issue contents

Journal logoSTRUCTURAL
ISSN: 2053-2296

April 2014 issue

Highlighted illustration

Cover illustration: The crystal structure of MgAu2Ga, showing views of the unit cell along two different directions. See Smetana, Corbett & Miller [Acta Cryst. (2014), C70, 355-358].

international union of crystallography

scientific comment

link to html
A new refinement of Ni5.20Sn8.7Zn4.16Cu1.04 based on the originally published structure factors was performed and indicates that the structure can be described in the centrosymmetric space group Pm\overline{3}m; no justification for the absence of the inversion centre could be found within the accuracy of the available data.

inorganic compounds

link to html
The crystal structure of a mixed-valence iron phosphite has been solved from single-crystal X-ray diffraction data in the trigonal space group R\overline{3}m. The compound shows anionic [Fe3(HPO3)4]2− and [Fe(HPO3)2] sheets stacked in a disordered manner along the c axis, with the K+ cations located in the inter­layer spaces.

link to html
MgAuGa is the first ternary representative of the Mg–Au–Ga system. It adopts the Fe2P structure type (Pearson symbol hP9) and closely resembles hexa­gonal Mg2Ga through a direct group–subgroup relationship. MgAu2Ga also crystallizes hexa­gonally and is isotypic with Na3As. It adopts the structure of another binary compound, viz. Mg3Au (hP8), but shows an unexpected distribution of Mg, Au, and Ga among the atomic positions of the asymmetric unit compared to Mg3Au.

metal-organic compounds

link to html
In a one-dimensional coordination polymer containing approximately square-pyramidal CuII, with one bridging and one terminal dicyanamide ligand, the polymer chains are linked by hydrogen bonds and π–π stacking inter­actions.

link to html
The four Co atoms of a novel tetra­nuclear mixed-valence cobalt complex display distorted octa­hedral coordination environments and are bridged by two 2-[(oxido­imino)­methyl]-6-meth­oxy­phenolate ligands, two 2-[(hy­droxy­imino)­methyl]-6-meth­oxy­phenolate ligands and two azide anions to form a tetra­nuclear [Co4N4O4] cluster. Adjacent clusters are connected through weak C—H⋯N and C—H⋯O inter­actions.

link to html
The structure of a new triclinic polymorph of Fe(OEP)Cl has been determined. The high-spin five-coordinate heme unit and axial ligation are essentially the same as previously determined, with an average Fe—N bond length of 2.075 (2) Å, an axial Fe—Cl bond length of 2.225 (4) Å, and the iron cation displaced by 0.494 (4) Å. Common features of the porphyrin plane–plane and supra­molecular stacking are identified. The main mol­ecular differences between the two polymorphs are in the orientations of the ethyl side chains on the periphery of the porphyrin core.

link to html
Two homochiral coordination polymers both have a three-dimensional network structure with a one-dimensional channel. An investigation of the photoluminescence properties shows that one of the compounds displays a strong emission in the purple region.

link to html
In the Ag complex of N-[(di­phenyl­phosphanyl)methyl]pyridin-4-amine (DPP) with perchlorate, the unique Ag+ cation has a near-linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. In the analogous complex with nitrate, the nitrate anions weakly chelate to each Ag+ cation, leading to each Ag+ cation having a distorted tetra­hedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms.

link to html
A sawhorse-type dinuclear ruthenium complex with two bridging perfluoro­heptan­oate ligands and two dimethyl sulfoxide ligands in the axial positions is a new example of a compound with an aliphatic fluorinated carboxyl­ate ligand and a direct Ru—Ru inter­action. The compound is an active catalyst in transvinyl­ation of propionic acid with vinyl acetate.

organic compounds

link to html
Di­hydro­berberine, a reduced form of pharmacologically important berberine, crystallizes from ethanol without inter­stitial solvent. Although lacking classical O—H or N—H donors, the packing in the crystalline state is clearly governed by C—H⋯N and C—H⋯O hydrogen bonds involving the two acetal-type C—H bonds of the 1,3-dioxole ring.

link to html
A new polymorph of the cinnamic acid–isoniazid cocrystal is characterized by hydrogen-bonded tetra­meric arrangements of two mol­ecules of isoniazid and two of cinnamic acid. Possible modification of the hydrogen bonding was investigated by changing the hydrazide group of isoniazid by an in situ reaction with acetone and cocrystallization with cinnamic acid.

link to html
In a monohydrated cocrystal of 1,3,5-tri­amino-1,3,5-tri­deoxy-cis-inositol and its hydro­iodide salt, the cation, but not the neutral inositol unit, exhibits intra­molecular O—H⋯O hydrogen bonding. The neutral and cationic inositol entities are each aligned into chains along [001]. In these chains, two O—H⋯N inter­actions generate a ten-membered ring as the predominant structural motif.

link to html
The five-membered furan­ose ring of three fluoro- or chloro-substituted 1′-de­oxy-1′-phenyl-β-D-ribo­furan­oses has a conformation between a C2′-endo,C3′-exo twist and a C2′-endo envelope. The ribo­furan­ose groups are connected by O—H⋯O hydrogen bonds to symmetry-related mol­ecules to form layers. The orientation of the benzene ring is independent of the substitution pattern of the ring and depends mainly on crystal-packing effects.

link to html
A peptide is reported which is a left-handed helix with a right-handed conformation in the fourth residue, which is the only chiral residue. There are two 4→1 intra­molecular hydrogen bonds. In the crystal structure, mol­ecules are linked by hydrogen bonds along the c axis.

link to html
Four related compounds exemplify the reaction sequence from a 1,4-ep­oxy­benzazepine ester via its reduction product, a benzazepin-4-ol ester, and the corresponding hy­droxy carb­oxy­lic acid, to a lactone as formed by intra­molecular condensation.

link to html
Three 5,6-tri­methyl­ene­pyrimidin-4-one derivatives display a combination of N—H⋯O, N—H⋯S, C—H⋯O and C—H⋯N hydrogen bonds. The study of the mol­ecular and supra­molecular structures of thio­uracil derivatives is significant in the development of lipoprotein-associated phospho­lipase A2 inhibitors.

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?

Follow Acta Cryst. C
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds