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Dr. Christian Hering‐Junghans Max Thomas Dr. Alexander Villinger Prof. Dr. Axel Schulz 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(18):6713-6717
This work describes the synthesis and full characterization of elusive chloropnictenium ion salts of the type [RAr*N(SiMe)ECl][A] (RAr*=2,6‐(CHPh2)‐4‐R‐C6H2, R=Me, tBu; E=Sb, Bi; A?=GaCl4, Al(OCH(CF3)2)4). In these species the cation is significantly stabilized by weak arene interactions to flanking phenyl groups of the RAr* moiety. In this context the bonding situation has been studied by computational means and the reactivity towards the Lewis base 4‐dimethylaminopyridine (dmap) was investigated. 相似文献
23.
Maksim Kulichenko Nikita Fedik Prof. Dr. Konstatin V. Bozhenko Prof. Dr. Alexander I. Boldyrev 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(20):5311-5315
Growing demands of material science and, in particular, in the field of nonlinear optics (NLO) encourage us to look for stable highly polarizable molecules with excess diffuse electrons. An unusual class of compounds called electrides comply with these requirements. Many attempts have been made, yet only few electrides have been synthesized as solids and none of them as molecular species. In this paper, a new theoretically designed molecular species with electride characteristics is reported. The idea of this molecular electride comes from the formation of electride-like features in the MgO crystal with defect F-centers. The geometry of the investigated molecule can be described as a Mg4O4 cube with one oxygen atom removed. In Mg4O3, two 3s electrons are pushed out from the inner area of the molecule forming a diffuse electride multicentered bond. Our calculations show that this electride-like cluster possesses a noticeably large first hyperpolarizability β=5733 au. At the same time, a complete cube Mg4O4 and Mg4O32+ without electride electron pair have much smaller β: 0 au and 741 au, respectively. This fact indicates the decisive role of the electride electron pair in NLO properties. Additionally, vertical detachment energies of isomers (VDE), excitation energies ΔE, polarizabilities α, and IR spectra were calculated. These properties, including β, are supposed to be observable experimentally and can serve as indirect evidence of the stable molecular electride formation. 相似文献
24.
Alexander Y. Galashev Konstantin P. Katin Mikhail M. Maslov 《Physics letters. A》2019,383(2-3):252-258
We present Morse parameters for the interaction of graphene and silicene surfaces with the atoms of practically important metals Ni, Ag, and Li. The parameters' values are derived from the dispersion corrected density functional calculations. Two possible cases of -hybridized C/Si atoms in the unbroken graphene/silicene sheets and sp-hybridized atoms near the vacancies are considered. Proposed Morse parameters' sets reproduce binding energies, bond lengths and oscillation frequencies of metal atoms adsorbed on the hollow positions over the rings of C60 and Si60 fullerenes. They also reproduce well the same quantities for the substituted C59M and Si59M fullerenes (M?=?Ni, Ag, Li). 相似文献
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Chemistry of Heterocyclic Compounds - Demethylation of methoxy groups in 6(8)-methoxy-2,4,5-tris(dimethylamino)quinolines with 48% HBr leads to nucleophilic substitution of the 4-NMe2 group with... 相似文献
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Mathematical Programming - The results on regularity behavior of solutions to variational inequalities over polyhedral sets proved in a series of papers by Robinson, Ralph and Dontchev-Rockafellar... 相似文献
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The growth-fragmentation equation describes a system of growing and dividing particles, and arises in models of cell division, protein polymerisation and even telecommunications protocols. Several important questions about the equation concern the asymptotic behaviour of solutions at large times: at what rate do they converge to zero or infinity, and what does the asymptotic profile of the solutions look like? Does the rescaled solution converge to its asymptotic profile at an exponential speed? These questions have traditionally been studied using analytic techniques such as entropy methods or splitting of operators. In this work, we present a probabilistic approach: we use a Feynman–Kac formula to relate the solution of the growth-fragmentation equation to the semigroup of a Markov process, and characterise the rate of decay or growth in terms of this process. We then identify the Malthus exponent and the asymptotic profile in terms of a related Markov process, and give a spectral interpretation in terms of the growth-fragmentation operator and its dual. 相似文献
30.
Vereshchagin Anatoly N. Karpenko Kirill A. Elinson Michail N. Minaeva Alexandra P. Goloveshkin Alexander S. Hansford Karl A. Egorov Mikhail P. 《Molecular diversity》2020,24(4):1327-1342
Molecular Diversity - A novel five-component diastereoselective synthesis of polysubstituted 2-piperidinones is reported. The Knoevenagel condensation–Michael addition–Mannich cascade... 相似文献