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Timo A. Kinder René Pior Dr. Sebastian Blomeyer Beate Neumann Dr. Hans-Georg Stammler Prof. Dr. Norbert W. Mitzel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(23):5899-5903
Chlorogermane (C2F5)3GeCl with very electronegative pentafluoroethyl groups was converted with LiCH2P(tBu)2 to obtain the intramolecular frustrated Lewis pair (FLP) (C2F5)3GeCH2P(tBu)2, a neutral, germanium-based FLP. Its reactivity was compared to its silicon homologue (C2F5)3SiCH2P(tBu)2. Both FLPs cleave NO but give cyclic (Si) and open-chain oxides (Ge). In reactions with HCl both FLPs gave the same adduct type in the solid state, while the proton seems more mobile in solution in the germanium case. Reactions with PhCNO and Me3SiCHN2 result in ring-type adducts. The structures of (C2F5)3GeCH2P(tBu)2 and of five adducts with substrates were elucidated by X-ray diffraction. The study clearly showed the germanium compound to have a more moderate Lewis acidity compared to the silicon analogue. 相似文献
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Reduced graphite oxide (RGO) is prospective for application as an active material for supercapacitor electrodes due to the simple synthesis, the high specific surface area and the presence of oxygen-containing functional groups. Functionalization of such materials affects hydrophilicity, surface morphology and contributes to the redox processes when potential is applied. In this article RGO was treatment by mixture of potassium hydroxide and chloroacetic acid; hydrobromic acid and oxalic acid; in various ratio of strong nitric, sulfuric and phosphoric acids. Such functionalization of RGO leads to decrease in particle size, increase the quantity of oxygen-containing groups on the surface of the materials and affects the change of carbon hybridization from sp2 to sp3. Furthermore, all the samples were investigated by cyclic voltammetry (CV) to study the redox processes occurring on the electrode material surface. The peaks on the CV curves were compared with the corresponding redox reversible reactions. Furthermore, the specific capacity of all samples was calculated. Thus, at low carboxylation level of RGO specific capacity is increased due to significant contribution of redox processes while high functionalization leads to decrease in conductivity and, as well in specific capacity. 相似文献
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Changguo Shao 《代数通讯》2020,48(4):1626-1631
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We consider random walk on the space of all upper triangular matrices with entries in which forms an important example of a nilpotent group. Peres and Sly proved tight bounds on the mixing time of this walk up to constants. It is well known that the column projection of this chain is the one dimensional East process. In this article we complement the Peres‐Sly result by proving a cutoff result for the mixing of finitely many columns in the upper triangular matrix walk at the same location as the East process of the same dimension. The proof is based on a recursive argument which uses a local version of a dual process appearing in a previous study, various combinatorial consequences of mixing and concentration results for the movement of the front in the one dimensional East process. 相似文献
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In this paper, we investigate the finite groups all of whose non-normal nilpotent subgroups are cyclic. We show that such groups are solvable with cyclic centers. If G is a non-supersolvable group, then G has only one non-cyclic Sylow subgroup which is either isomorphic to Q8 or is of type (q, q). 相似文献