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1.
Hiroyuki Hosomi Shigeru Ohba Hiromu Aoyama 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(5):e221-e221
The crystal structure of the title thioamide, C21H23NOS, was determined to investigate the relationship between the photostability in the solid state and the structure. 相似文献
2.
Berislav Peri Biserka Koji‐Prodi 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):211-212
The structure of 4,4′‐dibromobenzophenone, C13H8Br2O, was determined at two different temperatures (293 and 103 K). A phase transition was not detected in this temperature range. Its crystal structure was found to be isostructural with that of the diiodo analogue, but not with the structure of the dichloro derivative. 相似文献
3.
Guang-hui Tian Cun-fang Liu Pu-hui Lai Hua Zhao Feng Nie 《Chemistry of Natural Compounds》2010,46(2):219-221
Taibaihenryiin T was isolated for the first time from Phlomis umbrosa Turcz, and its structure was elucidated on the basis of IR and NMR spectra analysis. Its molecular configuration, conformation,
and crystal structure were also characterized by X-ray structure analysis. The infrequency of the C–O–O–C group is manifested
in this molecular configuration, and hydrogen bonding assembles the molecules into a three-dimensional networking structure
in the crystal. 相似文献
4.
Bao-Lin Li Guang-hui Tian Zhen-guo Zhang Bo Liang Wei Wang 《Chemistry of Natural Compounds》2007,43(3):274-276
Hinokiol was isolated for the first time from Isodon henryi and the structure was elucidated on the basis of IR and NMR spectra analysis. Its molecular configuration, conformation,
and crystal structure were also characterized by X-ray structure analysis. The infrequent H-π stacking and hydrogen bonding assemble the molecules of hinokiol into a three-dimensional network structure.
Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 229–230, May–June, 2007. 相似文献
5.
Hiroyuki Hosomi Shigeru Ohba Hiromu Aoyama 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e154-e154
The crystal structure of the title thiobenzamide, C17H17NS, was determined to investigate the relationship between the photoreactivity in solid state and the structure. The geometry was confirmed to be the Z isomer. 相似文献
6.
The Ni@Si12 and Cu@Si12 clusters are studied in parallel within the framework of the density functional theory using the hybrid functional of Becke-Lee,
Parr and Yang (B3LYP), emphasizing the differences and similarities in structural and electronic properties. The dominant
structures for both clusters are a distorted hexagonal structure of Cs symmetry and a distorted octahedral structure of D2d. For Ni@Si12 the two structures are practically isonergetic whereas for Cu@Si12 the energy difference of the D2d structure from the lowest Cs structure of hexagonal origin is about 0.7 eV, at the B3LYP/TZVP level of theory. Contrary to Cu@Si12 for which the well known Frank–Kasper (FK) structure of C5v symmetry is a real local minimum of the energy hyper-surface (although higher by more than 1.6 eV from the global minimum),
for Ni@Si12 the FK structure is dynamically unstable. The HOMO-LUMO gaps, the binding energies per atom and the embedding energies for
Cu@Si12 clusters are smaller by 0.5, 0.1 and 1.1 eV, respectively compared to the Ni@Si12 clusters. This is attributed to different type of bonding in the two clusters. 相似文献
7.
Marcella Pani Angelo Mugnoli Enzo Sottofattori 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):840-842
In the crystal structure of C12H11ClO, the (planar) molecules give rise to a parallel packing. A model crystal obtained by semi‐empirical and packing‐energy calculations is consistent with the observed structure. 相似文献
8.
Mwaffak Rukiah Mahmoud Al‐Ktaifani 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(4):m170-m172
In order to investigate the effect of counter‐anions on the polymeric structure of (2,2‐dimethylpropane‐1,3‐diyl diisocyanide)silver(I) complexes, the novel title polymeric compound, [Ag(NO3)(C7H10N2)]n, has been synthesized. The crystal structure was determined by simulated annealing from X‐ray powder diffraction data collected at room temperature. The current structure is similar to the recently reported structure of the analogue with chloride replacing nitrate. This study illustrates that both the chloride and nitrate complexes crystallize in the orthorhombic system in the Pbca space group with one monomer in the asymmetric unit, and also gives a strong indication that the counter‐anion does not have a considerable effect on the polymeric structure of the complex. The Ag centre lies in a distorted tetrahedral environment and is bonded to two 2,2‐dimethylpropane‐1,3‐diyl diisocyanide ligands to form chains. The nitrate anions crosslink the Ag centres of the chains to form a two‐dimensional polymeric network structure. 相似文献
9.
Bhumasamudram Jagadish Michael D. Carducci Alice Dawson Gary S. Nichol Eugene A. Mash 《Acta Crystallographica. Section C, Structural Chemistry》2008,64(8):o431-o433
The title methanol solvate, C24H22N4O5·CH3OH, forms an extended three‐dimensional hydrogen‐bonded structure, assisted by the presence of several good donor and acceptor sites. It shows none of the crystal packing features typically expected of piperazinediones, such as amide‐to‐amide R22(8) hydrogen bonding. In this structure the methanol solvent appears to play only a space‐filling role; it is not involved in any hydrogen bonding and instead is disordered over several sites. This study reports, to the best of our knowledge, the first crystal structure of an indane‐containing piperazinedione compound which exhibits a three‐dimensional hydrogen‐bonded structure formed by classical (N—H...O and N—H...N) hydrogen‐bonding interactions. 相似文献
10.
John N. Low Justo Cobo Manuel Nogueras Adolfo Snchez Harlen Torres Braulio Insuasty 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(5):o298-o300
The supramolecular structure of the title compound, C19H15N3, is defined by π–π‐stacking and C—H?π interactions. There are no conventional hydrogen bonds in the structure. 相似文献
11.
The local and medium-range structure of the 20CaO·20Al2O3·60SiO2 glass generated by classical molecular dynamics simulations has been compared to NMR experiments by computing the 27Al and 17O NMR parameters and NMR spectra from first-principles simulations. The calculation of the NMR parameters (chemical shielding
and quadrupolar parameters), which are then used to simulate solid-state MAS and 3QMAS NMR spectra, is achieved by the gauge
including projector augmented-wave and the projector augmented-wave methods on the DFT-PBE relaxed structure. The NMR spectra
calculated with the present approach are found to be in excellent agreement with the experimental data, providing an unambiguous
view of the local and medium-range structure of aluminosilicate glasses. 相似文献
12.
A. A. Shutilov G. A. Zenkovets S. V. Tsybulya V. Yu. Gavrilov G. N. Kryukova 《Kinetics and Catalysis》2012,53(3):409-418
The effect of the microstructure of titanium dioxide on the structure, thermal stability, and catalytic properties of supported CuO/TiO2 and CuO/(CeO2-TiO2) catalysts in CO oxidation was studied. The formation of a nanocrystalline structure was found in the CuO/TiO2 catalysts calcined at 500°C. This nanocrystalline structure consisted of aggregated fine anatase particles about 10 nm in size and interblock boundaries between them, in which Cu2+ ions were stabilized. Heat treatment of this catalyst at 700°C led to a change in its microstructure with the formation of fine CuO particles 2.5–3 nm in size, which were strongly bound to the surface of TiO2 (anatase) with a regular well-ordered crystal structure. In the CuO/(CeO2-TiO2) catalysts, the nanocrystalline structure of anatase was thermally more stable than in the CuO/TiO2 catalyst, and it persisted up to 700°C. The study of the catalytic properties of the resulting catalysts showed that the CuO/(CeO2-TiO2) catalysts with the nanocrystalline structure of anatase were characterized by the high-est activity in CO oxidation to CO2. 相似文献
13.
A. Yu. Teterin M. V. Ryzhkov Yu. A. Teterin K. I. Maslakov T. Reich S. L. Molodtsov 《Journal of Structural Chemistry》2011,52(2):295-303
The structure of the resonant electron emission (REE) spectra of UO2 (REE appears under the excitation with synchrotron radiation near the O4,5(U) absorption edge at ∼100 eV and ∼110 eV) is studied with regard to the X-ray O4,5(U) absorption spectrum of UO2 and a quantitative scheme of molecular orbitals based on the X-ray electron spectroscopy data and the results of a relativistic
calculation of the electronic structure of UO2. The structure of the REE spectra of U3O8 and UO2+x
is studied for comparison, and the effect of the uranium chemical environment in oxides on it is found. The appearance of
such a structure reflects the processes of excitation and decay involving the U5d and electrons of the outer valence MOs (OVMOs,
from 0 to ∼13 eV) and inner valence MOs (IVMOs, from ∼13 eV to ∼35 eV) of the studied oxides. It is noted that REE spectra
show the partial density of states of U6p and U5f electrons. Based on the structure of REE spectra, it is revealed that U5f electrons directly participate (without losing the f nature) in the chemical bonding of uranium oxides and are delocalized within CMOs (in the middle of the band), which results
in the enhancement of the intensity of the REE spectra of CMO electrons during resonances. The U6d electrons are found to be localized near the bottom of the outer valence band and are observed in the REE spectra of the
studied oxides as a characteristic maximum at 10.8 eV. It is confirmed that U6p electrons are effectively involved in the formation of IVMOs, which leads to the appearance of the structure in the region
of IVMO electron energies during resonances. This structure depends on the chemical environment of uranium in the considered
oxides. 相似文献
14.
Carl Henrik Grbitz 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(11):o810-o812
The asymmetric unit in the crystal structure of the title compound, C15H22N2O3·0.88H2O, contains two peptide molecules with completely different conformations. The structure is divided into hydrophobic and hydrophilic layers, with channels of water molecules at the layer interface. 相似文献
15.
Frdrique Brgier Martin Brring Christian Kleeberg 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(4):o225-o227
In the crystal structure of the title compound, C8H11NO2, three distinct molecules are present in the asymmetric unit. The molecules are organized in two different hydrogen‐bonded tapes, which form a complex layered structure. A structural comparison with the crystal structures of related maleimide derivatives unravels a stepwise evolution of morphological complexity with increasing molecular complexity for this class of compounds. 相似文献
16.
Paul E. Kruger Philip R. Mackie Mark Nieuwenhuyzen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):e532-e532
The title compound, C6HCl3N2O4, is an intermediate in the synthesis of 1,3,5‐trichloro‐2,4,6‐trinitrobenzene. The crystal structure at 153 K shows no major deviations from the previously reported structure at 295 K other than the expected contraction of the a and c axes and, correspondingly, the β angle. 相似文献
17.
Yu. M. Basalaev Yu. N. Zhuravlev V. S. Permina A. S. Poplavnoi 《Journal of Structural Chemistry》2007,48(6):996-1000
The band structure spectra, densities of states, and valence and difference densities of LiPN2 and NaPN2 crystals were obtained by DFT self-consistent calculations using the nonlocal pseudopotentials and the localized pseudoorbital basis. Crystal-chemical analysis of these compounds shows that they occupy an intermediate position between the ideal structures of β-cristobalite and chalcopyrite, which manifests itself in the peculiarities of the electronic structure and chemical bonding. The valence band consists of three allowed subbands and differs radically from the typical valence band of chalcopyrite crystals in both subband structure and contributions of the s, p, and d atomic orbitals to the crystal orbitals. 相似文献
18.
Coexisting solid solutions with spinel and corundum structure were synthesized at 1773 K and two pressures, 1 bar and 25 kbar.
Samples were analyzed by electron microprobe analysis and X-ray powder diffraction.
Pressure and temperature were shown to affect the properties of the solid solutions in different ways. Pressure governs the
composition of the defect spinel Mg1−xAl2O4, and temperature changes the cation distribution between coexisting phases. This allows one to separate the effects of cation
exchange and magnetic contribution to the heat capacity in thermodynamic modeling. The defect spinel itself can form only
because γ-Al2O3 exists, polymorph with spinel structure. 相似文献
19.
S. Shanmuga Sundara Raj Hoong‐Kun Fun Zhong‐Lin Lu Wen Xiao Xiao‐Yang Gong Chang‐Ming Gen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):1013-1014
The crystal structure of the title compound, C15H14N2O2·H2O, is in the keto tautomeric form and the configuration at the azomethine C=N double bond is E. The molecule is non‐planar, with a dihedral angle of 27.3 (1)° between the aromatic rings. The crystal structure is stabilized by extensive hydrogen bonding involving the water molecule and hydrazone moiety. 相似文献
20.
Uwe‐Christoph Knig Michael Berkei Claudia Hirsch Hans Preut Terence Nigel Mitchell 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):e452-e453
The synthesis and X‐ray structure analysis of the title compound, [SnBr2(CH3)2(C4H9NO)2], are described. The crystal contains molecules which are separated by normal van der Waals distances. Organotin(IV) compounds are found in a variety of structural types, in which the Sn atom can, for example, be hexacoordinated. In this case, the preferred solid‐state molecular structure of the central atom is octahedral. The degree of distortion and the configuration depend on the ligands. 相似文献