issue contents

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

October 2015 issue

Highlighted illustration

Cover illustration: In a series of isomorphous compounds, [M(18-crown-6)]+ cations (M = Rb, Cs and NH4) and [SbCl6]- anions afford linear stacks, which stablize an unusual centrosymmetric structure of the macrocyclic groups, with the large cations (caesium, rubidium or ammonium) approaching the centre of the 18-crown-6 cavity. See Ponomarova, Rusanova, Rusanov & Domasevitch [Acta Cryst. (2015), C71, 867-872].

research papers


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Relatively few structural studies of the salt forms of amphetamine have been reported. The structures of (S)-amphetamine hydro­chloride and hydro­bromide are broadly similar in terms of cation conformation, the existence of three N—H⋯X hydrogen-bond contacts per anion and the overall two-dimensional hydrogen-bonded sheet motif. However, only the hydro­chloride structure features organic bilayers and Z′ > 1.

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In order to explore new metal coordination polymers and to search for new types of ferroelectrics among hybrid coordination polymers, the use of tetra­methyl­ammonium and butyl­tri­phenyl­phospho­nium cations as templates for the formation of two different manganese(II) coordination polymers with dicyanamide was investigated.

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A moderate distortion of the `picket-fence' porphyrin, (cryptand-222)potassium chlorido[meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinato]ferrate(II), [K(222)][Fe(TpivPP)Cl], was observed, with the porphyrin core showing significant doming and the Fe atom displaced by 0.62 Å from the porphyrin plane.

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The mol­ecular and crystal structures of 2,2,6,6-tetra­methyl-4-acryl­amido-1-piperidine-1-oxyl and N-(2,2,6,6-tetra­methyl­piperidin-4-yl)acryl­amide, synthesised as precursors to redox-active polymer gel systems, are reported.

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In a series of isomorphous compounds, [M(18-crown-6)]+ cations (M = Rb, Cs and NH4) and [SbCl6] anions afford linear stacks, which stablize an unusual centrosymmetric structure of the macrocyclic groups, with the large cations (caesium, rubidium or ammonium) approaching the centre of the 18-crown-6 cavity.

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Two polymorphs of 3 acetyl-4-hydroxy­coumarin differ mainly in the packing of the mol­ecules, with π–π stacking inter­actions between keto–enol hydrogen-bonded rings stabilizing the first form and the second form being stabilized by inter­actions between α-pyrone rings.

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Comparing the structures of the two complexes formed from pyrazine-2,3-di­carb­oxy­lic acid and CdII in the presence of bis­(1,2,4-triazol-1-yl)butane or bis­(1,2,4-triazol-1-yl)ethane, it seems that the length of the flexible bis­(1,2,4-triazol-1-yl)alkane ligand and the coordination modes of the pyrazine-2,3-di­carboxyl­ate anionic ligand might play key roles in determining the structures.

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In the crystal structures of four substituted-ammonium dichloride dodeca­chloro­hexa­silanes, the dodeca­chloro­hexa­silane ring is located on a crystallographic centre of inversion. The geometry of the dichloride dodeca­chloro­hexa­silanes in the different structures is almost the same, irrespective of the cocrystallized cation and solvent.

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A new CoII complex incorporating diniconazole as a ligand adopts an octa­hedral geometry, coordinated by two water O atoms and by four diniconazole N atoms. The anti­fungal activity of this complex is enhanced for Botryosphaeria ribis and Botryosphaeria berengriana, but reduced for Gibberella nicotiancola and Alternariasolani compared to that of diniconazole.

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RELi3Bi2 (RE = La–Nd, Sm, Gd, Tb) phases are challenging to synthesize and characterize, and many of the seven reported structures are the first known compounds in the respective RE–Li–Bi ternary phase diagrams.

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The adduct formed between 1,4-di­aza­bicyclo­[2.2.2]octa­ne and BrCF2CF2Br exhibits a one-dimensional polymeric structure in which the C—N⋯Br halogen-bond length is shorter than the average for related type I C—N⋯Br—C halogen-bonded systems, and shorter than found in two other reported crystal structures of related BrCF2CF2Br adducts.

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The first three-dimensional FeIII–SrII heterometallic coordination polymer was prepared by the reaction of pyridine-2,3-di­carb­oxy­lic acid (H2pydc), SrCl2·6H2O and Fe(OAc)2(OH) (OAc is acetate). One-dimensional [Fe2(pydc)4]n chains are connected by SrII cations to form a three-dimensional framework. The topology type of this framework is tfj.

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Metal complexes with Schiff base ligands have been suggested as potential phosphors in electroluminescent devices. A trinuclear zinc(II) cluster with tetradentate 6-methyl-2-({[(pyridin-2-yl)meth­yl]imino}­meth­yl)phenolate ligands exhibits a strong emission at 469 nm with a quantum yield of 15.5%.

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The crystal structure of 5-iodo­uracil has been determined in the noncentrosymmetric space group P21 on a nonmerohedrally twinned crystal. Both twin components are enanti­omorphically pure, but the twin element is a mirror plane perpendicular to c*.

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Tables, in the form of a spreadsheet for use on a computer, enable the determination of space group for single crystals, twinned crystals and crystals with a specialized metric.

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The crystal structures of three related δ-keto esters have been analysed and compared with a previously known structure. Two of the structures have cyano–halogen interactions. A Cambridge Structural Database analysis of the geometric aspects of cyano–halogen interactions idindicates that all the short cyano–halogen contacts in the CSD can be classified as halogen bonds, which are directional noncovalent interactions.

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Two new one-dimensional CuII coordination polymers containing a C2h-symmetric 1,1′:4′,1′′-terphenyl-3,3′-di­carboxyl­ate linker were both obtained from different preparation methods: one reaction was performed in the presence of 1,4-di­aza­bicyclo­[2.2.2]octane (DABCO) as a potential pillar ligand and the other was carried out in the absence of the DABCO pillar.

Special and virtual issues

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Acta Crystallographica Section C is planning special issues on

NMR Crystallography

Scorpionates: a golden anniversary

Full details are available on the special issues page.

The latest virtual issue features Coordination polymers, with an introduction by Len Barbour.

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