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991.
Insights into the Halogen Oxidative Addition Reaction to Dinuclear Gold(I) Di(NHC) Complexes
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Dr. Marco Baron Prof. Cristina Tubaro Prof. Marino Basato Prof. Abdirisak Ahmed Isse Prof. Armando Gennaro Prof. Luigi Cavallo Prof. Claudia Graiff Prof. Alessandro Dolmella Dr. Laura Falivene Dr. Lucia Caporaso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10211-10224
Gold(I) dicarbene complexes [Au2(MeIm‐Y‐ImMe)2](PF6)2 (Y=CH2 ( 1 ), (CH2)2 ( 2 ), (CH2)4 ( 4 ), MeIm=1‐methylimidazol‐2‐ylidene) react with iodine to give the mixed‐valence complex [Au(MeIm‐CH2‐ImMe)2AuI2](PF6)2 ( 1 aI ) and the gold(III) complexes [Au2I4(MeIm‐Y‐ImMe)2](PF6)2 ( 2 cI and 4 cI ). Reaction of complexes 1 and 2 with an excess of ICl allows the isolation of the tetrachloro gold(III) complexes [Au2Cl4(MeIm‐CH2‐ImMe)2](PF6)2 ( 1 cCl ) and [Au2Cl4(MeIm‐(CH2)2‐ImMe)2](Cl)2 ( 2 cCl‐Cl ) (as main product); remarkably in the case of complex 2 , the X‐ray molecular structure of the crystals also shows the presence of I‐Au‐Cl mixed‐sphere coordination. The same type of coordination has been observed in the main product of the reaction of complexes 3 or 4 with ICl. The study of the reactivity towards the oxidative addition of halogens to a large series of dinuclear bis(dicarbene) gold(I) complexes has been extended and reviewed. The complexes react with Cl2, Br2 and I2 to give the successive formation of the mixed‐valence gold(I)/gold(III) n aX and gold(III) n cX (excluding compound 1 cI ) complexes. However, complex 3 affords with Cl2 and Br2 the gold(II) complex 3 bX [Au2X2(MeIm‐(CH2)3‐ImMe)2](PF6)2 (X=Cl, Br), which is the predominant species over compound 3 cX even in the presence of free halogen. The observed different relative stabilities of the oxidised complexes of compounds 1 and 3 have also been confirmed by DFT calculations. 相似文献
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Lepri Luciano Del Bubba Massimo Cincinelli Alessandra Boddi Laura 《平面色谱法杂志一现代薄层色谱法》2001,14(2):134-136
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
995.
Sandro Cacchi Cosmin L. Cotet Giovanni Forte Laura Martín Elies Molins Francesco Petrucci Adelina Vallribera 《Tetrahedron》2007,63(11):2519-2523
Electron-rich and electron-poor aryl iodides are converted, in high to excellent yields, into the corresponding carboxylic acids through a hydroxycarboxylation reaction catalyzed by a recoverable and reusable phosphine free palladium-carbon aerogel catalyst using lithium formate and acetic anhydride as an internal condensed source of carbon monoxide. The catalyst system can be reused several times without any appreciable loss of activity. 相似文献
996.
Adriana Isvoran Laura Pitulice Constantin T. Craescu Adrian Chiriac 《Chaos, solitons, and fractals》2008,35(5):960-966
The structures of EF-hand calcium binding proteins may be classified into two distinct groups: extended and compact structures. In this paper we studied 20 different structures of calcium binding proteins using the fractal analysis. Nine structures show extended shapes, one is semi-compact and the other 10 have compact shapes. Our study reveals different fractal characteristics for protein backbones belonging to different structural classes and these observations may be correlated to the physicochemical forces governing the protein folding. 相似文献
997.
Giovanni La Macchia Laura Gagliardi Geoffrey S. Carlson Ashley N. Jay Erik Davis Christopher J. Cramer 《Journal of Physical Organic Chemistry》2008,21(2):136-145
Values of σ and σ+, for use in linear free energy relationships, are determined for para hydrogen atoms having nuclear charges other than 1 (nucleomers). Hammett ρ values for a variety of free energies of activation, reaction, and other extrathermodynamic properties (e.g., vibrational frequencies) are computed therefrom and compared to those computed using typical para functional groups. The nucleomer correlations show excellent qualitative agreement with standard correlations but the quantitative agreement is less good, typically underestimating the standard ρ‐value by 10–60%. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Natalia Domracheva Anisoara Mirea Markus Schwoerer Laura Torre-Lorente Günter Lattermann 《Chemphyschem》2006,7(12):2567-2577
Copper(II) complexes formed by coordination of the Cu(II) ion with liquid-crystalline poly(propylene imine) dendrimer ligand (L) of the first (complex 1) and second (complex 2) generations with various Cu(II) contents (x = Cu/L) have been studied by electron paramagnetic resonance (EPR) spectroscopy. The existence of a redox-active blue complex 1 (x = 1.9) and the copper(II) nitrate electron transfer associated with the valence tautomerism are revealed for the first time in copper-based dendrimers. It has been shown that the electronic structure of the blue complex 1 (x = 1.9) is adequately described as a mixed-valence dimer containing d9- and diamagnetic d10-configurated copper ions, and an antiferromagnetically coupled NO3* radical arising on the nitrate-bridged counter ligand. The activation energy value found for the electron transfer is about 0.35 meV, which indicates a low-energy charge dynamic. The ability of the blue and green complexes 1 (x = 1.9) dissolved in isotropic solvents to orient themselves in the magnetic field was revealed by EPR spectroscopy. The degree of orientation of the molecular z axis (S(z)) of these complexes in the magnetic field differs, depending on the type of copper(II)-complexing site in the dendrimer ligand, and can reach 0.76, which is close to S(z) = 1 (completely aligned system). A combination of magnetic and orientational parameters indicates an NO4 environment of the Cu(II) ion in green complex 1 (x = 1.9), and confirms the chain structure with intermolecular Cu(II)-NO3-Cu(II) bridges between Cu(II) centres in columns. 相似文献