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ZuoWei Xie 《中国科学:化学(英文版)》2014,57(8):1061-1063
<正>Carboranes are a class of boron hydride clusters in which one or more of the BH vertices are replaced by CH units.Unlike small boranes, carboranes are kinetically and thermodynamically very stable as well as relatively chemically inert, which are often called three-dimensional relatives of benzenes. They are finding many applications in medicine as boron neutron capture therapy(BNCT) agents, in nanomaterials/supramolecular design as building blocks, and as ligands for transition metals [1]. However, their unique structures make derivatization difficult, which limits their application scope. To this end, there is a need to develop 相似文献
2.
碳硼烷和碳硼炔金属配合物中的金属-碳键具有不同于经典金属-碳键的化学性质.一方面,二十面体碳硼烷独特的电子和空间效应使得碳硼烷金属配合物中的金属-碳键不参与和不饱和分子的反应 另一方面,在一定条件下具有大空间位阻的碳硼笼可以诱导某些碳-碳偶联反应.然而,碳硼炔金属配合物中的金属-碳键能与多种不饱和分子发生反应,其反应模式取决于中心金属离子的电子构型.本文简要总结了我们近期在这方面的研究进展. 相似文献
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Transmetalation of carborane-fused zirconacycles to Cu(Ⅱ) induces the C-C coupling reaction to form four-membered rings. This serves as a new efficient and general methodology for the generation of a series of carborane-fused cyclobutenes and cyclobutanes. A reaction mechanism involving transmetalation to Cu(Ⅱ) and reductive elimination is proposed. 相似文献
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Density functional theory (DFT) combined with conductor-like solvent model (COSMO) have been performed to study the solvent effects of H2 adsorption on Cu(h k l) surface. The result shows H2 can not be parallel adsorbed on Cu(h k l) surface in gas phase and only vertical adsorbed. At this moment, the binding energies are small and H2 orientation with respect to Cu(h k l) surfaces is not a determining parameter. In liquid paraffin, when H2 adsorbs vertically on Cu(h k l) surface, solvent effects not only influences the adsorptive stability, but also improves the ability of H2 activation; When H2 vertical adsorption on Cu(h k l) surface at 1/4 and 1/2 coverage, H-H bond is broken by solvent effects. However, no stable structures at 3/4 and 1 ML coverage are found, indicating that it is impossible to get H2 parallel adsorption on Cu(h k l) surfaces at 3/4 and 1 ML coverages due to the repulsion between adsorbed H2 molecules. 相似文献
5.
ZhiWei Men XiuPing Sun WenHui Fang ZuoWei Li Biao Cao ShuQin Gao GuoHui Lu 《中国科学G辑(英文版)》2009,52(4):529-533
β-carotene with double fluorescence characteristics and large third-order optical nonlinearities, which is dissolved in the
carbon disulfide (CS2) as the core medium of a liquid core optical fiber (LCOF), is applied in the study of the CS2 stimulated Raman scattering (SRS). The results of this study show that when the concentrations of solution are more than
3.72×10−7 mol/L, the amplified spontaneous emission (ASE) of β-carotene is the main factor influencing the threshold and intensity
of Stokes lines; when the concentrations of solution are lower than 3.72×10−7 mol/L, the ASE disappears and the fluorescence plays the key role: The high-order Stokes lines may be observed at very low
input-laser power, and the Stokes thresholds decrease as the solution concentration increases. The result may be widely used
in the study of broadband stimulated radiation laser and seeding laser.
Supported by the National Natural Science Foundation of China (Grant No. 10774057) 相似文献
6.
ZuoWei Xie 《中国科学:化学(英文版)》2014,57(8):1058-1058
<正>As one of the most important five-member heterocyclic aromatic rings, pyrrole is widely distributed in numerous natural products and pharmaceutical agents. Asymmetric dearomatization of pyrroles is very attractive in organic synthesis given the fact that highly functionalized chira pyrrolines and pyrrolidines could be easily accessed from the readily available pyrroles. However, the reported asymmetric dearomatization reactions of pyrroles are limited to transition-metal-catalyzed [4+3] cycloaddition and hydrogenation reactions. The enantioselective intermolecular alkylative dearomatization of pyrroles is rare and challenging due to multiple selectivity issues including the 相似文献
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Reaction of [η 5:σ-Me2C(C5H4)(C2B10H10)]Ru(NCCH3)2 (1) with R1C≡CR1(R1 = Et, Ph) in toluene at 80°C yielded organoruthenium cyclobutadiene complexes [η 5:σ-Me2C(C5H4)(C2B10H10)]Ru(η 4-C4R 4 1 ) in >80% yield. Treatment of 1 with diynes R2C≡C(CH2)3C≡CR2 (R2 = Me, Et) in toluene at room temperature yielded ruthenacyclopentatrienes [η 5:σ-Me2C (C5H4)(C2B10H10)]Ru[=C2(R2)2C2(CH2)3] in >85% yield. These new complexes were fully characterized by various spectroscopic techniques, elemental analyses and single-crystal X-ray diffraction studies. The possible reaction mechanism was proposed. 相似文献
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Ligand modifications have played a crucial role in developing new catalyst precursors. A novel class of “constrained-geometry”ligands bearing a carboanion functionality has been developed by linking o-carboranyl and n-ligand together. They offer group 4 metal complexes higher activity in olefin polymerization compared to those with appeoded heteroatom systems. The results show that the [{η^5:σ-Me2A(C5H4)(C2B10H10)}M] moiety remains intact in olefin polymerization and insertion reactions of various unsaturated molecules, and the electron-deficient yet sterically hindered icosahedral carborane does play an important role in the reactions. This article provides an overview of our recent work on this subject. 相似文献
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The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of ico-sahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsatu... 相似文献
10.
Nan Sheng YuSong Tu Pan Guo RongZheng Wan ZuoWei Wang HaiPing Fang 《中国科学:物理学 力学 天文学(英文版)》2017,60(4):040511
Using molecular dynamics simulations, we show that an asymmetrically shaped nanoparticle in dilute solution possesses a spontaneously curved trajectory within a finite time interval, instead of the generally expected random walk. This unexpected dynamic behavior has a similarity to that of active matters, such as swimming bacteria, cells, or even fish, but is of a different physical origin. The key to the curved trajectory lies in the non-zero resultant force originated from the imbalance of the collision forces acted by surrounding solvent molecules on the asymmetrically shaped nanoparticle during its orientation regulation. Theoretical formulae based on microscopic observations have been derived to describe this non-zero force and the resulting motion of the asymmetrically shaped nanoparticle. 相似文献
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