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Single-crystal X-ray Diffraction Data (single-crystal + x-ray_diffraction_data)
Selected AbstractsAbsolute configuration of eremophilane sesquiterpenes from Petasites hybridus: Comparison of experimental and calculated circular dichroism spectraCHIRALITY, Issue 3 2010Antje Bodensieck Abstract In-depth conformational analyses of 10 known eremophilane (= (1S,4aR,7R,8aR)-decahydro-1,8a-dimethyl-7-(1-methylethyl)napththalene) sesquiterpenes, 1,10, from Petasites hybridus were performed with molecular mechanics as well as density functional theory methods. Electronic transition energies and rotational strengths of these eight eremophilane lactones and two petasins were calculated by time-dependent density functional theory (B3PW91/TZVP). The absolute configurations of the constituents could be assigned by comparison of their simulated and experimental circular dichroism (CD) spectra in methanol as (4S,5R,8S,10R) (1, 2), (2R,4S,5R,8S,10R) (3, 4, 5), (2R,4S,5R,8R,9R,10R) (6), (2R,4S,5R,8R,10R) (7, 8), and (3R,4R,5R) (9, 10). Single-crystal X-ray diffraction data of 8,-hydroxyeremophilanolide ((8S)-8-hydroxyeremophil-7(11)-en-12,8-olide) (1) served as starting point for the theoretical conformational calculations of the 8,-epimers of the eremophilane lactones. Experimental CD spectra as well as 1H NMR spectra of compound 1 in methanol were considerably dependent on sample concentration. Chirality, 2010. © 2009 Wiley-Liss, Inc. [source] Synthesis and Crystal Structure of Mercury-Substituted Type-I Clathrates A8Hg4Sn42 (A = K, Rb, Cs)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 4 2008Andreas Kaltzoglou Abstract The mercury-substituted type-I clathrates A8Hg4Sn42,with A = K, Rb or Cs, were obtained by fusion of the pure elements at high temperatures. The crystal structures of the compounds were refined from single-crystal X-ray diffraction data. They crystallize in the space group Pmn (No. 223), Z = 1 with a = 12.1255(4) Å for K8Hg4Sn42 (1), a = 12.1838(4) Å for Rb8Hg4Sn42 (2) and a = 12.2130(4) Å for Cs8Hg4Sn42 (3). The 3D framework of four-bonded atoms defines two types of polyhedral cages of different size that are fully occupied by the alkali-metal atoms. All three compounds are considered as formally charge-balanced Zintl phases without any homogeneity range. Differential thermal analysis (DTA) indicates that the stability of the clathrates significantly depends on the size of the encaged cations. The thermal stability of the title compounds and the binary phases A8Sn44 (A = K, Rb, Cs) is discussed. Temperature-dependent magnetic measurements for compound 3 show also the expected diamagnetic behaviour. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Structural redetermination, thermal expansion and refractive indices of KLu(WO4)2JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2006M. C. Pujol The crystal structure of monoclinic KLu(WO4)2 (KLuW) crystals was determined at room temperature by using single-crystal X-ray diffraction data. The unit-cell parameters were a = 10.576,(7), b = 10.214,(7), c = 7.487,(2),Å, , = 130.68,(4)°, with Z = 4, in space group C2/c. The unit-cell parameters of KLu1,xYbx(WO4)2 were determined in relation to Yb concentration. Vickers micro-indentations were used to study the microhardness of KLuW. The linear thermal expansion tensor was determined and the principal axis with maximum thermal expansion ( = 16.72 × 10,6,K,1), , was located 13.51° from the c axis. The room-temperature optical tensor was studied in the near-infrared (NIR) and visible range. The principal optical axis with maximum refractive index (ng = 2.113), Ng, was located 18.5° from the c axis at 632.8,nm. Undoped and ytterbium-doped KLuW crystals were grown by the TSSG (top-seeded-solution growth) slow-cooling method. The crystals show {110}, {}, {010} and {310} faces that basically constitue the habit of the KLuW crystals. [source] Structure, crystal growth and physical anisotropy of KYb(WO4)2, a new laser matrixJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2002M. C. Pujol The crystal structure of monoclinic KYb(WO4)2 (KYbW) crystals has been refined (in space group C2/c) at room temperature by using single-crystal X-ray diffraction data. KYbW undoped crystals were grown by the TSSG (top-seeded-solution growth) slow-cooling method. The crystals show {110}, {11}, {010} and {310} faces, which basically define their habit. The linear thermal expansion tensor has been determined and the principal axis with maximum thermal expansion ( = 16.68 × 10,6,K,1), , was located 12° from the c axis. Its principal , and axes are [302], [010] and [106] directions, respectively, in the crystallographic system. The optical tensor has been studied at , = 632.8,nm at room temperature; two principal axes, Ng and Nm, are located in the ac plane, while the other, Np, is parallel to [010]. The principal axis with maximum refractive index (ng = 2.45), Ng, was located 19° from the c axis. [source] Structural study of monoclinic KGd(WO4)2 and effects of lanthanide substitutionJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2001M. C. Pujol The crystal structure of monoclinic KGd(WO4)2 (KGW) has been refined at room temperature by using single-crystal X-ray diffraction data. The unit-cell parameters are a = 10.652,(4), b = 10.374,(6), c = 7.582,(2),Å, , = 130.80,(2)°, with Z = 4, in space group C2/c. The linear thermal expansion tensor has been determined and the principal axes are [302], [010] and [106]. The principal axis with maximum thermal expansion ( = 23.44 × 10,6,K,1), , was located 12° from the c axis. Undoped crystals of KGW and crystals that were partially doped by Pr, Nd, Ho, Er, Tm and Yb were grown by the top-seeding-solution growth slow-cooling method. The effect of doping on the KGW structure was observed in the cell parameters and in morphological changes. The changes in parameters follow the changes in lanthanide ionic radii. The doped crystals show {021} and {21} faces in addition to the {110}, {11}, {010}, {130} and {310} faces which basically follow the habit of the undoped KGW crystals. The development of the faces is related to the number of the most important periodic bond chains parallel to them. [source] Synthesis and structure of new 5-(arylidene)-3-(4-methylbenzoyl)thiazolidine-2,4-dionesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2010Katarina M. Popov-Pergal The derivatives of 5-substituted-2,4-thiazolidinedione have a broad spectrum of biological activities. In this article, new 5-(arylidene)-3-(4-methylbenzoyl)thiayolidine-2,4-diones 3a,k, with arylidene groups such as 4-phenylbenzylidene 3a, 3,4-dimethoxybenzylidene 3b, 2-hydroxybenzylidene 3c, 4-ethoxybenzylidene 3d, 5-methyl-2-furfurylidene 3e, 4-dimethylaminobenzylidene 3f, 1-naphthylidene 3g, 3,4-methylenedioxybenzylidene 3h, 4-benzyloxybenzylidene 3i, benzylidene 3j, and 4-methoxybenzylidene 3k, were synthesized by direct acylation of alkali metal salts of 5-arylidene-2,4-thiazolidinediones with 4-methylbenzoylchloride. Their structures were confirmed by elemental analysis, IR, 1H NMR and MS spectroscopy. In addition, crystal structure of the compound 3d was determined using single-crystal X-ray diffraction data. J. Heterocyclic Chem., 2010. [source] Modulated crystal structure of incommensurate low tridymiteACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2009Heribert A. Graetsch The incommensurately modulated crystal structure of low SiO2 tridymite was refined based on single-crystal X-ray diffraction data in the superspace group Cc(,0,)0. The data set consists of 885 main reflections, 1751 first-order, 924 second-order and 119 third-order satellite reflections with I > 3,(I). The modulation is mainly made up from cooperative twistings of the rigid SiO4 tetrahedra. Two orders of displacement waves are used to describe the modulation of the Si atoms and three orders for the O atoms. The maximal amplitudes are ca 0.6,Å. O atoms bridging pairs of tetrahedra in cis and trans configurations show different positional modulation patterns. The anisotropic displacement parameters (ADPs) are also modulated. A correlation between ADP modulations and positional modulations was found. [source] Trans -cinnamic acid and coumarin-3-carboxylic acid: experimental charge-density studies to shed light on [2,+,2] cycloaddition reactionsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Judith A. K. Howard As part of an ongoing series of experimental charge-density investigations into the intra- and intermolecular interactions present in compounds which undergo solid-state [2,+,2] cycloaddition reactions, the charge-density analyses of trans -cinnamic acid and coumarin-3-carboxylic acid are reported. Thus, high-resolution single-crystal X-ray diffraction data were recorded at 100,K for trans -cinnamic acid (sin,,/,max = 1.03,Å,1) and coumarin-3-carboxylic acid (sin,,/,max = 1.19,Å,1). In addition to the anticipated O,H...O hydrogen bonds weak C,H...O interactions were identified in both structures along with very weak intermolecular interactions between pairs of molecules that undergo solid-state [2,+,2] cycloaddition reactions upon irradiation. [source] Disordered misfit [Ca2CoO3][CoO2]1.62 structure revisited via a new intrinsic modulationACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2008Hervé Muguerra The structure of the thermoelectric lamellar misfit cobalt oxide [Ca2CoO3][CoO2]1.62 was refined again using single-crystal X-ray diffraction data. A new commensurate intrinsic modulation was observed involving a modulation vector orthogonal to the misfit direction (,,0,,,). The five-dimensional superspace group is C2/m(1,0)(,0,)gm and the structure was solved using a commensurate approximation. A new model is given involving an occupation modulation of the split sites of the [CoO] layer. This [CoO] layer can be described by triple chains running along b. The residual disorder along b can then be explained by the assumption of a local ordering with two types of clusters: CoO2 and Co5O4. A powder neutron diffraction experiment confirmed the ordering evidenced by the single-crystal X-ray diffraction study, but was not sufficient by itself to deal with this double modulated scheme. The new intrinsic modulation is destroyed by partial metal substitutions in the [CoO] layer. The structural modifications of this layer directly influence the physical properties which are related to the electronic structure of the [CoO2] layers. [source] Al14Ba8La26.3Ru18Sr53.7O167: a variant of cubic perovskite with isolated RuO6 unitsACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2010F. J. Zúñiga The crystal structure of the title aluminium barium lanthanum ruthenium strontium oxide has been solved and refined using neutron powder diffraction to establish the parameters of the oxygen sublattice and then single-crystal X-ray diffraction data for the final refinement. The structure is a cubic modification of the perovskite ABO3 structure type. The refined composition is Ba0.167La0.548Sr1.118Ru0.377Al0.290O3.480, and with respect to the basic perovskite structure type it might be written as (Ba8La13.68Sr34.32)(Al13.92La12.64Ru18.08Sr19.36)O192,x, with x = 24.96. The metal atoms lie on special positions. The A -type sites are occupied by Ba, La and Sr. The Ba atoms are located in a regular cuboctahedral environment, whereas the La and Sr atoms share the same positions with an irregular coordination of O atoms. The B -type sites are divided between two different Wyckoff positions occupied by Ru/Al and La/Sr. Only Al and Ru occupy sites close to the ideal perovskite positions, while La and Sr move away from these positions toward the (111) planes with high Al content. The structure contains isolated RuO6 octahedra, which form tetrahedral substructural units. [source] CsAl(H2AsO4)2(HAsO4): a new monoclinic protonated arsenate with decorated kröhnkite-like chainsACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2007Uwe Kolitsch The crystal structure of hydrothermally synthesized caesium aluminium bis[dihydrogen arsenate(V)] hydrogen arsenate(V), CsAl(H2AsO4)2(HAsO4), was determined from single-crystal X-ray diffraction data collected at room temperature. The compound represents a new structure type that is characterized by decorated kröhnkite-like [100] chains of corner-sharing AlO6 octahedra and AsO4 tetrahedra. Ten-coordinated Cs atoms are situated between the chains, which are interconnected by five different hydrogen bonds [O,O = 2.569,(4),2.978,(4),Å]. All atoms are in general positions. CsAl(H2AsO4)2(HAsO4) is very closely related to CsGa(H1.5AsO4)2(H2AsO4) and isotypic CsCr(H1.5AsO4)2(H2AsO4). [source] | ||||||||||||||||||||||