共查询到20条相似文献,搜索用时 10 毫秒
1.
Stefanus Otto Alfred Johannes Muller 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1405-1407
The crystal structure of cis-[PtCl2(C6H15As)2], (I), is isostructural with a previously reported structure of cis-[PtCl2(C6H15P)2], (II). A new polymorph of (II) is also reported here. Selected geometrical parameters in the arsine complex are Pt—Cl 2.3412 (12) and 2.3498 (13), Pt—As 2.3563 (6) and 2.3630 (6) Å, Cl—Pt—Cl 88.74 (5), As—Pt—As 97.85 (2), and Cl—Pt—As 171.37 (4) and 177.45 (4)°. Corresponding parameters in the phosphine complex are Pt—Cl 2.364 (2) and 2.374 (2), Pt—P 2.264 (2) and 2.262 (2) Å, Cl—Pt—Cl 85.66 (9), P—Pt—P 98.39 (7), and Cl—Pt—P 170.26 (7) and 176.82 (8)°. 相似文献
2.
Dorothy H. Gibson Mark S. Mashuta Haiyang He 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(10):1135-1137
The two title compounds, [Re(C10H10N6)(CO)3]Br and [Re(C11H12N6)(CO)3]I·0.5C2H6O, have slightly distorted octahedral geometries about the rhenium centers. The distortions result from the constraints of the η3-coordinated tris(pyrazol-1-yl)methane ligands in each case which reduce the N—Re—N bond angles well below the preferred value of 90° for facially disposed ligands at a six-coordinate metal center. 相似文献
3.
Erik Heigel Hans Bock Volker Krenzel Mark Sievert 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):154-155
The title compound, Na+·C6H5S−·C6H16N2, forms lipophilically wrapped infinite sodium chains along the a axis. Each sodium cation is coordinated by three thiophenolate S atoms and two N centres of one tetramethylethylenediamine molecule. 相似文献
4.
Jun Lin Jun-Yong Zhang Yan Xu Xiao-Kang Ke Zijian Guo 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):192-194
The crystal structures of N,N′-(1,2-phenylene)bis(pyridine-2-carboxamide), C18H14N4O2, (I), and N,N′-(1,2-cyclohexanediyl)bis(pyridine-2-carboxamide) have been determined, the latter compound as the toluene hemisolvate, C18H20N4O2·0.5C7H8, (II). In (I), the benzene ring is nearly coplanar with one of the pyridine rings and forms a dihedral angle of 59.4 (1)° with the other. However, in (II), the dihedral angle of the two pyridine rings is 70.0 (1)°. 相似文献
5.
Jan Fábry Jan Kroupa Ivana Císařová 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):22-25
-Hexylammonium dihydrogenarsenate, (C6H16N)[AsO2(OH)2], and -octylammonium dihydrogenarsenate, (C8H20N)[AsO2(OH)2], are both ferroelastic at room temperature. The samples used in this study were not subjected to a phase transition after they had been crystallized. The structures are monoclinic (P21/n) and isostructural with the corresponding dihydrogenphosphates. Each sample contained two domains and each structure was refined as a twin. There are strong hydrogen bonds between dihydrogenarsenates and moderate hydrogen bonds between dihydrogenarsenates and -alkylammonium groups. The hydrogen-bond distances correspond well to those observed in the dihydrogenphosphates. All the atoms except two H atoms exist in pairs linked by the lost symmetry operations derived from the prototypic space group P2/b21/n21/a. Each of these two different H atoms is involved in an asymmetric hydrogen bond between an oxygen pair. These oxygens are supposed to change their roles as hydrogen-bond donors and acceptors during the ferroelastic switching. The phase-transition sequences are affected by interactions between the neighbouring organic chains in the structure. 相似文献
6.
Qingli Hao Fangfang Jian Xin Wang Ibrahim Abdul Razak S. Shanmuga Sundara Raj Hoong-Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):160-161
In the title compound, [Ni(C6H14O2PS2)2(C5H6N2)2], the coordination around the Ni atom, which lies on a crystallographic centre of symmetry, is octahedral with the S atoms from the dithiophosphate ligands occupying the equatorial positions, while the axial positions are occupied by the ring N atoms of the 2-aminopyridine ligands. The molecules form layers in the bc plane which are stacked in the direction of the a axis. 相似文献
7.
R. Alan Howie James L. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(9):1041-1043
The structures of the ketotins determined here, [SnCl2(C6H11O)2] and [Sn(C3S5)(C6H11O)2], respectively, along with that previously reported for [MeC(O)CH2CMe2]2SnI2, are compared with the structures of the analogous estertins [MeOC(O)CH2CH2]2SnX2. Pairwise comparison of the mean ketotin [estertin] Sn—X and Sn—O distances as Sn—X 2.4422 (4) [2.4054 (7) Å], 2.4970 (4) [2.471 (2) Å] and 2.8463 (4) [2.7788 (8) Å] and Sn—O 2.4926 (12) [2.528 (1) Å], 2.6110 (11) [2.629 (7) Å] and 2.435 (3) [2.525 (4) Å] (for X = Cl, S and I, respectively) clearly demonstrates the superior donor ability of the ketotin O atom in chelate formation. 相似文献
8.
Jiang Xia Wei-Yin Sun Yan Xu Kai-Bei Yu Wen-Xia Tang 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):38-39
The title molecule, [Ni(C6H17N3O)2](ClO4)2, possesses a crystallographic centre of symmetry at the NiII position. The coordination geometry around the NiII atom is distorted octahedral, consisting of six N atoms from two tripodal polyamine ligands, while the ethanol O atoms of the ligands remain uncoordinated. The crystal packing shows two-dimensional layers and an infinite three-dimensional framework which is stabilized by a hydrogen-bonded network. 相似文献
9.
Russian Journal of Organic Chemistry - Ullmann reaction of 2-[(6-chloroquinoxalin-2-yl)oxy]benzonitrile with 4-tert-butylphenol unexpectedly afforded... 相似文献
10.
Miao Du Xian-He Bu He Liu Xue-Bing Leng 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):201-202
The crystal structure of the title compound, C16H8N6, contains two independent molecules with no significant difference in their structures. The pyrazine ring makes dihedral angles of 36.7 (2) and 36.5 (3)° with the two pyridine rings in one molecule, and 43.1 (2) and 38.4 (1)° in the other. The dihedral angles between the two pyridine rings are 58.2 (2) and 56.0 (2)°, respectively. The favoured orientation of the pyridine rings is such that their N atoms face each other. 相似文献
11.
Jan W. Bats Marc A. Grundl A. Stephen K. Hashmi 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(2):208-210
The crystal structure of the title compound, C16H22N2O4, has two independent chiral molecules related by a pseudo-inversion centre. 14 of the 22 non-H atoms have a centrosymmetric counterpart within a tolerance of 0.17 Å. A search of the Cambridge Structural Database [Spring 2000; Allen & Kennard (1993). Chem. Des. Autom. News, 8 , 1, 31–37] shows at least 10% of the crystal structures reported in the literature with space group P21 and Z = 4 to be chiral compounds with a pseudo-P21/c packing. 相似文献
12.
A new strategy for the metal-free coordination–insertion ring-opening polymerization of tetrahydrofuran by the central metalloid Boron has been first identified. Bis(pentafluorophenyl)(phenoxy)borane was used as a catalyst for the polymerization reaction system. And polytetrahydrofuran with high molecular weight and narrow molecular weight distribution could be obtained. The proposed mechanism was studied by MALDI-TOF, ESI-MS and O-18 isotope labeling analyses as a metal-free coordination insert... 相似文献
13.
Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1434-1435
The asymmetric unit of the title compound, C9H14O3, consists of two molecules having conformations that differ by a rotation of 111.7 (5)° about the equatorial substituent bond, so that the side chains of the two species extend away from the ring in different directions. Each conformer forms centrosymmetric hydrogen-bonded acid-to-acid dimers with its own enantiomer [O⋯O = 2.681 (3) and 2.698 (4) Å]. There is an intermolecular C—H⋯O close contact involving the ketone group of one of the conformers. 相似文献
14.
Sofia Nikolaou Sérgio Hiroshi Toma Vagner Roberto de Souza Juliano B. Alves Koiti Araki Henrique Eisi Toma 《Transition Metal Chemistry》2011,36(7):775-783
The triruthenium carboxylate cluster [Ru3O(OAc)6(py)2(bpp)]+ (OAc = acetate) containing the bridging 1,3-bis(4-pyridyl)propane (bpp) ligand, and its dimeric species [{Ru3O(OAc)6(py2)}2(μ-bpp)]2+ were synthesized in order to investigate their inclusion compounds with β-cyclodextrin (β-CD). Characterization of the complexes
was carried out based on spectroscopic, electrochemical and spectroelectrochemical techniques, while the formation of inclusion
complexes was evaluated using 1H NMR/NOESY spectroscopy. Since bpp is a flexible ligand, a DFT study was carried out in order to characterize its conformational
isomers and their possible role in the host–guest chemistry with β-CD. Instead of observing the formation of inclusion compounds
with different stoichiometries, we observed the formation of 1:1 bpp/β-CD compounds in which the bpp ligand assumes different
conformations. The assembly of polymetallic rotaxane species was successfully demonstrated by monitoring the 1H NMR spectra of the monomeric cluster species in the presence of aquapentacyanoferrate(II) ions and β-CD. 相似文献
15.
Takafumi Yoshida Takayoshi Suzuki Sumio Kaizaki 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1274-1276
The complex cation in [4,5-dihydro-4,4,5,5-tetramethyl-2-(2-pyridyl-κN)imidazol-1-oxyl 3-oxide-κO3](nitrato-κ2O,O′)(N,N,N′,N′-tetramethyl-1,2-ethanediamine-κ2N,N′)nickel(II) hexafluorophosphate dichloromethane solvate, [Ni(NO3)(C6H16N2)(C12H16N3O2)]PF6·CH2Cl2, is the first example of a nitronyl nitroxide complex of a transition metal ion having d electrons in which nitrate is coordinated as a bidentate ligand. Owing to the smaller steric requirement of NO3−, the Ni—O(nitroxide) bond length [2.014 (2) Å] is remarkably shorter than that in the corresponding β-diketonate complexes [2.052 (4)–2.056 (2) Å]. 相似文献
16.
Type-III copper-containing enzymes have dicopper centers in their active sites and exhibit a novel capacity for activating aliphatic C-H bonds in various substrates by taking molecular oxygen. Dicopper enzyme models developed by Tolman and co-workers reveal exceptionally large kinetic isotope effects (KIEs) for the hydrogen transfer process, indicating a significant tunneling effect. In this work, we demonstrate that variational transition state theory allows accurate prediction of the KIEs and Arrhenius parameters for such model systems. This includes multidimensional tunneling based on state-of-the-art quantum-mechanical calculations of the minimum-energy path (MEP). The computational model of bis(μ-oxo)dicopper enzyme consists of 70 atoms, resulting in a 204-dimensional potential energy surface. The calculated values of E(a)(H) - E(a)(D), A(H)/A(D), and the KIE at 233 K are -1.86 kcal/mol, 0.51, and 28.1, respectively, for the isopropyl ligand system. These values agree very well with experimental values within the limits of experimental error. For the representative tunneling path (RTP) at 233 K, the pre- and post-tunneling configurations are 3.3 kcal/mol below the adiabatic energy maximum, where the hydrogen travels 0.54 ? by tunneling. We found that tunneling is very efficient for hydrogen transfer and that the RTP is very different from the MEP. It is mainly heavy atoms that move as the reaction proceeds from the reactant complex to the pretunneling configuration, and the hydrogen atom suddenly hops at that point. 相似文献
17.
18.
Qingli Hao Xujie Yang Fangfang Jian Lude Lu Xin Wang Ibrahim Abdul Razak Suchada Chantrapromma Hoong-Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):42-44
The two title compounds, [M(C6H14O2PS2)2(C12H8N2)], where M = CdII and FeII, are isomorphous. Each compound has a crystallographic twofold axis of symmetry through the metal atom and the 1,10-phenanthroline molecule. The central metal atom is coordinated to four S atoms from the two dithiophosphate groups and two N atoms from the 1,10-phenanthroline ligand. The environment of the metal atom is a distorted octahedron. 相似文献
19.
IntroductionRecentresearcheffortshavebeendevotedtothestudyoflatetransitionmetalcomplexesasmodelsystemsforthepolymerizationoroligomerizationofethylene .1 3ThemostnotableachievementshavebeendonebyBrookhart,4 Bennett,5andGibsongroups .6,7Theyinde pendentlyrepor… 相似文献
20.
Vincent M. Lynch Philip A. Gale Jonathan L. Sessler David Madeiros 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1426-1428
Crystals of the title complex, C28H36N4·C2H6OS, undergo a phase transition between room temperature and 198 K, as determined by X-ray diffraction techniques. A monoclinic form is observed at room temperature, while a triclinic modification is found at 198 K, with Z′ changing from 1 to 2. Differential scanning calorimetry (DSC) of the calixpyrrole–dimethyl sulfoxide complex revealed a series of phase changes between 273 and 243 K. The transition from the room-temperature monoclinic form to the low-temperature triclinic form is reversible, as determined by changes in the cell dimensions from remeasuring selected reflections at room temperature and at temperatures below 223 K. The uncomplexed calix[4]pyrrole molecule shows no phase changes occurring between room temperature and 233 K, the low-temperature limit of the DSC. 相似文献