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Journal logoSTRUCTURAL
CHEMISTRY
ISSN: 2053-2296

July 1999 issue

Highlighted illustration

Cover illustration: Three anionic polymeric networks: sodium(I)-ruthenium(III), sodium(I)-rhodium(III) and sodium(I)-aluminium(III) mu-oxalato complexes with tris(2,2'-bipyridine)ruthenium(II) cations, see Pellaux, Decurtins & Schmalle, pages 1075-1079. Displacement ellipsoids are shown at the 50% probability level.

cif-access (inorganic compounds)


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Low-temperature potassium iron germanium tetraoxide is a stuffed tridymite derivative with a completely disordered Fe/Ge tetrahedral distribution.

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The low-temperature β-KFeSiO4 (potassium iron silicate) polymorph crystallizes with a kalsilite-type structure having P6322 symmetry and a disordered Fe/Si tetrahedral distribution.

cif-access (organic compounds)


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The title compound was obtained as a by-product of the reaction of pinacolone and 4-iodoanisole. The crystal structure was determined at 120(2)K. The molecule is bisected by a mirror plane (space group Pnma).

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The molecular structure of 4,5-dibromophthalic acid monoethyl ester is normal. The carboxylic acid group is rotated 12.8° and the ethoxycarbonyl group 69.0° out of the mean plane of the benzene ring.

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The ribofuranose ring in the title compound has a C2'-endo envelope conformation. The crystal packing consists of intermolecular hydrogen-bonding and phenyl⋯phenyl interactions.

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The structure of the title compound is isostructural with 1-deoxy-1-phenyl-β-D-ribofuranose [Matulic-Adamic et al. (1996). J. Org. Chem. 61, 3909–3911]. The ribofuranose ring has a C2'-endo,C3'-exo twist conformation.

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The two crystallographically independent conformations of the title compound differ only by the rotational positions adopted by their methoxymethyl substituents. Intermolecular contacts are dominated by hydrogen bonding involving the amine H atoms.

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The title compound, ethyl 2-(1,2,3,4,5,6,11,11a-octahydro-3- methyl-1\,4-dioxopyrazino[1\,2-b]isoquinolin-2-yl)-4-phenylbutanoate, is formed due to cyclization of quinapril in solution. The configurations at the three chiral centres are all S. The six-membered B and C rings assume half-chair and boat confirmations, respectively. The molecules in the lattice are stabilized by van der Waals contacts.

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The title compounds, C15H20O2, (I), and C15H22O3.CH3OH, (II), were obtained by intramolecular cyclization of the 5- and 3-acetonyl derivatives of 4-methylbicyclo[6.3.0]undecane-2,6-dione, respectively. Dione (I) is an ophiobilin-like C5–C8–C5 fused-ring compound and diol (II) is a C5–C6–C5–C5 tetracyclic compound.

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Biphenylene is one of the key compounds in the discussion of bond localization in aromatic systems, usually addressed as the Mills–Nixon effect [Mills & Nixon (1930). J. Chem. Soc. p. 2510]. A pronounced bond localization due to the Mills–Nixon effect in the direction of one of the Kekule forms is established. Compared with the previous structure determination by Fawcett & Trotter [Acta Cryst. (1966), 20, 87-93], the significance of bond-length alternation in relation to the s.u.'s in the six-membered rings has been dramatically increased.

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The title compound crystallizes with two nearly identical molecules in the asymmetric unit. The molecules essentially exhibit mirror symmetry.

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In the title compounds, C10H8C12N4 (R= H), (I), and C18H20C12N4O2 (R = COCHMe2), (II), the dihedral angle between the imidazolidine and phenyl rings are 67.7(1) and 70.34(9)°, respectively. In (I), the imidazolidine ring adopts a half-chair conformation, whereas in (II), it is in a flattened envelope conformation.

inorganic compounds


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The structure of Na2Ca2Nb4O13 consists of perovskite-type layers with a thickness corresponding to four perovskite cubes. The interlayer structure is of the rock-salt-type, composed of Na and O atoms. The atomic configuration suggests a ferroelectric nature along the b axis.

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β-Ba5Sb4 displays a more symmetrical arrangement than α-Ba5Sb4 (Pnma). It contains two anionic moieties, Sb24− and Sb3−, lying in tricapped and distorted monocapped trigonal prisms of Ba atoms, respectively.

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The reaction of K2S3, tellurium and sulfur yields light-yellow single crystals of dipotassium tellurium trisulfide, K2TeS3. The structure consists of isolated TeS32− anions, and K+ cations coordinated by six S atoms from five different TeS32− anions within distorted octahedra.

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KNa(VO3)2 adopts the pyroxene structure with K+ and Na+ cations, which lie on twofold axes, occupying the dodecahedral and octahedral cavities, respectively.

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Acta Cryst. (1999). C55, 1175-1176
doi: 10.1107/S01082701990