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Jürgen Tölke 《Journal of Geometry》2002,73(1-2):194-198
The isotropic analogue of the cubic of Cazamian [2] was studied by O. R?schel [4]. We prove two additional results. These
are similar to those of H. Sachs [5] and O. R?schel [4, Theorem 4] for the isotropic ABRAMESCU-circle. We make use of the
projective differential geometry [1,3].
Received 20 November 2000. 相似文献
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Takeaki Iwamoto Takashi Abe Kunihisa Sugimoto Daisuke Hashizume Hiroshi Matsui Ryohei Kishi Masayoshi Nakano Shintaro Ishida 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(13):4415-4419
Bicyclo[1.1.0]tetrasil‐1(3)‐ene 1 , a tetrasilicon analogue of bicyclo[1.1.0]but‐1(3)‐ene that contains a formal double bond between bridgehead silicon atoms in an inverted geometry, was synthesized and isolated in the form of thermally stable orange crystals. The distance between the bridgehead Si atoms in 1 is much longer than those in typical Si=Si bonds, but still shorter than that of a previously reported pentasila[1.1.1]propellane. DFT calculations suggest that the bridgehead bond in 1 comprises a σ bond with an inverted geometry and a π bond. This notion is supported by the UV/Vis spectrum of 1 , which exhibits several absorption bands in the UV/Vis region. While 1 is stable toward typical trapping agents for Si=Si double bonds, 1 reacts with carbon tetrachloride to furnish a hexachlorotetrasilane. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(47):15304-15308
The preparation of an unprecedented GeI‐GeI bonded digermylene [K2{Ge2(μ‐κ2:η2:η4‐2,6‐(2,6‐iPr2C6H3‐N)2‐4‐CH3C5H2N)2}] in an eclipsed conformation stabilized by two bridging diamidopyridyl ligands is presented. Although it exhibits an eclipsed conformation, the Ge−Ge bond length is 2.5168(6) Å, which is shorter than those in the trans ‐bent and gauche digermylenes. In combination with two pendant amido groups, the GeI2 motif is employed as a building block to assemble the first example of octagermylene [Ge4(μ‐κ2:κ1‐2,6‐(2,6‐iPr2C6H3‐N)2‐4‐CH3C5H2N)2]2 showing a cyclic configuration and containing three distinct types of GeI−GeI bonds. 相似文献
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