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Cindy Dring Peter G. Jones 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(7):709-711
Bis(4‐picoline‐κN)gold(I) dibromidoaurate(I), [Au(C6H7N)2][AuBr2], (I), crystallizes in the monoclinic space group P21/n, with two half cations and one general anion in the asymmetric unit. The cations, located on centres of inversion, assemble to form chains parallel to the a axis, but there are no significant contacts between the cations. Cohesion is provided by flanking anions, which are connected to the cations by short Au...Au contacts and C—H...Br hydrogen bonds, and to each other by Br...Br contacts. The corresponding chloride derivative, [Au(C6H7N)2][AuCl2], (II), is isotypic. A previous structure determination of (II), reported in the space group P with very similar axis lengths to those of (I) [Lin et al. (2008). Inorg. Chem. 47 , 2543–2551], might be identical to the structure presented here, except that its γ angle of 88.79 (7)° seems to rule out a monoclinic cell. No phase transformation of (II) could be detected on the basis of data sets recorded at 100, 200 and 295 K. 相似文献
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Alexander Zhdanko Martin E. Maier 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(30):7894-7898
An experimental mechanistic study of the gold(I)‐catalyzed hydroamination shows the formation of conformationally flexible auro‐iminium salts Au‐Im , which originate from the protonation of a vinyl gold species. Rotation around the C CAu bond is the reason for the loss of stereospecificity of protodeauration, which explains the stereochemical result of the Stradiotto reaction. The ambiguity about inner or outer sphere mechanism is thus resolved in favor of the outer sphere mechanism. 相似文献
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Mechanistic Study of Gold(I)‐Catalyzed Hydroamination of Alkynes: Outer or Inner Sphere Mechanism? 下载免费PDF全文
Dipl.‐Chem. Alexander Zhdanko Prof. Dr. Martin E. Maier 《Angewandte Chemie (International ed. in English)》2014,53(30):7760-7764
An experimental mechanistic study of the gold(I)‐catalyzed hydroamination shows the formation of conformationally flexible auro‐iminium salts Au‐Im , which originate from the protonation of a vinyl gold species. Rotation around the C? CAu bond is the reason for the loss of stereospecificity of protodeauration, which explains the stereochemical result of the Stradiotto reaction. The ambiguity about inner or outer sphere mechanism is thus resolved in favor of the outer sphere mechanism. 相似文献
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Stanley A. Bajue Choy Lewis Karen Clarke Fitzgerald B. Bramwell Brian O. Patrick Carolyn Pratt Brock 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):m207-m211
The title complexes [μ‐(E)‐4,4′‐(ethene‐1,2‐diyl)dipyridine‐κ2N:N′]bis[halotris(4‐methylphenyl)tin(IV)], [Sn2(C7H7)6X2(C12H10N2)], where halo is chloro (X = Cl) and bromo (X = Br) are isostructural. In both crystals, the molecules lie on inversion centers, and there are voids of ca 80 Å3 that could, but apparently do not, accommodate water molecules. The corresponding iodo structure (X = I) is almost, but not quite, isostructural with the other two compounds; when Br is changed to I, the length of the c axis decreases by more than 1 Å and the voids are no longer large enough to accomodate any solvent molecule. The related complex [μ‐(E)‐4,4′‐(ethene‐1,2‐diyl)dipyridine‐κ2N:N′]bis[chlorotriphenyltin(IV)], [Sn2(C6H5)6Cl2(C12H10N2)], crystallizes in a related structure, but the molecules lie on general rather than on special positions. The molecular structures of the four complexes are similar, but the conformation of the phenyl derivative is approximately eclipsed rather than staggered. 相似文献
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A new and efficient synthesis of 2‐[1‐alkyl‐5,6‐bis(alkoxycarbonyl)‐1,2,3,4‐tetrahydro‐2‐oxopyridin‐3‐yl]acetic acid derivatives by a one‐pot three‐component reaction between primary amine, dialkyl acetylenedicarboxylate, and itaconic anhydride (=3,4‐dihydro‐3‐methylidenefuran‐2,5‐dione) is reported. The reaction was performed without catalyst and under solvent‐free conditions with excellent yields. Notably, the ready availability of the starting materials, and the high level of practicability of the reaction and workup make this approach an attractive complementary method to access to unknown 2‐[1‐alkyl‐5,6‐bis(alkoxycarbonyl)‐1,2,3,4‐tetrahydro‐2‐oxopyridin‐3‐yl]acetic acid derivatives. The structures were corroborated spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of domino Michael addition? cyclization reaction is proposed (Scheme 2). 相似文献
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Damian Mroz Ruimin Wang Ulli Englert Richard Dronskowski 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(6):591-597
1‐(Chloromethyl)‐3‐nitrobenzene, C7H6NClO2, and 1‐(bromomethyl)‐3‐nitrobenzene, C7H6NBrO2, were chosen as test compounds for benchmarking anisotropic displacement parameters (ADPs) calculated from first principles in the harmonic approximation. Crystals of these compounds are isomorphous, and theory predicted similar ADPs for both. In‐house diffraction experiments with Mo Kα radiation were in apparent contradiction to this theoretical result, with experimentally observed ADPs significantly larger for the bromo derivative. In contrast, the experimental and theoretical ADPs for the lighter congener matched reasonably well. As all usual quality indicators for both sets of experimental data were satisfactory, complementary diffraction experiments were performed at a synchrotron beamline with shorter wavelength. Refinements based on these intensity data gave very similar ADPs for both compounds and were thus in agreement with the earlier in‐house results for the chloro derivative and the predictions of theory. We speculate that strong absorption by the heavy halogen may be the reason for the observed discrepancy. 相似文献
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Anne Lechtken Detlef Schooss Jason R. Stairs Martine N. Blom Filipp Furche Nina Morgner Oleg Kostko Bernd von Issendorff Manfred M. Kappes 《ChemInform》2007,38(26):no-no
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. 相似文献
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Dr. Xiao-Li Pei Dr. Ana Pereira Dr. Ekaterina S. Smirnova Prof. Antonio M. Echavarren 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(32):7309-7313
Auration of o-trimethylsilyl arylphosphines leads to the formation of gold and gold–silver clusters with ortho-metalated phosphines displaying 3c–2e Au−C−M bonds (M=Au/Ag). Hexagold clusters [Au6L4](X)2 are obtained by reaction of (L−TMS)AuCl with AgX, whereas reaction with AgX and Ag2O leads to gold–silver clusters [Au4Ag2L4](X)2. Oxo-trigold(I) species [Au3O]+ were identified as the intermediates in the formation of the silver-doped clusters. Other [Au5], [Au4Ag], and [Au12Ag4] clusters were also obtained. Clusters containing PAu−Au−AuP structural motif display good catalytic activity in the activation of alkynes under homogeneous conditions. 相似文献
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2‐X‐1,3,2‐diazaarsolenes and 2‐X‐1,3,2‐ stibolenes (X = Cl, Br) were prepared from appropriate α‐amino‐aldimine precursors via transamination with ClSb(NMe2)2 or via base‐induced dehydrohalogenation with EX3 (E = As, Sb). The products were further converted into 2‐iodo‐derivatives via halide exchange with Me3SiI, or into 1,3,2‐diazaarsolenium or 1,3,2‐stibolenium salts via halide abstraction using E′X3 (E′ = Al, Ga, Sb) or Me3SiOTf. All compounds synthesized were characterized by spectroscopic data and several of them by single‐crystal X‐ray diffraction studies. The results of these investigations confirmed that diazaarsolenium or stibolenium cations are stabilized by similar π‐delocalization effects as the corresponding diazaphospholenium cations. 2‐Halogeno‐1,3,2‐diazaarsolenes and 2‐halogeno‐132‐stibolenes are best addressed as molecular species whose covalent E X bonds are as in 2‐chloro‐diazaphospholenes weakened by intramolecular π(C2N2) → σ*(E X) and, in the case of the Sb‐containing heterocycles, inter‐ molecular n(X′) → σ*(E X) hyperconjugation between the σ* (E X) orbital and a lone‐pair of electrons on the halogen atom of a neighboring molecule. Correlation of structural and spectroscopic data and the evaluation of halide transfer reactions allowed to conclude that the extent of E X bond weakening in the 2‐X‐substituted heterocycles decreases and thus the Lewis acidity of the cations increases, with increasing atomic number of the pnicogen atom. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:327–338, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20098 相似文献
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Richard Hoogenboom Mark A. M. Leenen Frank Wiesbrock Ulrich S. Schubert 《Macromolecular rapid communications》2005,26(22):1773-1778
Summary: Investigations regarding the cationic ring‐opening polymerization of 2‐phenyl‐2‐oxazoline under microwave irradiation and conventional heating are reported. This study was inspired by contradictory reports of the (non‐)existence of non‐thermal microwave effects that might accelerate the cationic ring‐opening of 2‐oxazolines. The polymerization of 2‐phenyl‐2‐oxazoline was investigated under pressure in acetonitrile and under reflux (or at the boiling point of butyronitrile in a closed vessel) in butyronitrile utilizing a single‐mode microwave reactor and automated synthesis robots with conventional heating.
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Rh2(OAc)4‐Catalyzed decomposition of diazo esters in the presence of perfluoroalkyl‐ or perfluoroaryl‐substituted silyl enol ethers smoothly provided the corresponding alkyl 2‐siloxycyclopropanecarboxylates in very good yields. The generated donor? acceptor cyclopropanes are equivalents of γ‐oxo esters, which we demonstrated by their one‐pot transformations to yield fluorine‐containing heterocycles. A reductive procedure selectively afforded perfluoroalkyl‐substituted γ‐hydroxy esters or γ‐lactones. The treatment of the donor? acceptor cyclopropanes with hydrazine or phenylhydrazine afforded a series of perfluoroalkyl‐ and perfluoroaryl‐substituted 4,5‐dihydropyridazin‐3(2H)‐ones. 相似文献
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C. Kohrt Dr. W. Baumann Dr. A. Spannenberg Dr. H.‐J. Drexler Prof. Dr. I. D. Gridnev Prof. Dr. D. Heller 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7443-7451
Recently described and fully characterized trinuclear rhodium‐hydride complexes [{Rh(PP*)H}3(μ2‐H)3(μ3‐H)][anion]2 have been investigated with respect to their formation and role under the conditions of asymmetric hydrogenation. Catalyst–substrate complexes with mac (methyl (Z)‐ N‐acetylaminocinnamate) ([Rh(tBu‐BisP*)(mac)]BF4, [Rh(Tangphos)(mac)]BF4, [Rh(Me‐BPE)(mac)]BF4, [Rh(DCPE)(mac)]BF4, [Rh(DCPB)(mac)]BF4), as well as rhodium‐hydride species, both mono‐([Rh(Tangphos)‐ H2(MeOH)2]BF4, [Rh(Me‐BPE)H2(MeOH)2]BF4), and dinuclear ([{Rh(DCPE)H}2(μ2‐H)3]BF4, [{Rh(DCPB)H}2(μ2‐H)3]BF4), are described. A plausible reaction sequence for the formation of the trinuclear rhodium‐hydride complexes is discussed. Evidence is provided that the presence of multinuclear rhodium‐hydride complexes should be taken into account when discussing the mechanism of rhodium‐promoted asymmetric hydrogenation. 相似文献
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