- Electrochemical production of low-melting metal nanowires
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The extent of nanotube formation arising from the electrolysis of molten LiCl, using graphite electrodes, is reduced by the addition of salts to the electrolyte. In certain cases (99% LiCl+2), considerable quantities of tin-containing n
- Hsu,Li,Terrones,Terrones,Grobert,Zhu,Trasobares,Hare,Pickett,Kroto,Walton
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Novel poly(silylenealkynes), poly(silylenemethylenes), and poly(silylenephenylenes) with a regular alternating structure in the polymer backbone have been prepared by reductive coupling of special substituted silyl triflates or chlorides with potassium - graphite or by ring-opening polymerization of 1,3-disilacyclobutanes. The functionalization of these polymers with trifluoromethanesulfonic acid and following reactions with grignard reagents, amines, or lithium tetrahydridoaluminate gave novel polymeric derivatives. The protodesilylation reaction could be controlled by using different leaving groups (phenyl-, p-tolyl-, or p-anisyl-groups). In this way, the regular structure of the polymer backbone could be kept during the funtionalization reactions. Novel network-polymers have been obtained by intermolecular hydrosilylation reactions of the modified polymer derivatives. The polymers were characterized by NMR spectroscopy (29Si, 13C, 1H).
- Uhlig, Wolfram
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- Convenient and general synthetic method for photochromic fulgides by palladium-catalyzed carbonylation of 2-butyne-1,4-diols
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Palladium-catalyzed carbonylation of substituted 2-butyne-1,4-diols affords a variety of photochromic fulgides in one step. This methodology provides an alternative to the traditional method based on the Stobbe condensation.
- Kiji, Jitsuo,Okano, Tamon,Takemoto, Akiko,Mio, Shin-Ya,Konishi, Tomonari,Kondou, Yuuichi,Sagisaka, Toshiya,Yokoyama, Yasushi
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- Metal Acetylide Elimination: The Key Step in the Cascade Decomposition and Transformation of Metalated Propargylamines
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Metal acetylide elimination facilitates a novel one-pot cascade metalation and elimination/addition route to a series of unsymmetrical secondary amines from the reaction of secondary propargylamines with organometallic reagents. Spectroscopic evidence suggests a dimetalated amido intermediate rather than an allene.
- Flynn, Matthew T.,Blair, Victoria L.,Andrews, Philip C.
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supporting information
p. 1225 - 1228
(2018/04/30)
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- The ladder structure of LiNb6Cl19
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LiNb6Cl19 was obtained from a solid state reaction of Nb powder, NbCl5, and Li2C2 at 530 °C. The structure was refined by single-crystal X-ray diffraction (space group Pmma (No. 51), Z = 2, a = 2814.6(1) pm, b = 687.35(5) pm, c = 641.39(3) pm). It contains edge and face bridging [NbCl6] octahedra forming the motif of a ladder. The parallel alignment of ladders yields a one-dimensional structure, with lithium ions occupying voids. Each ladder combines characteristic fragments from the niobium chloride structures NbCl4, A3Nb2Cl9 (A = Rb, Cs), and Nb3Cl8. The arrangement of niobium atoms in LiNb6Cl19 appears to be similar with trigonal niobium clusters obtained in the structure of Nb3Cl8. The electronic structures of niobium clusters in Nb3Cl8 and LiNb6Cl19 are compared with each other. WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001.
- Meyer, H.-Jürgen
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p. 2005 - 2010
(2008/10/08)
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- Novel organoborane Lewis acids via selective boron-tin exchange processes - Steric constraints to electrophilic initiation by the boron halide
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With the purpose of preparing novel mono- and bidentate organoboron Lewis acids, the scope and limitations of synthesizing the requisite organoboranes by the boron-tin exchange between a boron halide and the appropriate organostannane have been examined in detail. The following organotin derivatives have been obtained either from the corresponding RMgBr or RLi reagent and MenSnCl4-n or from a Barbier procedure using the organic halide, Me3SnCl and magnesium metal: 1,2-bis(trimethylstannyl)ethyne, o-, m-, and p-bis(trimethylstannyl)benzenes, α,o-bis(trimethylstannyl)toluene, α,α-bis(trimethylstannyl)-o-xylene, and 2,2-dimethyl-2-stannaindane. The individual interaction of the 1,2-bis(trimethylstannyl)ethyne and the isomeric bis(trimethylstannyl)benzenes with Et2BBr produced the corresponding bis(diethylboryl)-derivatives. By contrast, with Et2BCl the α,o-bis(trimethylstannyl)toluene gave only o-diethylboryl-α-trimethylstannyltoluene and with BCl3 the α,α′-bis(trimethylstannyl)-o-xylene formed only α,α′-bis-(chlorodimethylstannyl)-o-xylene. Furthermore, in the attempted double boron-tin exchange between o-bis(trimethylstannyl)benzene and BCl3, an unprecedented rearrangement of the 1-(dichloroboryl)-2-(trimethylstannyl)benzene intermediate into its 1-[chloro(methyl)boryl]-2-(chlorodimethylstannyl) isomer was observed. Likewise, o-bis(trimethylstannyl)benzene with PhBCl2 produced by a similar rearrangement 1-[methyl(phenyl)boryl]-2-(chloro-dimethylstannyl)benzene. The thermolysis of such boranes led variously to definite dimers or ill-defined oligomers. Preliminary studies of the properties of these organoboranes have identified the heightened Lewis acidity of 1,2-bis(diethylboryl)ethyne and the π-electron delocalization involving the 2pΖ-boron orbitals in the 9,10-dihydro-9,10-diboraanthracene system. Finally, an electronic mechanism for the boron-tin exchange has been developed to account for the selectivity of the boron halide's attack at unsaturated carbon-tin bonds.
- Eisch, John J.,Kotowicz, Boguslaw W.
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p. 761 - 769
(2007/10/03)
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