issue contents

Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

December 2015 issue

Highlighted illustration

Cover illustration: A new route for the synthesis of phosphate esters with a retained six-membered ring produced 2,2'-[benzene-1,2-diylbis(­oxy)]bis­(5,5-dimethyl-1,3,2-dioxaphosphinane) 2,2'-dioxide in which two 1,3,2-dioxaphosphinane groups are linked through a catechol group. The conformations about the two catechol O atoms are quite different. See Said, Ali & Hughes [Acta Cryst. (2015), C71, 1037-1041].

research papers


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In a linear chain structure composed of square-planar [Pt(en)2]2+ (en is ethyl­ene­di­amine) and elongated octa­hedral trans-[PtCl2(en)2]2+ cations, the components are stacked alternately, bridged by Cl atoms, along the b axis. The structural parameter indicating the mixed-valence state of the Pt atom, expressed by δ = (PtIV—Cl)/(PtII⋯Cl), is 0.643.

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A new route for the synthesis of phosphate esters with a retained six-membered ring produced 2,2′-[benzene-1,2-diylbis(­oxy)]bis­(5,5-dimethyl-1,3,2-dioxaphosphinane) 2,2′-dioxide in which two 1,3,2-dioxaphosphinane groups are linked through a catechol group. The conformations about the two catechol O atoms are quite different.

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The crystal structure determinations of β-resorcylic acid hydrate and thymine–β–resorcylic acid hydrate were undertaken in order to study the synthon preference. In the former, an acid–acid homosynthon and in the latter an amide–acid heterosynthon are observed.

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The cocrystallized solvent has a marked influence on the spin-transition properties of {tris­[4-(1H-pyrazol-3-yl)-3-aza­but-3-en­yl]amine}­iron(II) bis­(tetra­fluorido­borate) in the solid state. In contrast to previously published structures showing only a high-spin configuration, the methanol solvate features a strictly low-spin configuration at 100 K.

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Molecules of a new nickel(II) complex of 2-[(2,4,6-tri­meth­ylphen­yl)­imino­eth­yl]­pyrrol-1-ide are linked into an extensive network by means of inter­molecular C—H⋯π(arene) hydrogen bonds in which every mol­ecule acts both as a hydrogen-bond donor and acceptor. The supra­molecular assembly takes the form of an infinite two-dimensional sheet.

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[Ag(CN)(5,5′-dmbpy)]n (5,5′-dmbpy is 5,5′-dimethyl-2,2′-bipyridine) crystallizes in the monoclinic space group C2/c with the AgI cation on an inversion centre. Each AgI cation exhibits a distorted tetra­hedral geometry, generating a one-dimensional zigzag chain. These chains are linked together via weak nonclassical inter­molecular inter­actions, generating a two-dimensional supra­molecular network.

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Five related benzo[b]pyrimido[5,4-f]azepine derivatives all exhibit similar mol­ecular structures containing a boat conformation for the azepine ring, but all five structures show a different range of direction-specific inter­molecular inter­actions and hence different patterns of supra­molecular assembly.

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The structure of a new adenine-based ZnII two-dimensional coordination polymer incorporating thio­phene-2,5-di­carboxyl­ate ligands exhibits in its packing two-dimensional (4,4) grid sheets parallel to the ab plane, featuring two distinct square cavities delimited by the two types of ligands and the ZnII ions. The complex shows enhanced photoluminescence intensity compared to the free ligands.

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Structural characterization of 2-nicotinamido-1,3,4-thia­diazole (TGN-020) was completed using X-ray crystallographic techniques and 1H and 13C NMR spectroscopic assignments were made using 1D and 2D NMR methods. Parameters for blood–brain barrier permeability were also determined using computation methods.

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A crystal harvested directly from a bottle of nasal spray, in which the active ingredient is delivered in the solid state and is stated to be crystals of the orthorhombic anhydride of mometasone furoate suspended in aqueous solution. Determination of the unit cell revealed that the crystal found in the bottle was, in fact, not the polymorph described in the product monograph, but rather the triclinic monohydrate.

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2-Acyl­ated 2,3,1-benzodi­aza­borines can display unusual structures and reactivities. The crystal structure analysis of the boron heterocycle obtained by condensing 2-formyl­phenyl­boronic acid and picolinohydrazide reveals it to be an N→B-chelated zwitterionic tetra­cycle. A favored yet reversible chelation equilibrium provides an explanation for the slow D2O exchange observed for the OH resonance in the 1H NMR spectrum.

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Two new ZnII coordination polymers based on 3,6-bis­(pyridin-4-yl)phenanthrene-9,10-dione displaying different coordination modes feature one-dimensional zigzag chains connected by weak C—H⋯π and π–π inter­actions to form a two-dimensional network in one polymer, and a wave-like two-dimensional layered structure with helical chains in the other.

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The structure of an iron(II) complex features coordination by an organic decomposition product, i.e. 1,1′-bis­(pyridin-2-yl)-2,2-bi(1H-imidazole), of a tetra­dentate N-heterocyclic carbene (NHC) ligand in an axial position. The decomposition product, a C—C-coupled bi­imidazole, is trapped by coordination to still-intact iron(II) complexes. Insights into the structural features of the organic decomposition products might help to improve the stability of oxidation catalysts under harsh conditions.

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The mol­ecular and crystal structures of ferrocenyl derivatives with methyl methacrylate substituents in one and both of the cyclo­penta­diene rings are reported. C—H⋯O and C—H⋯π(ring) contacts stabilize both structures and the bis­(methyl methacrylate) compound displays unusual C—H⋯π(alkene) contacts.

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Two puzzling α-dihydrazones were obtained unexpectedly through an otherwise firmly established synthetic procedure aimed at the preparation of substituted pyrazoles. Possible reasons for this anomalous behaviour are analyzed. Weak inter­molecular inter­actions are responsible for the crystal stability, from which some unusual O⋯O contacts representing a special case of `electron donor–acceptor' (EDA) inter­actions stand out.

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The achiral N-terminal unprotected tetra­peptide H-Gly-Aib-Gly-Aib-OtBu forms no intra­molecular hydrogen bonds but does form eight inter­molecular hydrogen bonds with six symmetry-related mol­ecules. The backbone conformation starts in the right-handed helical region (and the left-handed helical region for the inverted mol­ecule) and reverses the screw sense in the last two residues.

Special and virtual issues

Acta Crystallographica Section C is planning special issues on

The Structural Chemistry of Homogeneous and Heterogeneous Catalysts

NMR Crystallography

Full details are available on the special issues page.

The latest virtual issue, featuring Coordination polymers and with an introduction by Len Barbour, was published in July 2014.

What are the 'most read' articles from the recent special issues?

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