Search

Discusses developments for "Acta Crystallographica Section C" as of February 2004. Downward trend in publication times; Changes in the policy on submission of articles for publication.

The title compound, [Cd(C6H4NO2)2(H2O)2]n, forms a one-dimensional chain structure based on a Cd atom with approximate pentagonal bipyramidal coordination geometry and two nicotinate ligands in different coordination modes. One acts as a tridentate ligand, chelating one Cd atom through the carboxylate group while simultaneously binding to a second symmetry-related Cd atom through the pyridine N atom; the other acts only as a bidentate ligand through its carboxylate group. Hydrogen bonds utilizing the coordinated water molecules, uncoordinated nitrogen and carboxylate O atoms as acceptors link the chains. [ABSTRACT FROM AUTHOR]

Analyzes the crystal structure of several complexes of barium. Temperature-dependent crystal cell parameters of 18-crown-6 complex with barium(II) phenolate derivatives; X-ray crystal structure determination of barium(I); Crown fragment of the neutral moiety.

Crystal structures are reported for three isomeric compounds, namely 2-(2-hydroxy­phenyl)-2-oxazoline, (I), 2-(3-hydroxy­phenyl)-2-oxazoline, (II), and 2-(4-hydroxy­phenyl)-2-oxazoline, (III), all C9H9NO2 [systematic names: 2-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (I), 3-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (II), and 4-(4,5-dihydro-1,3-oxazol-2-yl)phenol, (III)]. In these compounds, the deviation from coplanarity of the oxazoline and benzene rings is dependent on the position of the hydroxy group on the benzene ring. The coplanar arrangement in (I) is stabilized by a strong intra­molecular O—H⋯N hydrogen bond. Surprisingly, the 2-oxazoline ring in mol­ecule B of (II) adopts a 3 T4 (C2 TC3) conformation, while the 2-oxazoline ring in mol­ecule A, as well as that in (I) and (III), is nearly planar, as expected. Tetra­mers of mol­ecules of (II) are formed and they are bound together via weak C—H⋯N hydrogen bonds. In (III), strong inter­molecular O—H⋯N hydrogen bonds and weak intra­molecular C—H⋯O hydrogen bonds lead to the formation of an infinite chain of mol­ecules perpendicular to the b direction. This paper also reports a theoretical investigation of hydrogen bonds, based on density functional theory (DFT) employing periodic boundary conditions. [ABSTRACT FROM AUTHOR]

The article offers information on the submission of manuscript for the journal, and discusses papers published within the issue.

Focuses on the orthorhombic polymorphic modification of the organic compound cis-transoid-cis-dicyclohexano-18-crown-6. Structures of the two polymorphs; Shape of the centrosymmetric molecule in the monoclinic polymorph; Features of the crystal packing of the monoclinic polymorph.

Studies the crystal structure of dichloro{N-[3-([sup 5]-cyclopentadienyl propyl]-4-toluenesulfonamido-k[sup 2]N,O]-titanium. Titanium-nitrogen bond length; Reduction in the displacement of the terminal C15 atom from the cyclopentadienyl plane; Symmetric trigonal-planar geometry of the nitrogen atom.

The single-crystal X-ray diffraction structure analysis of an excellent non-linear optical material, viz. II-BaB2O4 or Ba3(B3O6)2, has been carried out at 163 and 293 K. The two sets of structural data are compared and indicate a significant shortening of the c axial length in the unit cell at 163 K, whereas the a and b axial lengths essentially do not change. [ABSTRACT FROM AUTHOR]

In the crystal structures of the title compounds, hexa­aqua­cobalt(II) tetra­aqua­diglycinato­cobalt(II) bis(sulfate), [Co(H2O)6][Co(C2H5NO2)2(H2O)4](SO4)2, (I), poly[diaqua-μ3-glycinato-di-μ4-thio­sulfato-tetra­sodium(I)], [Na4(C2H5NO2)(S2O3)2(H2O)2] n, (II), and poly[μ2-glycinato-μ4-thio­sulfato-dipotassium(I)], [K2(C2H5NO2)(S2O3)] n, (III), all atoms are located on general positions, except the Co atoms in (I), which are located on inversion centres. In (I), hydrogen bonds play an important role, while the alkali thio­sulfate compounds are characterized by three-dimensional frameworks of polyhedra. Relations to other compounds of glycine and metal sulfates are commented on. [ABSTRACT FROM AUTHOR]

The structure of brucinium dihydrogen citrate trihydrate (systematic name: 2,3-dimeth­oxy-10-oxostrychnidinium dihydrogen citrate trihydrate), C23H27N2O4+·C6H7O7−·3H2O, has been determined at 130 K. The crystallographic asymmetric unit comprises two brucinium cations, two dihydrogen citrate anions and six water mol­ecules of solvation. The two citrate anions, which are conformationally dissimilar, associate through extensive hydrogen-bonding inter­actions with the common undulating brucinium cation layer substructures and the water mol­ecules, forming a three-dimensional framework polymer. [ABSTRACT FROM AUTHOR]

In the title complex, [Ba(C10H12N5O6)2(H2O)6]n, the Ba atom is nine-coordinated by six water ligands and three carboxylate O atoms. The Ba2+ cations and the anionic glutamate ligands form coordination polymer chains, and these chains are linked by pairs of N-H…O hydrogen bonds and pairs of O-H…O hydrogen bonds to form a continuous three-dimensional framework of cations and anions, which is reinforced by hydrogen bonds involving the water molecules. [ABSTRACT FROM AUTHOR]

In piperazine-2,5-dione-oxalic acid-water (1/1/2),C4H6N2O2-C2H2O4·2H2O, both organic components lie across inversion centres in space group P&macr1;. The molecules are linked by N—H···O and by both two-centre O—H···O and three-centre O—H···(O)2 hydrogen bonds into sheets built from R²1(5), R²2(8), R44(8) and R45(15) rings. In piperazine-2,5-dione, C4H6N2O2, where the molecules lie across centres of inversion in space group P21/c, the molecules are linked by paired N—H···O hydrogen bonds into ribbons of centrosymmetric R²2(8) rings, which are further linked into sheets by C—H···O hydrogen bonds, generating R34(14) rings between the ribbons. [ABSTRACT FROM AUTHOR]

The crystal structures of three proton-transfer compounds of 5-sulfosalicylic acid (3-carboxy-4-hydroxybenzenesulfonic acid) with 4-X-substituted anilines (X = F, Cl and Br), namely 4-fluoroanilinium 5-sulfosalicylate (3-carboxy-4-hydroxyben- zenesulfonate) monohydrate, C6H7FN+·C7H5O6S¯·H2O, (I), 4-chloroanilinium 5-sulfosalicylate hemihydrate, C6H7C1-N+C7H5O6S¯0.5H2O, (II), and 4-bromoanilinium 5-sulfo-salicylate monohydrate, C6H7BrN+·C7H5O6S¯·H2O, (III), have been determined. The asymmetric unit in (II) contains two formula units. All three compounds have three-dimensional hydrogen-bonded polymeric structures in which both the water molecule and the carboxylic acid group are involved in structure extension. With both (II) and (III), which are structurally similar, the common cyclic R²2(8) dimeric carboxylic acid association is present, whereas in (I), an unusual cyclic R³3(8) association involving all three hetero- species is found. [ABSTRACT FROM AUTHOR]

The title compounds, 4-benzylamino-3-(4-methylbenzyl)-1H-1,2,4-triazol-5(4H)-one, C17H18N4O, (I), 3-(4-methylbenzyl)-4-(4-methylbenzylamino)-1H-1,2,4-triazol-5(4H)-one, C18H20-N4O, (II), and 3-(4-chlorobenzyl)-4-(4-methylbenzylamino)-1H-1,2,4-triazol-5(4H)-one, C17H17ClN4O, (III), were obtained from the corresponding Schiff base in the presence of diglyme and NaBH4. Each compound contains a 1,2,4-triazole ring and two benzene rings, which are essentially planar. The molecules are linked by a combination of intermolecular N—H···O and N—H···N hydrogen bonds. Additionally, there is a weak π-π stacking interaction in (I), involving the benzene ring of the aminobenzyl group and the partially aromatic 1,2,4-triazole moiety, with a centroid-centroid distance of 3.7397 (10) Å. [ABSTRACT FROM AUTHOR]

Unlike the related fenofibrate molecule [Henry, Zhang, Gao & Bruckner (2003). Acta Cryst. E59, 0699–0700], fenofibric acid {systematic name: 2-[4-(4-chlorobenzoyl)phenoxyl-2-methyipropanoic acid}, C17H15ClO4, contains a carboxylic acid moiety instead of an ester moiety. This polar moiety plays an important role in the formation of a rare acid-to-ketone hydrogen-bond-type packing interaction. The lack of an isopropyl group in fenofibric acid aligns the carboxyl group on the same side as the ketone carbonyl group; this conformation may play an important role in discrimination between the acid and the fenofibrate molecule in molecular recognition. [ABSTRACT FROM AUTHOR]

Brucinium L-glycerate 4.75-hydrate, C23H27N2O4+ C3H5O4-·-4.75H2O, was obtained by racemic resolution of DL-glyceric acid. This is the first report of triclinic crystals containing brucine. The water and L-glycerate anions form tapes built up of pentamers formed by water and carboxy O atoms, and this appears to be the reason for the low symmetry of the crystal. [ABSTRACT FROM AUTHOR]

In the title complexes, [Pd(C10H6O2)(C10H9N3)]·H2O, (I), and [Pd(C11H6O3)(C10H9N3)], (II), the PdII centers have a distorted cis-square-planar geometry. In (I), the Pd11atom is coordinated to two N atoms of the di-2-pyridylamine (DPA) ligand and two 0 atoms of the naphthalene-2,3-diolate (ND) dianion. In (II), the PdII atom is coordinated to two N atoms of the DPA ligand, one carboxylate 0 atom and one oxide 0 atom from the 3-oxidonaphthalene-2-carboxylate (NC) ligand. The dihedral angle between the planes of the two pyridine rings of DPA in (I) is 16.20 (12)° and that in (II) is 29.45 (10)°. In (I), the molecules are linked by N—H…O and O—H…O hydrogen bonds to generate centrosymmetric dimers. In (II), molecules are linked by N—H…O and C—H…O hydrogen bonds to generate spirals. [ABSTRACT FROM AUTHOR]

The structures of two conformationally similar 1,4-dihydropyrimidines with a novel carbamoyl substitution, viz. 6-methyl-5-(N-methylcarbamoyl)-4-phenyl-1,2,3,4-tetrahydropvrimidine-2-thione monohydrate, C13H15N3OS·H2O, (I), and 4-(4-chlorophenyl)-6-methyl-5-(N-methylcarbamoyl)-l,2,3,4-tetrahydropyrimidine-2-thione monohydrate, C13H14ClN3OS·H2O, (II), exhibit the structural features of 1,4-dihydropyridine calcium channel blockers. In both structures, the pyrimidine ring adopts a flattened boat conformation and the carbamoyl side chain is in an extended conformation with an anticlinal orientation. The phenyl ring occupies a pseudo-axial position with respect to the pyrimidine ring in these structures. Both compounds crystallize with one molecule of water, which participates in a two-dimensional hydrogen-bonding network. The molecules are linked into dimers by N-H···S hydrogen bonds in both structures. [ABSTRACT FROM AUTHOR]

In the structures of 5-(1-hydroxyethylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione, C8H10N2O4, (I), 1,3-dimethyl-5-[1-(propylamino)ethylidene]pyrimidine-2,4,6(1H,3H,5H)-trione, C11H17N3O3, (II), and 5-[1-(2,2-dimethoxyethylamino)ethylidene]-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione, C12H19N3O5, (III), there are no direction-specific intermolecular interactions. The molecules in 5-[1-(benzylamino)ethylidene]-l,3-dimethylpyrimidine-2,4,6(1H,3H,5H)trione, C15H17N3O3, (IV), are linked into chains of edge-fused rings by a combination of one C-H···O hydrogen bond and one C-H···π(arene) hydrogen bond, while the molecules in 5-(1-hydrazinoethylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione, C8H12N4O3, (V), are linked into a continuous framework structure by three distinct N-H···O hydrogen bonds, each involving a different O-atom acceptor. Each of compounds (I)-(V) contains an intramolecular hydrogen bond, of the O-H···O type in (I) and of the N-H···O type in (II)-(V). [ABSTRACT FROM AUTHOR]

The crystal structures of 3,3-dimethyl-3-(trichlorogermyl)propionic acid, [Ge(C5H9O2)Cl3], 3,3-dimethyl-3-(triphenylgermyl)propionic acid, [Ge(C6,H5)3(C5H9O2)], and 3,3dimethyl-3-(tri-p-tolylgermyl)propionic acid, [Ge(C7H7)3(C5H9O2)], have slightly distorted tetrahedral geometries about the Ge atoms. All the structures form dimers via strong O-H···O hydrogen bonds, resulting in eight-membered rings that can be best described in terms of graph-set notation R2²(8). [ABSTRACT FROM AUTHOR]

Two different zinc sulfite compounds have been prepared through the decomposition of pyrosulfite-dithionite ions in aqueous solution, viz. a dimeric complex, di-μ-sulfitoκ³O,O':O'';κ³ O: O',O''-bis [(4,4'-dimethyl-2,2'-bipyridineκ²N,N')zinc(II)] dihydrate, [Zn2(SO3)2(C12H12N2)2]·2H2O, (I), which was solved and refined from a twinned sample, and an extended polymer, poly[[aqua(1,10-phenanthroline-κ²N,N')zinc(II)]-μ3-sulfito-κ²O:O':O''-zinc(II)-μ3-sulfitoκ³O:O:O'], [Zn2(SO3)2(C12H10N2)(H2O)]n, (II). In (I), the dinuclear ZnII complex has a center of symmetry. The cation is five-coordinate in a square-pyramidal arrangement, the anion fulfilling a bridging chelating role. Compound (II) comprises two different zinc units, one being five-coordinate (square pyramidal) and the other four-coordinate (trigonal pyramidal), and two independent sulfite groups with different binding modes to the cationic centers. [ABSTRACT FROM AUTHOR]

Two new two-dimensional coordination polymers, poly[[[aqua( 2,2'-bipyridine-κ² N,N')manganese( II ) ]-µ3-p-phenylenebis(oxyacetato)-κ³O:O':O''] dihydrate], [[Man(C10H8O6)(C10H8N2)(H2O)]·2H2O]n, (I), and poly[[did-mu;-aqua-ibis[aqua sodium(I)]]-mu;4-p-phenylenebis( oxyacetato )-κO: O', O'' : O''',O'''':O'''''], [Na2(C10H8O6)(H2O)4]n, have been synthesized and characterized by X-ray single-crystal diffraction. In (I), there are two 1,4-BDOA2- [p-phenylenebis(oxyacetate) or, more commonly, benzene-1,4-dioxyacetate] ligands, each lying about inversion centres, while in (II), there is one such ligand and it also has crystallographically imposed inversion symmetry. In (I), each MnII atom displays an octahedral MnN2O4 configuration, defined by three carboxyl O atoms of different 1,4-BDOA2- groups, two N atoms of one 2,2'-bipyridine ligand and one water molecule. In (II), each NaI atom is octahedrally coordinated by one ether O atom, two carboxyl O atoms of different 1,4-BDOA2- ligands and three water molecules. The metal ions in complexes (I) and (II) are bridged by 1,4-BDOA2- groups into twodimensional layer structures. Furthermore, three-dimensional supramolecular networks are constructed via hydrogen bonds in (I) and (II), and by additional π-π stacking interactions in (I). [ABSTRACT FROM AUTHOR]

Co-crystals of the ylide (benzoylmethylene)triphenylphosphorane (BPPY) with either fumaric acid, viz. (benzoylmethylene)triphenylphosphorane-fumaric acid (2/1), C26H21OP·0.5C4H4O4, or terephthalic acid, viz. (benzoylmethylene)triphenylphosphorane-terephthalic acid (2/1), C26H21OP·0.5C8H6O4, have a stoichiometric ratio of 2:1 between the ylide and the corresponding dicarboxylic acid. In both adducts, the acid component lies across a centre of inversion. In neither case is the ylide protonated by the organic acid; instead the H atoms of the non-ionized dicarboxylic acid molecules participate in the formation of strong O-H…O hydrogen bonds with the benzoyl O atom of the ylide species. These structures are the first reported examples of co-crystals containing non-protonated BPPY. [ABSTRACT FROM AUTHOR]

In contrast to former morphological studies, the results presented here show that calcium(II) thiosulfate hexahydrate, CaS2O3·6H2O, crystallizes centrosymmetrically in the pinacoidal class (point group &1macr;). The structure is characterized by chains, parallel to [100], of alternating S2O3 and Ca(H2O)6O2 groups sharing common O atoms. The composition of each chain link is [Ca(H2O)6(S2O3)]. The geometry is analysed and compared in detail with the structural features of monoclinic strontium(II) thiosulfate pentahydrate, SrS2O3·- 5H2O, which forms layers, parallel to (100), of alternating S2O3 and Sr(H2O)4O5 groups connected via common O atoms and O-O edges. Each layer contains [Sr(H2O)3O(S2O3)]∞as the unique repeat unit. [ABSTRACT FROM AUTHOR]

Molecules of 2-nitrobenzaldehyde hydrazone, C7H7N3O2, where Z′ = 2, are linked by two N—H…N hydrogen bonds into isolated dimers, whereas in the isomeric 3-nitrobenz- aldehyde hydrazone, where Z′ = 1, the molecules are linked by one N—H…O hydrogen bond and one N—H…N hydrogen bond into a three-dimensional framework structure. [ABSTRACT FROM AUTHOR]

In the title compounds, trans-[PtI2(C11H14N2OS)2], (I), and trans-[PtBr2(C11H14N2OS)2], (II), respectively, intramolecular N-H···O (propylamine side) hydrogen bonds in the potentially bidentate thiourea ligands lock the carbonyl O atoms into six-membered rings, determining the S-monodentate mode of coordination of these ligands. Intramolecular N-H···X (X is I or Br) interactions (benzoylamine side) lead to slight distortions of the PtII coordination spheres from ideal square-planar geometry. The PtII ion is located on an inversion centre in both structures. [ABSTRACT FROM AUTHOR]

In exo-2-(3,5-dioxo-10-oxa-4-azatricyclo[ 5.2.1.02,6]dec-8-en-4-yl)phenyl acetate, C16H13NO5, the plane of the acetoxy group lies almost perpendicular to that of the phenyl ring [dihedral angle = 89.8 (1)°], in contrast with the smaller deviations found in the para isomer exo-4-(3,5-dioxo-lO-oxa-4-azatricyclo[5.2.1.02,6]dec-8-en-4-yl)phenyl acetate, C16H13NO5, these being 63.6 (1) and 37.0 (1)° for the two crystallographically independent molecules. Irrespective of the position of the acetoxy group, both compounds pack through soft CH…X (X is O or phenyl) interactions, forming interlinked centrosymmetric tetramers in the bc plane. [ABSTRACT FROM AUTHOR]

The structures of the title compounds, C12H8N2O7S and C12H8ClNO5S, contain weak C-H···O interactions creating layers of molecules which, taking the conformation of the molecules into account, are arranged in an ABAB sequence. Both structures can be designated, therefore, as ordered racemates of rotameric species. [ABSTRACT FROM AUTHOR]

The title compound, C36H35N5O7S, is found to exist in a nonspirocyclic (ring-opened) form in the crystal, although equilibrium of ring-opened and ring-closed forms (or socalled ring-chain isomerization) is possible in solution. The 4-oxocyclohexa-2,5-diene ring has a flattened sofa conformation. The N···C intramolecular separation of the atoms which would be directly bonded in a ring-closed form is quite short [2.813 (5) Å]. Topological analysis of charge density based on density-functional-theory calculations was used for consideration of shortened intramolecular contacts and indicates a strong attractive bonding interaction between these N and C atoms in the crystal structure. [ABSTRACT FROM AUTHOR]

The crystal structures of dimagnesium disodium decavanadate icosahydrate, Mg2Na2V10O28·20H2O, (I), and trimagnesium decavanadate octacosahydrate, Mg3V10O28·28H2O, (II), have been determined by single-crystal X-ray diffraction. They crystallize with monoclinic (C2/c) and triclinic (P&1macr;) symmetry, respectively. All the Mg2+ cations in (I) and (II) are octahedrally coordinated by six water molecules. The Na+ cations in (I) are coordinated by three water molecules and three O atoms of the decavanadate anions, and link the latter into a three-dimensional network. The decavanadate anions in (II) are not linked to one another. [ABSTRACT FROM AUTHOR]

Unusually large and good-quality single crystals of the synthetic trioctahedral mica KFe32+(Al0.26Fe0.763+Si3)O10(OH)2 [potassium triiron(II) aluminasilaferrate(III) decaoxide dihydroxide] have been grown hydrothermally. X-ray diffraction data measured at 270 and 100 K have been used to refine the crystal structure, including the positions of the H atoms. This synthetic mica is similar to annite, KFe3AlSi3O10(OH)2, and crystallizes with the same monoclinic C2/m symmetry. No phase transition has been observed down to 100 K. At low temperature, the ditrigonal distortion of the mica structure increases markedly, while the octahedral and tetrahedral bond lengths tend to decrease and increase, respectively. A detailed comparison of structural parameters in various Fe-rich micas is presented. [ABSTRACT FROM AUTHOR]

Describes the crystal structure of complex metal oxalate hydrates based on single crystal x-ray diffraction analysis. Chromium-oxygen distance; Octahedral coordination; Layer characteristics; Displacement ellipsoids; Linkage of oxalate groups; Hydrogen bond geometry; Geometric patterns.

Describes the crystal structure of coordination polymers with oxo-bidentate bridging ligands. Polymeric chains running in two perpendicular directions; Tetragonal space group; Packing scheme; Molecular structure.

Describes the crystal structure of tetrasubstituted pyrazine derivatives. Naphthalene ring planes; Displacement ellipsoids; Crystal packing; Short intermolecular interactions; Dihedral angles between aromatic rings.

Describes the crystal structure of dialkyl/aryl ureas. Three-dimensional network assembled by hydrogen-bonding; Eta-eta interactions; Edge-to-face interactions; Molecular arrangement along the c axis; Distorted envelope conformations.

Describes the crystal structure of molecules of N-arylaminocarbonylbenzoic acids. Aromatic eta-eta stacking interactions; Space group; Hydrogen bond; Displacement ellipsoids; Hydrogen bonding geometry.

Describes the crystal structure of hydrazone derivatives. 2,4-dinitrophenylhydrazone; 2,4-dihydroxybenzaldehyde; 2,4-dihydroacetophenone; 2,4-dihydrobenzophenone; Non-centrosymmetrical crystal system; Asymmetric unit; Displacement ellipsoids; Carbon-nitrogen bond lengths.

Describes the crystal structure of platinum(II) complexes. Hydrogen evolving centers; Crystal packing along the B axis; Displacement ellipsoids; Positional disorder of the phen ligand; Photosensitivity; Electrostatic activity; Disordered position of phen C atoms.

Describes the crystal structure of the metal-organic compound, bis[2,2'-bipyridine-kappa[sup 2]N,N']-ruthenium(II) hexacyanoferrate(III) chloride octahydrate. Alternating cationic and anionic layers along the axis; Asymmetric unit; Space group; Crystal packing along the B axis; Hydrogen bonding network; Electron transfer quenching character.

Describes the crystal structure of a metal-organic compound. Distorted octahedral geometry; Atomic displacement ellipsoid; Hydrogen bond; Electron paramagnetic resonance spectrum; Light scattering.

Describes the crystal structure of palladium compounds. Bond lengths and angles; Aromatic heterocyclic ligands; Distortion of cis-square-planar coordination geometry; Displacement ellipsoids; Molecular structure; Hydrogen bonding networks.

Examines the structures of the isomeric nucleosides 4-nitro-1-(β-D-ribofuranosyul)-1H-indazole. Conformation of glycosylic bond; Difference of crystalline state in sugar pucker; Assessment of the constituents of ribonucleosides.

Describes hydrogen-bond networks in tris(4-hydroxyphenyl)methane and its 1:1 molecular complex with 4,4'-bipyridine. Connection of C[sub 19]H[sub 16]O[sub 3] molecules by O-H...O hydrogen bonds into two-dimensional square networks that are twofold interpenetrated; Formation by trisphenol molecules of rectangular networks; Hydrogen bonding of bipyridine to phenol moieties molecules.

Describes the benzylation and nitrosation of the organic compound 4-amino-2-(methylsulfanyl)pyrimidin-6(1H)-one. Crystallization of the compound in two polymorphic forms; Linking of the molecules in (I) by a single N-H...O hydrogen bond into simple C(6) chains; Linking of chains into sheets by aromatic ππ interactions.

Describes a single-crystal neutron diffraction study at 120 and 14 K of the low temperature phase of the organic compound 1,3-dibromo-2,4,6-trimethylbenzene. Significant deviation of the molecule from the C[sub 3h] molecular symmetry encountered in tribromomesitylene even for endocyclic bond angles; Apparent C[sub 2v] molecular symmetry; Angle between the normal to the molecular plane and the normal to the (100) plane.

Describes the crystal structure of the metal-organic compound K[sup +].C[sub 9]H[sub 10]N[sub 5]O[sub6[sup -].C[sub9]H[sub 11]N[sub 5]O[sub 6].4.88H[sub 2]O. Eight-coordinate cations; One-dimensional coordination -polymer substructure built from K and O atoms in the form of chains of distorted confacial octahedra; Linking of chains into sheets by the neutral organic ligand; Linking of sheets into a single framework.

Describes the crystal structure of the organic compound diiododurene. Four centrosymmetric molecules in general positions; Molecules' violation of Kitaigorodsky's suggestion that molecules with centers of symmetry will lie on crystallographic centers of symmetry; Contact of most of the I atoms with other I atoms.

Describes the crystal structure of the organic compound cis,cis,cis-1,2,4,5-Cyclohexanetetracarboxylic acid and its dianhydride. Containment of mirror plane; Exhibition by the cyclohexane ring of a chair conformation; Formation of ring motifs by two crystallographically independent hydrogen bonds; Boat conformation of the cyclohexane ring of (II).

Describes the crystal structure of 2-(2-Naphthyloxy)acetate derivatives with potential use as antiamnesiac agents. Disordered methyl-substituted piperidine ring over two conformations in (II); Chair conformation of the piperidine ring in both compounds; Linking of the molecules in (I) by weak intermodular C-H...O interactions; Dihedral angle between naphthalene moiety and the piperidine ring.

Determines the structures of two modifications of a KH[sub 2]PO[sub 4].HF adduct at 25j0 and 150 K, and at 292 and 150 K respectively. Crystallization of the modifications from stoichiometric aqueous solutions at 295(1) and 308(3) K respectively; Location of H atoms clearly from the difference Fourier maps in each modification; Difference between modifications mainly in the arrangement of the dihydrogenphosphate anions.