- Crystal structure and dimorphism of silicon tetraisocyanate Si(NCO) 4
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Silicon tetraisocyanate Si(NCO)4 was obtained by reacting SiCl4 and AgNCO in boiling toluene. The colourless liquid was analyzed by Raman and NMR spectroscopy. Structural studies on solid Si(NCO) 4 (melting point: +26°C) have revealed it to exist in two polymorphic modifications. According to the results of single-crystal X-ray diffraction, at T = -173°C, α-Si(NCO)4 exhibits triclinic symmetry (Pβar{1}$; a = 10.05(5), b = 10.50(2), c = 14.32(1) A, α = 91.62(1)°, β = 92, 32(1)°, γ = 99.68(1)°; V = 1488.56(3) A3; Z = 8). Above T = -33°C, a monoclinic phase evolves, β-Si(NCO)4 (P21/c; a = 10.78(3), b = 7.11(1), c = 10.27(5) A, β = 99, 06(9)°; V = 777.39(1) A3; Z = 4). The charge distribution was studied for both polymorphs. In the solid state, Si(NCO)4 is a tetrahedral molecule with the Si-N=C=O linkages bent at the nitrogen atoms. Copyright
- Schmidt, Carsten Ludwig,Jansen, Martin
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p. 275 - 278
(2012/05/20)
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- Chemical process
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Optionally substituted silicon isocyanates are prepared by reacting a corresponding silicon halide with an alkali metal cyanate or an alkaline earth metal cyanate in an inert solvent having a dielectric constant below about 10, in the presence of a crown ether as a catalyst.
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