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221.
Edm Thiele Theodor Posner E. Thon P. N. Raikow und Leo Glaser 《Fresenius' Journal of Analytical Chemistry》1904,43(10):637-638
Ohne Zusammenfassung 相似文献
222.
Kelley P Lin S Edouard G Day MW Agapie T 《Journal of the American Chemical Society》2012,134(12):5480-5483
Mechanistic studies of the hydrogenolysis of aryl ethers by nickel were undertaken with (diphosphine)aryl methyl ethers. A Ni(0) complex containing Ni-arene interactions adjacent to the aryl-O bond was isolated. Heating led to aryl-O bond activation and generation of a nickel aryl methoxide complex. Formal β-H elimination from this species produced a nickel aryl hydride which can undergo reductive elimination in the presence of formaldehyde to generate a carbon monoxide adduct of Ni(0). The reported complexes map out a plausible mechanism of aryl ether hydrogenolysis catalyzed by nickel. Investigations of a previously reported catalytic system using isotopically labeled substrates are consistent with the mechanism proposed in the stoichiometric system, involving β-H elimination from a nickel alkoxide rather than cleavage of the Ni-O bond by H(2). 相似文献
223.
A detailed analysis of the 35Cl/37Cl isotope effects observed in the 19.11 MHz 103Rh NMR resonances of [RhCln(H2O)6−n]3−n complexes (n = 3–6) in acidic solution at 292.1 K, shows that the ‘fine structure’ of each 103Rh resonance can be understood in terms of the unique isotopologue and in certain instances the isotopomer distribution in each complex. These 35Cl/37Cl isotope effects in the 103Rh NMR resonance of the [Rh35/37Cl6]3− species manifest only as a result of the statistically expected 35Cl/37Cl isotopologues, whereas for the aquated species such as for example [Rh35/37Cl5(H2O)]2−, cis-[Rh35/37Cl4(H2O)2]− as well as the mer-[Rh35/37Cl3(H2O)3] complexes, additional fine-structure due to the various possible isotopomers within each class of isotopologues, is visible. Of interest is the possibility of the direct identification of stereoisomers cis-[RhCl4(H2O)2]−, trans-[RhCl4(H2O)2]−, fac-[RhCl3(H2O)3] and mer-[RhCl3(H2O)3] based on the 103Rh NMR line shape, other than on the basis of their very similar δ(103Rh) chemical shift. The 103Rh NMR resonance structure thus serves as a novel and unique ‘NMR-fingerprint’ leading to the unambiguous assignment of [RhCln(H2O)6−n]3−n complexes (n = 3–6), without reliance on accurate δ(103Rh) chemical shifts. 相似文献
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225.
Zhongshu Li Xiaodan Chen Liu Leo Liu Moritz Theodor Scharnhlz Hansjrg Grützmacher 《Angewandte Chemie (International ed. in English)》2020,59(11):4288-4293
In contrast to cyclic π‐conjugated hydrocarbons, the coordination chemistry of inorganic heterocycles is less developed. Dicarbondiphosphides stabilized by N‐heterocyclic carbenes (NHCs) NHC→C2P2←NHC ( 1 a , b ) (NHC=IPr or SIPr) contain a four‐membered C2P2 ring with an aromatic 6π‐electron configuration. These heterocycles coordinate to a variety of complex fragments with metals from groups 6, 9, and 10, namely [M0(CO)3] (M=Cr, Mo), [CoI(CO)2]+, or [NiIIBr2], through an η4‐coordination mode, leading to complexes 2 a , b , 3 a , b , 5 a , b , and 6 a , b , respectively. These complexes were characterized by X‐ray diffraction methods using single crystals, IR spectroscopy, and DFT calculations. In combination these methods indicate that 1 a , b behave as exceptionally strong 6π‐electron donors. 相似文献
226.
The recent paper ‘Linear connectivity forces large complete bipartite minors’ by Böhme, Kawarabayashi, Maharry and Mohar relies on an extension of Robertson and Seymour?s structure theorem for graphs with a forbidden minor. We describe a more direct approach which uses just the original structure theorem. 相似文献
227.
Andreas Vernaleken Bernhard Schmidt Theodor W. Hänsch Ronald Holzwarth Peter Hommelhoff 《Applied physics. B, Lasers and optics》2014,117(1):33-39
Complementing an earlier report (Vernaleken et al. in Opt Exp 20:18387, 2012), we investigate the residual phase jitter of a carrier-envelope frequency stabilized Ti:sapphire oscillator when pumped by additional commercially available pump lasers that were not part of the first study. We find that all tested pump lasers allow stabilization of the oscillator with a residual rms phase noise (integrated between 2 Hz and 5 MHz) of less than 150 mrad despite their different design and properties. Possible sources of technical noise and their elimination for specific models are discussed. 相似文献
228.
Theodor D. Gurkov Peter A. Kralchevsky 《Journal of Dispersion Science and Technology》2013,34(6-7):609-623
First we review some recent studies devoted to the role of surface moments (torques) in the mechanics and thermodynamics of fluid interfaces of arbitrary shape. The presence of bending and torsion moments leads to a difference between the mechanical and thermodynamical surface tensions and shear stresses. Next we review recent results in the mechanics of thin liquid films and the transition region film-Plateau border. Line and transversal tensions are assigned as excesses on the contact line. The transversal tension accounts for the attractive forces in the transition zone. Experiments with floating bubbles show that the movement of the contact line can lead to non-equilibrium values of the line tension, which can be interpreted in terms of a plastic deformation. 相似文献
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