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961.
962.
Dr. Tobias Böttcher Simon Steinhauer Dr. Lesley C. Lewis‐Alleyne Beate Neumann Dr. Hans‐Georg Stammler Dr. Bassem S. Bassil Prof. Dr. Gerd‐Volker Röschenthaler Prof. Dr. Berthold Hoge 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(2):893-899
The addition of BCl3 to the carbene‐transfer reagent NHC→SiCl4 (NHC=1,3‐dimethylimidazolidin‐2‐ylidene) gave the tetra‐ and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3]+ and [(NHC)2SiCl3]+ with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC→SiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 ? OEt2, on the other hand, gave NHC→BF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl)silane (C2F5)2SiCl2 was treated with NHC→SiCl4. In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3]+ and [(NHC)2SiCl3]+ were detected with [(C2F5)SiCl3]? as counterion. A similar result was already reported for the reaction of NHC→SiCl4 with (C2F5)2SiH2, which gave [(NHC)2SiCl2H][(C2F5)SiCl3]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC→Si(C2F5)2Cl2 and NHC→Si(C2F5)2ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron‐poor silylenes. Furthermore, the reactivity of NHC→SiCl4 towards phosphines is discussed. The carbene complex NHC→PCl3 shows similar reactivity to NHC→SiCl4, and may even serve as a carbene‐transfer reagent as well. 相似文献
963.
964.
Lewis B. Tunnicliffe Alan G. Thomas James J. C. Busfield 《Journal of Polymer Science.Polymer Physics》2011,49(15):1084-1092
The effect of silica nanofiller surface chemistry on compounded particle size and high strain particle dewetting in a semitransparent nanosilica‐filled elastomer composite was determined using backscattered visible light and transmitted light, respectively. The integrated intensities of backscattered light from the samples were collected at various visible wavelengths for thin‐film composites using ultraviolet–visible spectrometer with an integrating sphere. The data revealed strong Rayleigh‐type scattering from compounded filler particles. Size information was extracted and found to broadly correlate with scanning electron microscopy image analysis of fracture surface. Incorporation of a siloxane surface treatment chemical during compounding resulted in a reduced average filler particle size in the cured composite. On extension of the samples, an optical transition was observed only in the filled composites. At high strains, the semi transparent samples displayed an abrupt drop in transparency becoming opaque. This was quantified using a simple light transmission‐sample extension technique. Strain‐induced crystallization was discounted as the cause for the transition by X‐ray diffraction analysis. The onset yield stress for the optical transition was found to be filler surface‐chemistry‐dependent with the siloxane‐treated filler exhibiting a greatly increased onset stress value. These observations were discussed and rationalized in terms of filler particle–matrix dewetting and cavitation at high strains. Matrix–filler dewetting was distinguished from matrix cavitation by comparison with Beer–Lambert behavior derived from unstrained samples. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011. 相似文献
965.
Mitch Little 《世界电子元器件》2012,(1):41-41,43
技术继续向我们生活的方方面面进一步渗透,包括计算、工业/制造、移动技术(例如电话和平板电脑)、医学进步以及可再生能源(例如电动汽车)。尽管隶属这些行业的应用已经颇为丰富,但仍有巨大的扩展空间。半导体继续充当所有这些扩展领域的创新推动力。一般来说,半导体市场的成长基本都围绕着给生活中涉及的设备添加智能。连通性正是可以发展和创新的重要领域之一,这是因为嵌入式系统越来越多,使之相互之间能够互相交流的需求日益强烈。 相似文献
966.
967.
968.
969.
Uranium Metalla‐Allenes with Carbene Imido R2C=UIV=NR′ Units (R=Ph2PNSiMe3; R′=CPh3): Alkali‐Metal‐Mediated Push–Pull Effects with an Amido Auxiliary 下载免费PDF全文
Dr. Erli Lu Dr. Floriana Tuna Dr. William Lewis Prof. Dr. Nikolas Kaltsoyannis Prof. Dr. Stephen T. Liddle 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(33):11554-11558
We report uranium(IV)‐carbene‐imido‐amide metalla‐allene complexes [U(BIPMTMS)(NCPh3)(NHCPh3)(M)] (BIPMTMS=C(PPh2NSiMe3)2; M=Li or K) that can be described as R2C=U=NR′ push–pull metalla‐allene units, as organometallic counterparts of the well‐known push–pull organic allenes. The solid‐state structures reveal that the R2C=U=NR′ units adopt highly unusual cis‐arrangements, which are also reproduced by gas‐phase theoretical studies conducted without the alkali metals to remove their potential structure‐directing roles. Computational studies confirm the double‐bond nature of the U=NR′ and U=CR2 interactions, the latter increasingly attenuated by potassium then lithium when compared to the hypothetical alkali‐metal‐free anion. Combined experimental and theoretical data show that the push–pull effect induced by the alkali metal cations and amide auxiliary gives a fundamental and tunable structural influence over the C=UIV=N units. 相似文献
970.
Kevin P. Klubek Shou-Cheng Dong Liang-Sheng Liao Ching W. Tang Lewis J. Rothberg 《Organic Electronics》2014,15(11):3127-3136
A blue phosphorescent emitter based on tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III), Ir(iprpmi)3, as the dopant and 3,3′-bis(N-carbazolyl)biphenyl, mCBP, as the host have been evaluated in OLED devices. By optimizing the dopant concentration and the materials for the electron and hole-transport layers, external quantum efficiencies greater than 20% have been achieved. Improved device lifetimes over those using the classic light-blue dopant FIrpic have also been achieved. These improvements can be attributed to the control of the electron-hole recombination and emission regions within the emitter layer as well as the choice of material for the transport layers. 相似文献