共查询到20条相似文献,搜索用时 15 毫秒
1.
Kerstin Schulze‐Matthi Jürgen Bendig Petra Neubauer Burkhard Ziemer 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(6):e257-e258
The bonding geometry of sulfur in the cations of the title compounds, C8H11S+·CF3SO3? and C13H13S+·CF3SO3?, respectively, is similar and is independent of the ratio of the Me/Ph substituents. As expected, in both cations, the S—Ph bonds are somewhat shorter than the S—Me bonds. In both crystal structures, the interaction between cations and anions is similar. 相似文献
2.
Russell G. Baughman Kenneth L. Martin Rajendra K. Singh James O. Stoffer 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(2):o103-o106
In 2,4‐dihydroxybenzaldehyde 2,4‐dinitrophenylhydrazone N,N‐dimethylformamide solvate {or 4‐[(2,4‐dinitrophenyl)hydrazonomethyl]benzene‐1,3‐diol N,N‐dimethylformamide solvate}, C13H10N4O6·C3H7NO, (X), 2,4‐dihydroxyacetophenone 2,4‐dinitrophenylhydrazone N,N‐dimethylformamide solvate (or 4‐{1‐[(2,4‐dinitrophenyl)hydrazono]ethyl}benzene‐1,3‐diol N,N‐dimethylformamide solvate), C14H12N4O6·C3H7NO, (XI), and 2,4‐dihydroxybenzophenone 2,4‐dinitrophenylhydrazone N,N‐dimethylacetamide solvate (or 4‐{[(2,4‐dinitrophenyl)hydrazono]phenylmethyl}benzene‐1,3‐diol N,N‐dimethylacetamide solvate), C19H14N4O6·C4H9NO, (XII), the molecules all lack a center of symmetry, crystallize in centrosymmetric space groups and have been observed to exhibit non‐linear optical activity. In each case, the hydrazone skeleton is fairly planar, facilitated by the presence of two intramolecular hydrogen bonds and some partial N—N double‐bond character. Each molecule is hydrogen bonded to one solvent molecule. 相似文献
3.
4.
Ming‐Liang Tong Shao‐Liang Zheng Xiao‐Ming Chen 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):960-962
The title compound, poly[[diaquadibromocadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐aquacadmium‐di‐μ‐bromo‐aquacadmium‐μ‐(1,3,5,7‐tetraazatricyclo[3.3.1.13,7]decane‐N1:N5)‐di‐μ‐bromo] dihydrate], [Cd3Br6(C6H12N4)2(H2O)4]·2H2O, is made up of two‐dimensional neutral rectangular coordination layers. Each rectangular subunit is enclosed by a pair of Cd3(μ2‐Br)6(H2O)3 fragments and a pair of (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragments as sides (hmt is hexamethylenetetramine). The unique CdII atom in the Cd2Br2 ring in the Cd3(μ2‐Br)6(H2O)3 fragment is in a slightly distorted octahedral CdNOBr4 geometry, surrounded by one hmt ligand [2.433 (5) Å], one aqua ligand [2.273 (4) Å] and four Br atoms [2.6409 (11)–3.0270 (14) Å]. The CdII atom in the (μ2‐hmt)Cd(H2O)2Br2(μ2‐hmt) fragment lies on an inversion center and is in a highly distorted octahedral CdN2O2Br2 geometry, surrounded by two trans‐related N atoms of two hmt ligands [2.479 (5) Å], two trans‐related aqua ligands [2.294 (4) Å] and two trans‐related Br atoms [2.6755 (12) Å]. Adjacent two‐dimensional coordination sheets are connected into a three‐dimensional network by hydrogen bonds involving lattice water molecules, and the aqua, bromo and hmt ligands belonging to different layers. 相似文献
5.
Y. Akishige H. Shigematsu T. Tojo H. Kawaji T. Atake 《Journal of Thermal Analysis and Calorimetry》2005,81(3):537-540
Summary Specific heats on the single crystals of Sr2Nb2O7, Sr2Ta2O7 and (Sr1-xBax)2Nb2O7 were measured in a wide temperature range of 2-600 K. Heat anomalies of a λ-type were observed at the incommensurate phase transition of TINC (=495 K) on Sr2Nb2O7 and at the super-lattice phase transition of TSL (=443 K) on Sr2Ta2O7; the transition enthalpies and the transition entropies were estimated. Furthermore, a small heat anomaly was observed at the low temperature ferroelectric phase transition of TLOW (=95 K) on Sr2Nb2O7. The transition temperature TLOW decreases with increasing Ba content x and it vanishes for samples of x>2%. 相似文献
6.
L. Abbas L. Bih A. Nadiri Y. El Amraoui H. Khemakhem D. Mezzane 《Journal of Thermal Analysis and Calorimetry》2007,90(2):453-458
Thermal and chemical durability studies of the phosphate glasses belonging to the binary MoO3-P2O5 and the ternary K2O-MoO3-P2O5 systems are reported. The chemical resistant attack tests carried out on the free alkaline MoO3-P2O5 glasses show that the glass associated with the P/Mo ratio 2 has the high chemical durability. It shows also a high glass
transition temperature value. The above findings are interpreted in terms of the cross-link density of the glasses and the
strength of the M-O bonds (M=P, Mo).
The influence of K2O addition on the properties (density, T
g, durability) of this binary high water resistant glass is studied. It is found that the chemical durability along with the
other physical properties are reduced by the incroporation of K2O in the glass matrix. The results were explained by assuming the formation of non-bridging oxygens and weak bonds. The mechanism
of the dissolution of these glasses is proposed. 相似文献
7.
Hiroki Akutsu Jun‐ichi Yamada Shin'ichi Nakatsuji 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(8):o433-o434
The title compound, C24H20P+·C9H17NO5S−, consists of an organic monovalent cation and an organic monovalent anion, the latter being derived from the TEMPO radical (TEMPO is 2,2,6,6‐tetramethylpiperidin‐1‐oxyl). Two inversion‐related anions interact via two –O—H⃛O—S– hydrogen bonds, forming a dimer in which there are no short contacts between the spin centres (–N—O) of the TEMPO(OH)SO3− anions. Furthermore, no significant magnetic interaction is observed between the dimers because the dimer is surrounded by cations. These results are consistent with the paramagnetic behaviour of the title salt. 相似文献
8.
John Nicolson Low George Ferguson James L. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e317-e317
In the title compound, [Sb(CH3)(C6H5)3]BF4, there are four independent cations and anions in the asymmetric unit. The geometry around the Sb atom is distorted tetrahedral, with Sb—C distances in the range 2.077 (4)–2.099 (10) Å and angles at the Sb atom in the range 103.3 (3)–119.0 (4)°. 相似文献
9.
Maren Pink Doyle Britton Wayland E. Noland Matthew J. Pinnow 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):1271-1273
The molecular structures of the title compounds, 2,4,6‐trichlorophenylisonitrile (IUPAC name: 2,4,6‐trichlorophenyl isocyanide), C7H2Cl3N, and 2,4,6‐trichlorobenzonitrile, C7H2Cl3N, are normal. The two structures are not isomorphous, but do contain similar two‐dimensional layers in which pairs of molecules are held together by pairs of Cl?CN [3.245 (3) Å] or Cl?NC [3.153 (2) Å] interactions. The two‐dimensional isomorphism is lost through different layer‐stacking modes. 相似文献
10.
9,10‐Diphenyl‐9,10‐epidioxyanthracene and 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol
Anwar Usman Hoong‐Kun Fun Yun Li Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):o308-o310
9,10‐Diphenyl‐9,10‐epidioxyanthracene, C26H18O2, (I), was accidentally used in a photooxygenation reaction that produced 9,10‐dihydro‐10,10‐dimethoxy‐9‐phenylanthracen‐9‐ol, C22H20O3, (II). In both compounds, the phenyl rings are approximately orthogonal to the anthracene moiety. The conformation of the anthracene moiety differs as a result of substitution. Intramolecular C—H⃛O interactions in (I) form two approximately planar S(5) rings in each of the two crystallographically independent molecules. The packing of (I) and (II) consists of molecular dimers stabilized by C—H⃛O interactions and of molecular chains stabilized by O—H⃛O interactions, respectively. 相似文献
11.
A. V. Egorysheva V. D. Volodin T. Milenov P. Rafailov V. M. Skorikov T. D. Dudkina 《Russian Journal of Inorganic Chemistry》2010,55(11):1810-1817
A physicochemical study of glasses based on the MO-Bi2O3-B2O3 and SrO-Bi2O3-B2O3 systems was performed. Glass formation regions were found. The structural and optical properties, as well as the thermal
behavior of the glasses, were studied. 相似文献
12.
Summary We have fabricated glasses in the Bi-2223 HTc superconductor system with Bi2Sr2Ca2Cu3-xErxO10+ δ nominal composition, where x=0.5 and 1.0, by the glass-ceramic technique. Using an analysis developed for non-isothermal crystallization studies, information on some aspects of crystallization temperature and thermal properties has been obtained. The crystallization studies were made using DTA with several uniform rates. The calculations of crystallization activation energies, Ea, and the Avrami parameters, n, were made based on the non-isothermal kinetic theory of Kissinger and the Ozawa’s equations. The DTA data of the samples showed that the first crystallization temperature, Tx1, increases and the second crystallization temperature, Tx2, decreases by increasing the Er concentration. This suggests that the Er substitution had significant effect on the glassification of the BSCCO material due to change on the surface nucleation and increased ionic activities at high temperature region. The activation energy for crystallization, Ea, of the samples was also showed an increase at high Er concentration case. However, the Avrami parameter, n, decreased from 2.5 to 1.7 for x=0.5 and 1.0 samples, respectively. This suggests that the growth mechanism is diffusion-controlled and three-dimensional parabolic growth takes place near the first crystallization temperature. The oxidization rates and the activation barrier for oxygen out-diffusion process, E, was calculated using the TG data. It was found that the total mass gain in the x=0.5 sample is comparably smaller than that of the x=1.0 sample. This shows that the oxygen absorption of the x=1.0 sample is faster than the x=0.5 sample, leading to increase in the oxidization rate in the x=1.0 material. 相似文献
13.
Jem‐Mau Lo Golam Mostafa Ling‐Yin Chang Fen‐Ling Liao Tian‐Huey Lu 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(4):o276-o277
The title compound, C10H18N2S2, acts as an important precursor for the synthesis of the pharmaceutically important diaminedithiol ligand system. The molecule has a local twofold axis and the arrangement of the S2N2 donor atoms in the macrocycle is anticlinal. 相似文献
14.
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):1015-1016
The whole molecule of the title compound, C19H14N4O2, is essentially planar, with a highly conjugated π system. In the crystal, the molecules are packed as chains along the [011] direction connected by O—H?N intermolecular hydrogen bonds. 相似文献
15.
Dianne D. Ellis Anthony L. Spek Pieter Imhoff Cornelis J. Elsevier 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(7):836-837
The cationic part of the homodifunctional aminophosphoranyl ligand, C41H41N2P2+·I?, shows interesting features associated with the N—P—C—P—N skeleton. The P—C(H) bond distances [1.696 (3) and 1.697 (3) Å] possess partial double‐bond characteristics. The nature of the P—C(H) and P—N bonds suggests that the positive charge is only distributed around the P—C—P atoms. The structure has near twofold symmetry through the central methylide‐C atom. 相似文献
16.
T. V. Gubanova E. I. Frolov I. K. Garkushin 《Russian Journal of Inorganic Chemistry》2007,52(12):1978-1981
Phase equilibria in the three-component systems LiBr-LiVO3-Li2MoO4 and LiBr-Li2SO4-Li2MoO4 have been studied using differential thermal analysis (DTA). Eutectic compositions have been determined (mol %): in the system LiBr-LiVO3-Li2MoO4, 56.0 LiBr, 22.0 LiVO3, and 22.0 Li2MoO4 with a melting temperature of 413°C; and in the system LiBr-Li2SO4-Li2MoO4, 65.0 LiBr, 14.0 Li2SO4, and 21.0 Li2MoO4 with a melting temperature of 421°C. Phase fields have been demarcated. 相似文献
17.
Zh. A. Kochkarov M. V. Khubaeva Z. L. Khakulov 《Russian Journal of Inorganic Chemistry》2011,56(5):783-786
This is the first study of the NaBO2-Na2CO3-Na2MoO4-Na2WO4 quaternary system by differential thermal analysis. Na2[MoO4(x)WO4(1 − x)] solid solutions in the quaternary system are found to not decompose. 相似文献
18.
Hai-Rong Guo Yuan Gao Ai-Dong Li Zhong Yan Di Wu 《Journal of Sol-Gel Science and Technology》2008,45(3):315-318
Pb0.56Sr0.44Zr0.52Ti0.48O3 (PSZT) inverse opal photonic crystals (PCs) have been synthesized by a process of self-assembly in combination with a sol–gel
procedure. PSZT inverse opals show pure perovskite structure with good orders in three dimensions. The evident photonic band
gaps have been observed in the transmittance spectra with a blue-shift phenomenon due to the decrease of opal template periods.
PSZT inverse opals also exhibit the reflection peaks in basic agreement with the calculated results. This three-dimensional
(3D) ordered PSZT inverse opals have shown interesting optical characteristics and potential applications in optoelectronic
and photonic devices. 相似文献
19.
Gang Xue Qi Fang Wentao Yu 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(11):o653-o655
4,5‐Propylenedithio‐1,3‐dithiole‐2‐thione, C6H6S5, (I), crystallizes in the centrosymmetric space group P21/c. The molecular packing is characterized by pairs of S⋯S intermolecular contacts between neighbouring molecules, which may account for the rather high thermal stablity of the crystal. 4,5‐Propylenedithio‐1,3‐dithiol‐2‐one, C6H6OS4, (II), in which an O atom replaces the terminal S atom of (I), crystallizes in the non‐centrosymmetric polar space group Cc. The packing pattern of (II) indicates that the macropolarization direction is along [101]. Although the packing patterns are qualitatively significantly different, the molecular structures of (I) and (II) are similar, each exhibiting a chair conformation. 相似文献
20.
Hiroyuki Hosomi Shigeru Ohba Hiromu Aoyama 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(4):e155-e155
The title compound, C19H21NS, is the photoproduct obtained from N‐isopropyl‐N‐[(E)‐2‐phenylpropenyl]thiobenzamide. Recrystallization showed a spontaneous resolution. 相似文献