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  • 1
    ISSN: 1572-8862
    Keywords: Tungsten ; chloro ; phosphine ; tetranuclear cluster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract From the reaction between W2Cl6(PEt3)2 and H2O in tetrahydrofuran the dark green crystalline compound [Et3PH][W4O3Cl7(PEt3)3] was obtained and characterized by X-ray crystallography. At −155° the cell dimensions werea=b=c=20.392(3) Å,Z=8,d calcd=2.36 g cm−3 in the space group I23. The compound is a triethylphosphonium salt of the [W4O3Cl7(PEt3)3]− anion. The latter contains a tetrahedron of tungsten atoms with W−W=2.61 Å (ave) and may be viewed as a W3(μ-Cl)3Cl3(PEt3)3 cluster capped by ad 0-[WO3Cl]− unit and this has proved useful in examining the bonding within the cluster by use of the M.O. calculational method of Fenske and Hall. The cluster anion has crystallographically imposed C3v symmetry. Theoxo-groups bridge the tungsten atoms in a notably asymmetric manner W−O=1.87(2) Å and 2.04(2) Å with the shorter distances being involved with the capping [WO3Cl]− unit. The W−P bonds lie in the W3(μ3-Cl)3 plane and the three terminal W−Cl bonds are trans to theoxo-bridges.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8862
    Keywords: Tungsten ; triple bond ; alkoxide ; amide ; β-diketonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The reactions between 1,2-W2 R 2(NMe2)4 (R=Et and Ph) and 1,2-W2 R 2(OPr i )4 (R=CH2Ph and Bu t ) and Bu t -CHCOCH2COBu t (Bu t -acacH) (4 equiv)in pentane or hexane give, respectively, W2 R 2NMe2)2 (Bu t -acac)2 and W2 R 2(OPr i )2 (Bu t -acac)2 that are remarkably thermally and photochemically robust with respect to further reaction and reductive elimination to give the targeted compounds W2(Bu t -acac)4. The new compounds have been characterized by elemental analysis, infrared, and1H NMR spectroscopy and forR = Et and CH2Ph by single crystal X-ray studies. In each compound there are four coordinate W atoms united by unbridged W-W triple bonds. Crystal data for W2Et2(NMe2)2 (Bu t -acac)2 at −165°C:a=17.115(2) Å,b=10.542(1) Å,c = 19.786(3) Å.β = 98.55(1)°,Z = 4, and space group C2/c; for W2(CH2Ph)2 (OPr i )2 (Bu t -acac)2 at −157°C:a=23.547(5) Å,b = 10.784(2)Å,c = 21.105(5) Å,β = 127.20(1)°,Z = 4, and space group C2/c.
    Type of Medium: Electronic Resource
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