共查询到20条相似文献,搜索用时 31 毫秒
1.
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
2.
Pierre Thuéry Martine Nierlich Jacques Vicens Bernardo Masci 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):70-71
The title compound, 7,13,21,27-tetra-tert-butyl-3,17-dioxapentacyclo[23.3.1.15,9.111,15.19,23]ditriaconta-1(29),5,7,9(30),11(31),12,14,19(32),20,22,25,27-dodecaene-29,30,31,32-tetraol, crystallizes as a solvate with one molecule of chloroform and one molecule of tetrahydrofuran, C46H60O6·CHCl3·C4H8O. The calixarene assumes a cone-like conformation stabilized by intramolecular hydrogen bonds involving both phenolic and ether O atoms. The two solvent molecules are located in each of the two half-cone cavities of the calixarene. 相似文献
3.
Geraldo L. Crossetti Carlos A. L. Filgueiras R. Alan Howie James L. Wardell Claudio M. Ziglio 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(11):1279-1281
In the title compound, [NiBr2(C31H32NP)], (I), the second reported example of a nickel–iminophosphine N,P-chelate in which the Ni atom has tetrahedral coordination, the Ni coordination is distorted as a consequence of the N—Ni—P chelate bite angle of 91.07 (6)° compensated by the Br—Ni—Br angle of 126.385 (18)°. In (I) and its analogue, viz. dichloro{[2-(4-isobutyloxazol-2-yl)phenyl]diphenylphosphine-N,P}nickel(II), the Ni—N and Ni—P distances are greater and the N—Ni—P ligand bite angles smaller than those observed in a series of related complexes with square-planar nickel. 相似文献
4.
ZHANG Xin-Li LI Zong-Xiao② 《结构化学》2006,25(9):1067-1070
1 INTRODUCTION Schiff base compounds have been of great interest for many years. These compounds are important systems in asymmetric catalysis and their transition metal complexes can often mimic biological sites, so they are of great significance as enzyme models. Their five- and six-coordinate complexes can disp- lay a variety of structural and magnetic properties. Complexes of d10 metal ion, such as cadmium (II), have aroused great attention since they are involved in many biological … 相似文献
5.
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
6.
7.
A low cost and accurate method for the detection and analytical determination of the activity of the enzyme α-l-fucosidase (AFU) was developed. The method was based upon measuring the fluorescence intensity of the complex ion associate of the ion associate of rhodamine-B and the compound 2-chloro-4-nitrophenol (RB+ CNP−) at 580 nm in phosphate buffer (pH 5) against the reagent blank. The influence of the different parameters, e.g. pH, incubation time, temperature, 2-chloro-4-nitrophenol concentration, foreign ions and surfactants that control the fluorescence intensity of the produced ion associate was critically investigated. The correlation between the fluorescence activity of the enzyme AFU by the developed procedures and the standard method was positive and highly significant in patients and controls (r2 = 0.99, p < 0.001). The developed method is simple and proceeds without practical artifacts compared to the standard method. 相似文献
8.
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
9.
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
10.
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
11.
Alexander J. Blake Vito Lippolis Simon Parsons Martin Schröder 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):36-37
In the title complex, [CuCl2(C12H24S6)]n, the CuCl2 unit and the ligand lie on and about inversion centres, respectively. The coordination geometry at CuII is a tetragonally elongated octahedron with the equatorial positions occupied by two chlorides, Cu—Cl 2.2786 (12) Å, and two S donors, Cu—S 2.3710 (13) Å. The apical positions of the octahedron are defined by two S donors at distances of 2.8261 (14) Å from the metal. The macrocyclic ligand adopts a very puckered and distorted conformation. Eight of the 18 torsion angles are less than 90° and all S-donors are oriented exo to the ring. 相似文献
12.
Robert W. Janes Brian S. Potter Matthew A. Naylor Amanda C. Ferguson Kantilal B. Patel Michael R. L. Stratford Peter Wardman Steven A. Everett 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(1):58-61
1-Methylindole-3-carboxaldehyde oxime, C10H10N2O, (I),and (E)-5-methoxy-1-methylindole-3-carboxaldehyde oxime, C11H12N2O2, (II), were examined structurally to ascertain the geometry of the hydroxyimino function relative to the indole core. Oxime (I) exhibits cis geometry and there are two molecules in the asymmetric unit. In contrast, oxime (II) exhibits trans geometry and has four molecules in the asymmetric unit, with the geometry of the 5-methoxy group in one molecule differing from that in the other three. Both crystal structures are maintained by hydrogen bonding with no π-stacking of the indole moiety present. 相似文献
13.
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
14.
L. N. Khripkova L. V. Kuritsyn N. V. Kalinina A. I. Sadovnikov 《Russian Journal of General Chemistry》2004,74(10):1543-1546
Kinetics of N-acylation of glycine, L--alanine, L-valine, L-leucine, and DL-isoleucine with 4-nitrophenyl benzoate in a water-2-propanol solvent at various temperatures were studied. The activation energy, enthalpy, and entropy of the process were determined. Correlations of the N-acylation rate constants of the -amino acids with the composition of the binary solvent at various temperatures were established, and the N-acylation rate constants of the -amino acids in water were determined.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 10, 2004, pp. 1665–1668.Original Russian Text Copyright © 2004 by Khripkova, Kuritsyn, Kalinina, Sadovnikov.This revised version was published online in April 2005 with a corrected cover date. 相似文献
15.
Anwar Usman Suchada Chantrapromma Hoong-Kun Fun 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1443-1446
The title compound, 3,5,7-triaza-1-azoniatricyclo[3.3.1.13,7]decane 2,4-dinitrophenolate monohydrate, C6H13N4+·C6H3N2O5−·H2O, the 1:1 hydrate adduct of hexamethylenetetramine (HMT) and 2,4-dinitrophenol, undergoes a temperature phase transition. In the room-temperature phase, the adduct crystallizes in the monoclinic P21/m space group, whereas in the low-temperature phase, the adduct crystallizes in the triclinic P space group. This phase transition is reversible, with the transition temperature at 273 K, and the phase transition is governed by hydrogen bonds and weak interactions. In both these temperature-dependent polymorphs, the crystal structure is alternately layered with sheets of hexamethylenetetramine and sheets of dinitrophenol stacked along the c axis. The hexamethylenetetramine and dinitrophenol moieties are linked by intermolecular hydrogen bonds. The water molecule in the adduct plays an important role, forming O—H⋯O hydrogen bonds which, together with C—H⋯O hydrogen bonds, bridge the adducts into molecular ribbons. Extra hydrogen bonds and weak interactions exist for the low-temperature polymorph and these interconnect the molecular ribbons into a three-dimensional packing structure. Also in these two temperature-dependent polymorphs, dinitrophenol acts as a hydrogen-bond acceptor and HMT acts as a hydrogen-bond donor. 相似文献
16.
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
17.
《Tetrahedron letters》1987,28(20):2277-2280
The nitro groups of α-nitro or β-nitro sulfides are replaced by hydrogen on treatment with triethylsilane in the presence of a Lewis acid. 相似文献
18.
Robert A. Burrow David H. Farrar Alan J. Lough Márcia R. Siqueira Fatima Squizani 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(8):e357-e358
The crystal structure of the title compound, C6H7O2P, shows continuous hydrogen-bonding chains in the x direction, with a P—O⋯O=P distance of 2.513 (3) Å. 相似文献
19.
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