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Journal logoSTRUCTURAL SCIENCE
CRYSTAL ENGINEERING
MATERIALS
ISSN: 2052-5206

December 2014 issue

Highlighted illustration

Cover illustration: A representation of C-(A)-S-H(I), which is a model for the main binding phase in concrete. The structure consists of layers of Ca-O polyhedra (light blue, shaded) that have (alumino)silicate chains (dark blue, shaded) clasped to each side; the chains are of infinite length on one side (and kinked to produce a repeat of three tetrahedra), and dimeric on the other side. The chains are viewed end-on. Additional Ca ions and water molecules occur in the interlayer space (light blue, unshaded octahedra). See Fig. 13 of Richardson [(2014), Acta Cryst. B70, 903-923].

research papers


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C-(A)-S-H(I) is a structurally imperfect form of 14 Å tobermorite that is studied extensively as a model for the main binding phase in concrete. Crystal-chemically plausible structures are developed that account for a wide range of experimental observations, including variations in calcium to silicon ratio, water to silicon ratio, (alumino)silicate anion structure and layer spacing.

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Distorted Archimedian polyhedron in (NH4)3TiF7 as the superposition of TiF6 octahedra disordered among four postions.

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The heterometal distribution over the cyclic {Cr7M} cage molecule is partly ordered over the molecular wheel in the crystal structure of [NH2Et2][Cr7MF8(tBuCO2)16][C4H8O2]0.5 for the divalent transition metals M = Mn, Fe, Co, Ni, Cu, Zn and Cd.

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The contrasting behaviour of N-(carboxymethyl) maleamic acid and N-carbamyl maleamic acid under cyclodehydration conditions are discussed in the light of X-ray diffraction and modelling studies.

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Single-crystal neutron diffraction, ab initio calculations and Raman spectroscopy are applied to understand the structure and hydrogen bonding of ammonium carbonate monohydrate, a hitherto poorly characterized substance, particularly in relation to other ammonium-bearing compounds.

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The structure of an extremely rare 1M polytype of the 1:1 layer silicate cronstedtite from Eisleben (Saxony-Anhalt, Germany) was refined against a single-crystal X-ray data set. The deformation parameters of tetrahedral and octahedral sheets, arrangement of hydrogen bonds, stacking rule and desymmetrization are presented and discussed.

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High-resolution crystal structure determination and refinement of 1-(4′-chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carbonitrile revealed the presence of 2.5% of its bromine derivative, which would not be found using standard resolution data (ca 0.8 Å), as disorder was visible only at high resolution.

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The electron-density distribution in Cu2O has been critically reexamined to test controversial conclusions from earlier experimental and theoretical studies.

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Chain polymers crystallize from aqueous solutions of CaII and MnII halides with enantiopure or racemic alanine to form a series of closely related structure types.

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The crystal structure of the novel Al77Rh15Ru8 phase (which is an approximant of decagonal quasicrystals) was determined from automated electron diffraction tomography (ADT) data. It has one of the most complicated intermetallic structures solved solely by electron diffraction methods.

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Metal–metal-bonded dirhodium complexes with four chelating biimidazole ligands at equatorial sites and two axial ligands gave novel assembled structures with common inorganic anions.

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The accuracy of 215 experimental organic crystal structures from powder diffraction data is validated against a dispersion-corrected density functional theory method.

short communications


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Impurities in the form of surface-terminating H atoms and/or functional groups are indispensible for the stabilization of a diamond structure in nanodiamond particles.

obituaries


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Obituary for Frank H. Allen.
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