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We shall derive a new non-trivial upper bound for the dimensionof trace codes connected to algebraic-geometric codes. Furthermore,we shall deduce their true dimension if certain conditions aresatisfied. 相似文献
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Calero S Lobato MD García-Pérez E Mejías JA Lago S Vlugt TJ Maesen TL Smit B Dubbeldam D 《The journal of physical chemistry. B》2006,110(12):5838-5841
We have developed a computational framework for the adsorption of linear alkanes in protonated aluminosilicates. These zeolites contain trace amounts of water that form hydrated proton complexes. The presence of hydrated protons makes the simulations at the fully atomistic level difficult. Instead of constructing an elaborate and complex model, we show that an approach based on a coarse-graining of the proton-complex accurately describes the available experimental isotherms, Henry coefficients, heats of adsorption, and oxygen-proton distances. Our approach is supported by MP2 quantum mechanical simulations. The model gives remarkably good agreement with experimental data beyond the initial calibration set. 相似文献
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Dr. Marc Devillard Dr. Andreas Ehlers Dr. Maxime A. Siegler Dr. Ir. Jarl Ivar van der Vlugt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(15):3875-3883
Ligands with reactive carbon sites in the periphery of a metal center have emerged as a powerful approach for metal–ligand bond activation. These reactive carbon sites are commonly generated by deprotonation strategies. Carbon–silicon bond cleavage is a potential alternative to access such constructs. Herein, the monodesilylation of bis-silyl-substituted P,N scaffold PNSi2 in the coordination sphere of [RhI(Cl)(CO)( PNSi2 )] ( 1 ) with sodium azide is disclosed. This affords a unique dinucleating anionic κ2-C,N-κ1-P ligand with a carbanionic methine carbon atom directly bound to rhodium as part of a four-membered Rh-N-C-C rhodacycle. This dimer undergoes meta-pyridine C−H activation facilitated by weak bases, which leads to a desymmetrization of the system and provides a σ,π-bridging 3-pyridyl fragment bound to RhI. The facile Si−C cleavage strategy may pave the way to studying the reactivity and functionalization of a variety of κ2-C,N-coordinated pyridine scaffolds for selective transformations. 相似文献
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Redox‐Active‐Ligand‐Mediated Formation of an Acyclic Trinuclear Ruthenium Complex with Bridging Nitrido Ligands 下载免费PDF全文
Dr. Bidraha Bagh Daniël L. J. Broere Dr. Maxime A. Siegler Dr. Ir. Jarl Ivar van der Vlugt 《Angewandte Chemie (International ed. in English)》2016,55(29):8381-8385
Coordination of a redox‐active pyridine aminophenol ligand to RuII followed by aerobic oxidation generates two diamagnetic RuIII species [ 1 a (cis) and 1 b (trans)] with ligand‐centered radicals. The reaction of 1 a / 1 b with excess NaN3 under inert atmosphere resulted in the formation of a rare bis(nitrido)‐bridged trinuclear ruthenium complex with two nonlinear asymmetrical Ru‐N‐Ru fragments. The spontaneous reduction of the ligand centered radical in the parent 1 a / 1 b supports the oxidation of a nitride (N3?) to half an equivalent of N2. The trinuclear omplex is reactive toward TEMPO‐H, tin hydrides, thiols, and dihydrogen. 相似文献
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Gabriela Ionescu Jarl Ivar van der Vlugt Hendrikus C.L. Abbenhuis Dieter Vogt 《Tetrahedron: Asymmetry》2005,16(24):3970-3975
The synthesis of novel chiral tri- and bidentate phosphites 2, 5, 6 and 8, derived from incompletely condensed silsesquioxane backbones and binaphthol, is described. These compounds can be obtained in good yield and are characterized by multinuclear NMR spectroscopy, mass spectrometry and elemental analyses. The complexation with [Rh(cod)2]BF4 has been studied for all bidentate ligands. These nanosized ligands have been applied in the rhodium-catalyzed asymmetric hydroformylation of vinyl acetate and in the rhodium-catalyzed hydrogenation of methyl-(Z)-2-acetamidocinnamate. 相似文献
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A new force field for the simulation of the adsorption of cycloalkanes in nanoporous silica affords a significant improvement over any previously employed force field. The simulated isotherms reproduce the most salient features in the experimental isotherms extremely well. The study of cyclo-pentane, -hexane, and -heptane adsorption in MFI-type silica indicates an inflection for cyclopentane but not for cyclohexane at intermediate pressure. If corroborated by experiments, such an inflection point would afford an excellent calibration point for further force field developments. At low pressures, mixture isotherms of cyclohexane and n-hexane show a temperature dependence on the selectivity in accordance with recent results by J. P. Fox and S. P. Bates, J. Phys. Chem., 2004, 108, 17136. This dependence is caused by a difference in temperature dependence of the Henry coefficient for both molecules. At high pressures entropy effects due to packing always favor the sorption of n-hexane. Furthermore, the influence of the flexibility of the zeolite framework on the adsorption of these rather bulky molecules is investigated. It is found that this influence of the flexibility on the adsorption of cyclohexane is as small as with n-alkanes. 相似文献
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Dinuclear Palladium Complexes with Two Ligand‐Centered Radicals and a Single Bridging Ligand: Subtle Tuning of Magnetic Properties 下载免费PDF全文
M. Sc. Daniël L. J. Broere Dr. Serhiy Demeshko Prof. Dr. Bas de Bruin Dr. Evgeny A. Pidko Prof. Dr. Joost N. H. Reek Dr. Maxime A. Siegler Dr. Martin Lutz Dr. Jarl Ivar van der Vlugt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(15):5879-5886
The facile and tunable preparation of unique dinuclear [(L?)Pd?X?Pd(L?)] complexes (X=Cl or N3), bearing a ligand radical on each Pd, is disclosed, as well as their magnetochemistry in solution and solid state is reported. Chloride abstraction from [PdCl( NNOISQ )] ( NNOISQ =iminosemiquinonato) with TlPF6 results in an unusual monochlorido‐bridged dinuclear open‐shell diradical species, [{Pd( NNO ISQ)}2(μ‐Cl)]+, with an unusually small Pd‐Cl‐Pd angle (ca. 93°, determined by X‐ray). This suggests an intramolecular d8–d8 interaction, which is supported by DFT calculations. SQUID measurements indicate moderate antiferromagnetic spin exchange between the two ligand radicals and an overall singlet ground state in the solid state. VT EPR spectroscopy shows a transient signal corresponding to a triplet state between 20 and 60 K. Complex 2 reacts with PPh3 to generate [Pd(NNOISQ)(PPh3)]+ and one equivalent of [PdCl( NNOISQ )]. Reacting an 1:1 mixture of [PdCl( NNOISQ )] and [Pd(N3)( NNOI SQ)] furnishes the 1,1‐azido‐bridged dinuclear diradical [{Pd( NNO ISQ)}2(κ1‐N;μ‐N3]+, with a Pd‐N‐Pd angle close to 127° (X‐ray). Magnetic and EPR measurements indicate two independent S=1/2 spin carriers and no magnetic interaction in the solid state. The two diradical species both show no spin exchange in solution, likely because of unhindered rotation around the Pd?X?Pd core. This work demonstrates that a single bridging atom can induce subtle and tunable changes in structural and magnetic properties of novel dinuclear Pd complexes featuring two ligand‐based radicals. 相似文献