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71.
A density functional study of exchange coupling in halo-bridged dinuclear copper(II) compounds has been carried out. Coupling constants calculated for full unmodeled structures, as determined by X-ray diffraction, are in excellent agreement with experimental data, confirming the ability of the computational strategy used in this work to predict the magnetic behavior of such compounds. Model calculations have been used to examine the influence of several factors on the coupling constant: the nature of the bridging and terminal ligands, the coordination environment around copper atoms, and some structural distortions frequently found in this family of complexes. A ferromagnetic coupling is predicted when N-donor terminal ligands are present, especially for bromo-bridged systems, an interesting synthetic target. 相似文献
72.
Hydrogen bonding between early and late transition metal complexes is proposed as a strategy to obtain ferromagnetic interactions based on a theoretical study using density functional calculations. 相似文献
73.
Becerril J Burguete MI Escuder B Luis SV Miravet JF Querol M 《Chemical communications (Cambridge, England)》2002,(7):738-739
L-Valine containing cyclophanes have been shown to gelate organic solvents leading to soft materials with a clear expression of their chirality at the supramolecular level. 相似文献
74.
Burguete MI García-Verdugo E Vicent MJ Luis SV Pennemann H Graf von KN Martens J 《Organic letters》2002,4(22):3947-3950
[formula: see text] Polymeric monoliths 10 containing an amino alcohol moiety derived from an industrial waste material represent one of the best ligands for the enantioselective catalytic addition of ZnEt2 to benzaldehyde (99% ee), being recoverable and usable under flow conditions. 相似文献
75.
Barluenga J Aznar F Gutiérrez I García-Granda S Llorca-Baragaño MA 《Organic letters》2002,4(24):4273-4276
[reaction: see text] The first cyclopropanation reaction of olefins with Fischer dialkylaminocarbene complexes is presented. The reaction yields 1-aminocyclopropanecarboxylic acid derivatives in a single step, usually with high diastereoselectivity. An approach to the asymmetric version of this reaction is also presented. The synthetic utility of the procedure is exemplified by the synthesis of both cycles of metanoproline in a single step. In addition, the synthesis of the first Fischer carbene containing a halocarbonyl group is reported. 相似文献
76.
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78.
This paper describes a flow-injection (FI) method for the simultaneous determination of aniline and cyclohexylamine impurities in cyclamate products. The method consists of the derivatization of amines with 1,2-naphthoquinone-4-sulfonate under selective and non-selective conditions. Here, the selectivity is achieved by working at 20 degree C, at which only aniline reacts, whilst higher temperatures (80 degree C) lead to a non-selective reaction of the two analytes. The FI manifold is composed of two flow cells for the spectrophotometric detection of derivatives at 480 nm. Experimental conditions have been optimized by factorial design and multicriteria making approach. Quantification is accomplished by differential analysis of the analyte contributions in the double peaks generated when the sample reaches cell 1 and cell 2. Results obtained with the proposed method are in satisfactory agreement with those provided by the standard method for the analysis of cyclamate samples. 相似文献
79.
A novel organic-inorganic hybrid based on a dinuclear copper complex supported on a keggin polyoxometalate 总被引:1,自引:0,他引:1
Reinoso S Vitoria P Lezama L Luque A Gutiérrez-Zorrilla JM 《Inorganic chemistry》2003,42(12):3709-3711
The autoassembly process of copper-oxalate dimers and Keggin type polyoxometalates leads to the first example of a new family of organic-inorganic hybrids, K(14)[(Cu(2)(bpy)(2)(mu-ox))(SiW(11)O(39)Cu(H(2)O))](2)[SiW(11)O(39)Cu(H(2)O)]. approximately 55H(2)O. This compound crystallizes in the monoclinic space group C2/m, a = 37.932(6) A, b = 21.303(3) A, c = 12.546(2) A, beta = 106.16(1) degrees, Z = 2. The crystal structure reveals the presence of a polymeric hybrid built up of alternating dimer and polyoxometalate entities. 相似文献
80.