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41.
Dr. Janis V. Musso Vincent Gramm Sarjano Stein Dr. Wolfgang Frey Prof. Dr. Michael R. Buchmeiser 《欧洲无机化学杂志》2023,26(3):e202200649
A series of molybdenum alkylidyne silyloxy N-heterocyclic carbene (NHC) complexes of the general formula [Mo(≡C(R))(OSiPh3)3(NHC)] (R=tBu, 4-methoxyphenyl, 2,4,6-trimethylphenyl; NHC = 1,3-diisopropylimidazol-2-ylidene, 1,3-dicyclohexylimidazol-2-ylidene, 1,3-dicyclohexyl-4,5-dihydroimidazol-2-ylidene, 1,3-dimethylimidazol-2-ylidene, 1,3-dimethyl-4,5-dichloroimidazol-2-ylidene) was synthesized. Single crystal X-ray analyses revealed that with increasing steric demand of the alkylidyne group, enhanced air-stability of the complexes in the solid-state is achieved with the most stable complex (R=2,4,6-trimethylphenyl, NHC = 1,3-diisopropylimidazol-2-ylidene) being stable in air for 24 h without showing signs of decomposition in 1H NMR. In contrast to previously reported air-stable molybdenum-based complexes, the novel catalysts proved to be highly active in alkyne metathesis, allowing for turnover numbers (TONs) of up to 6000 without further activation, and tolerant towards several functional groups such as tosyl, ether, ester, thioether and nitro moieties. Their air stability allows for facile handling of the catalysts in air and even after exposure to ambient atmosphere for one week, the most stable representative still displayed high productivity in alkyne metathesis. 相似文献
42.
J. Kaupužs R. V.N. Melnik J. Rimshans 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(4):363-370
Monte Carlo simulations of magnetization and susceptibility in the 3D XY
model are performed for system sizes up to L=384 (significantly exceeding the
largest size L=160 considered in work published previously), and fields h
≥ 0.0003125 at two different coupling constants β=0.5, and
β=0.55 in the ordered phase. We examine the prediction of the standard
theory that the longitudinal susceptibility χ∥ has a Goldstone mode singularity
such that χ∥ ∝h-1/2 holds when h↦0. Most
of our results, however, support another theoretical prediction that the
singularity is of a more general form χ∥ ∝hρ-1,
where 1/2<ρ<1 is a universal exponent related to the ∼hρ
variation of the magnetization. 相似文献
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Elda Markovic Kim Nguyen Stephen Clarke Kristina Constantopoulos Janis Matisons George P. Simon 《Journal of polymer science. Part A, Polymer chemistry》2013,51(23):5038-5045
A series of polyurethane hybrid networks have been synthesized using octakis(m‐isoprenyl‐α,α′‐dimethylbenzylisocyanato dimethylsiloxy) octasilsesquioxane (Q8M8TMI) as a crosslinking agent. The formation of the urethane linkages within the polyurethane hybrids was confirmed by photoacoustic FTIR spectroscopy. The TGA and DSC studies demonstrated that the incorporation of the POSS crosslinking agents altered the thermal properties of the polyurethanes, and that this was dependent on the length of the polyethylene glycol chain. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 5038–5045 相似文献
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Christoph Bolli Janis Derendorf Prof. Dr. Carsten Jenne Dr. Harald Scherer Christian P. Sindlinger Bianca Wegener 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13783-13792
The weakly coordinating anion [Me3NB12Cl11]? has been prepared by a simple two‐step procedure. The anion [Me3NB12Cl11]? is easily obtained in batches of up to 20 g by chlorination of the known [H3NB12H11]? anion with SbCl5 at about 190 °C and subsequent N‐methylation with methyl iodide. Starting from Na[Me3NB12Cl11], several synthetically useful salts with reactive cations ([NO]+, [Ph3C]+, and [(Et3Si)2H]+) were prepared. Full spectroscopic (NMR, IR, Raman, TGA, MS) characterization and single‐crystal X‐ray diffraction studies confirmed the identity and purity of the products. The thermal, chemical, and electrochemical stability as well as the basicity of the [Me3NB12Cl11]? anion is similar to that of the structurally related weakly coordinating 1‐carba‐closo‐dodecaborate and closo‐dodecaborate anions. The facile preparation of the [Me3NB12Cl11]? anion and its ideal chemical and physical properties make it a cheap alternative to other classes of weakly coordinating anions. 相似文献
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A mild and general route for preparing 2-pyridones from isocyanates and diynes is described. Ni imidazolyidene complexes were used to mediate cyclizations between both internal and terminal diynes with aryl and alkyl isocyanates. In addition, the efficacy of this protocol allows for the preparation of a fused seven-membered pyridone and for three component cyclizations. 相似文献