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  • Heterosiloxanes  (3)
  • Phosphane boranes
  • Ylides
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Monatshefte für Chemie 111 (1980), S. 1233-1244 
    ISSN: 1434-4475
    Schlagwort(e): Metallocycles ; Organometallic compounds of do and d10 metals ; Phosphane boranes ; Phosphorus Ylides ; Ylide complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Dehydrohalogenation and metallation of boranato-bis-trimethylphosphonium salts (1), using two equivalents of a lithiumalkyl in tetrahydrofuran, leads to a solvated organolithium reagent H2B[(CH3)2PCH2]2Li (3) which can be converted into a 1:1n1-complex with tetramethylethylenediamin (4).3 reacts with anhydrous metal(II) halides to form spirocyclic coordination compounds of the type H2B[(CH3)2PCH2]2 M[CH2P(CH3)2]2BH2 (5–9,M=Be, Mg, Zn, Cd, Hg). The reaction of [(CH3)3PBH2P(CH3)3]Br (1) with lithium tetramethylmetalates Li[M(CH3)4],M=Al, Ga, on heating in the absence of a solvent affords the metallocycles H2B[(CH3)2PCH2]2 M(CH3)2 (10, 11) with evolution of methane. The products can be sublimed from the reaction mixture. The proposed structures of the new compounds, with tetrahedrally coordinated central atoms and strong covalent metal-carbon interactions, are supported by mass, IR and1H,7Li,11B,13C, and31P NMR spectra. Compound9 represents a rare case of a tetracoordinate organomercurial, compound5 is the first nonionic tetraalkylberyllate.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 351-354 
    ISSN: 0009-2940
    Schlagwort(e): Triarsa(V)azenes ; Arsenic acid, amid ; Arsenosiloxanes ; Heterosiloxanes ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Synthesis and Structure of Hexakis(trimethylsilyloxy)triarsazeneHexakis(trimethylsilyloxy)triarsa(V)azene [(Me3SiO)2As=N]3 (1) has been prepared from arsenic acid H3AsO4 and hexamethyldisilazane (Me3Si)2NH. According to an X-ray crystal-structure determination 1 features a slightly puckered six-membered As3N3 ring. The formation of 1 proceeds with evolution of ammonia via tris(trimethylsilyl)orthoarsenate (Me3SiO)3As=O (2) as an intermediate, which could be isolated as a by-product. The reaction of 2 with hexamethyldisilazane also gives 1 in high yields. The influence of temperature, solvent and concentration of reactants on product formation has been investigated, and side reactions are discussed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 373-376 
    ISSN: 0009-2940
    Schlagwort(e): Heterosiloxanes ; Arsenosiloxanes ; Arsenates, silyl- ; Arsenites, silyl- ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Arsenosiloxanes: Formation and Decomposition of Trialkylsilyl Arsenates and ArsenitesTris(trialkylsilyl) arsenates(V) are prepared from silver arsenate(V) and chlorotrialkylsilanes or from arsenic acid and hexaalkyldisilazanes. The triethylsilyl ester 1b is stable, but the trimethylsilyl ester 1a undergoes condensation at ambient temperature to give hexamethyldisiloxane and trimethylsilylpolyarsenates(V), including tetrakis(trimethylsilyl) diarsenate(V) (4a). According to an X-ray crystal structure determination of 4a (triclinic, space group P1) centrosymmetrical dimers are present containing two edge-sharing AsO6 octahedra with apex-bridging by two AsO4 tetrahedra. 1a is converted into the salt [(Me3SiO)4As]+ CF3SO3- the cation of which is believed to be a component of the reaction chain. There is also evidence by mass spectrometry for the existence of (Me3SiO)5As (5).  -  Tris(trimethylsilyl) arsenite(III) (6) is prepared from AsCl3 and NaOSiMe3. With modified stoichiometry, side reactions give also the byproducts Cl2AsOSiMe3, ClAs(OSiMe3)2, Cl2AsOAsCl2, Cl2AsOAsCl(OSiMe3), O[AsCl(OSiMe3)]2, and cyclic chloroarsenosiloxanes (12, 13).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 947-950 
    ISSN: 0009-2940
    Schlagwort(e): Heterosiloxanes ; Stibinosiloxanes ; Antimonites(III), silyl-, oxo- ; NMR, solid-state ; NMR; CPMAS ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Treatment of Sb(OSiMe3)3 with NaOSiMe3 in the molar ratio 1:2 in hexane at ambient temperature leads to the formation of Me3SiOSiMe3 and a crystalline complex of the formula Na4[Sb2O(OSiMe3)8] in ca. 35% yield. The composition of the product has been confirmed by elemental analysis and negative-ion CI mass spectrometry. The single crystal X-ray structure analysis (rhombohedral, space group R\documentclass{article}\pagestyle{empty}\begin{document}$\bar{3}$\end{document}c, Z=6) resulted in a disorder model for the complex with pseudo-cubic symmetry owing to virtually random distribution of sodium and antimony atoms over the vertices of an oxygen-centered octahedron with the eight silyloxy groups capping the faces. Low solubility in non-coordinating solvents prevented solution NMR studies, but solid-state NMR investigations using cross polarization and magic-angle spinning techniques (13C, 29Si) allowed the assignment of a point group C2v structure with the SbIII atoms in cis position relative to the oxo center of the complex.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1599-1603 
    ISSN: 0009-2940
    Schlagwort(e): Silicon compounds ; Ylides ; NMR, 13C, 17O, 29Si ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Two series of aminophosphonium ylides with reactive alkoxychlorosilyl substituents (R2N)3P=CHSi(OR')2Cl (1-8, R = Me, Et/R' = Me, Et, iPr, tBu) have been prepared by reaction of the aminophosphonium ylides (R2N)3P = CH2 with the corresponding dialkoxydichlorosilanes Cl2Si(OR')2. Substituent effects have been investigated by heteronuclear solution NMR studies of the nuclei 1H, 13C, 15N, 17O, 29Si, and 31P. These studies show an alternating shielding effect along the C-O-Si-C backbone. Further reactions of the chlorosilylated ylides with the aminomethylenephosphorane (Me2N)3P=CH2 lead to the formation of the bis-ylidic compounds [(Me2N)3P=CH]2Si(OR')2 (9, 10), which are also available in one-pot syntheses. The molecular structure of [(Me2N)3P=CH]2Si(OiPr)2 (9) has been confirmed by single-crystal X-ray diffraction. In the crystal the molecules have two ylidic carbon centers with planar configuration, which are bridged by a nearly tetrahedral silicon atom. Short P-C and Si-C distances indicate a stabilizing effect of the carbanionic centers.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 22 (1983), S. 907-927 
    ISSN: 0570-0833
    Schlagwort(e): Phosphorus ylides ; Coordination modes ; Transition metals ; Ylides ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Phosphorus ylides are not only classical reagents in organic chemistry, but also play an increasingly important role as novel components in organometallic compounds. These metallic “ylide complexes” are either synthesized from “preformed ylides” and coordination compounds by addition or substitution, on the building block principle, or they are formed, in sometimes complicated reactions, from phosphanes, metal complexes, and C1 substrates in the coordination sphere of the metals. The resulting metal-carbon bonds are greatly modified in their properties by the immediate presence of the phosphonium center and often belong to the most stable of M-C structural units. The metal can come from any group of the periodic table, including the lanthanoids and actinoids. Numerous preparative and structural studies are gradually enabling us to gain an overall picture of the scope of this area of research.
    Materialart: Digitale Medien
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