

Acta Cryst. (2002). B58, 565 [ doi:10.1107/S010876810200890X ]

Group-Theoretical Analysis of Octahedral Tilting in Perovskites. Erratum

C. J. Howard and H. T. Stokes

Synopsis: Erratum to Acta Cryst. (1998), B54, 782-789.

Online 29 May 2002

Acta Crystallographica Section B

Structural Science

Volume 58, Part 3 Number 2 (June 2002)

research papers

Observation of 4f electron transfer from Ce to B6 in the Kondo crystal CeB6 and its mechanism by multi-temperature X-ray diffraction

K. Tanaka and Y. Onuki

Klockmannite, CuSe: structure, properties and phase stability from ab initio modeling

V. Milman

On the structure of aragonite - Lawrence Bragg revisited

D. J. M. Bevan, E. Rossmanith, D. K. Mylrea, S. E. Ness, M. R. Taylor and C. Cuff

Anion packing density: a universal quantity for both dense and porous crystalline inorganic phases

F. Liebau and H. Küppers

Nucleophilic addition reaction in coordinated non-linear pseudohalides: experimental charge density analysis in trans-bis(cyanamidonitrato-N:O)bis-(imidazole-N3)copper(II) complex

J. Kozísek, N. K. Hansen and H. Fuess

Crystal and electronic structure of a new metallic modification of (ET)2[KHg(SCN)4]

O. N. Kazheva, E. Canadell, G. G. Aleksandrov, N. D. Kushch and O. A. Dyachenko

Refinement of obverse/reverse twins

R. Herbst-Irmer and G. M. Sheldrick

Reversible dimerization of C60 molecules in the crystal structure of the bis(arene)chromium fulleride [Cr(C7H8)]2C60

A. Hönnerscheid, R. Dinnebier and M. Jansen

Fast estimation of crystal densities

D. W. M. Hofmann

Novel, predicted patterns of supramolecular self-assembly, afforded by tetrameric rings of C2 symmetry in the crystal structures of 2-hydroxy-1-cyclopentanecarboxylic acid, 2-hydroxy-1-cyclohexanecarboxylic acid and 2-hydroxy-1-cycloheptanecarboxylic acid

A. Kálmán, L. Fábián, G. Argay, G. Bernáth and Z. Gyarmati

Two phases of C9H12O4: why is the structure at 295 K so complicated?

L. L. Duncan, B. O. Patrick and C. P. Brock

Turns, water cage formation and hydrogen bonding in the structures of L-valyl-L-phenylalanine

C. H. Görbitz

Charge density study of hydrogen [(2,4-diaminopyrimidin-1-io)methyl]phosphonate monohydrate

M. Slouf, A. Holy, V. Petrícek and I. Cisarova

Chiral versus racemic building blocks in supramolecular chemistry: malate salts of organic diamines

D. M. M. Farrell, G. Ferguson, A. J. Lough and C. Glidewell

Structural investigations of phosphorus-nitrogen compounds. 4. Steric and electronic effects in dibenzylamino derivatives of hexachlorocyclotriphosphazatriene and 4,4,6,6-tetrachloro-2,2-diphenylcyclotriphosphazatriene

S. Besli, S. J. Coles, D. B. Davies, M. B. Hursthouse, A. Kiliç, T. A. Mayer, R. A. Shaw and A. Uslu

Planar packing of tetrachlorodicyanobenzene isomers

D. Britton

addenda and errata

Polymorphism of maleic hydrazide. I. Erratum

A. Katrusiak

Coupling of the lactone-ring conformation with crystal symmetry in 6-hydroxy-4,4,5,7,8-pentamethyl-3,4-dihydrocoumarin. Erratum

A. Budzianowski and A. Katrusiak

Two fluoradene derivatives: pseudosymmetry, eccentric ellipsoids and a phase transition. Erratum

A. Xia, J. P. Selegue, A. Carrillo, B. O. Patrick, S. Parkin and C. P. Brock

Group-Theoretical Analysis of Octahedral Tilting in Perovskites. Erratum

C. J. Howard and H. T. Stokes

related papers

Observation of 4f electron transfer from Ce to B₆ in the Kondo crystal CeB₆ and its mechanism by multi-temperature X-ray diffraction

Nucleophilic addition reaction in coordinated non-linear pseudohalides: experimental charge density analysis in trans-bis(cyanamidonitrato-N:O)bis-(imidazole-N³)copper(II) complex

Crystal and electronic structure of a new metallic modification of (ET)₂[KHg(SCN)₄]

Reversible dimerization of C₆₀ molecules in the crystal structure of the bis(arene)chromium fulleride [Cr(C₇H₈)]₂C₆₀

Novel, predicted patterns of supramolecular self-assembly, afforded by tetrameric rings of C₂ symmetry in the crystal structures of 2-hydroxy-1-cyclopentanecarboxylic acid, 2-hydroxy-1-cyclohexanecarboxylic acid and 2-hydroxy-1-cycloheptanecarboxylic acid

Two phases of C₉H₁₂O₄: why is the structure at 295 K so complicated?