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  • 1
    Electronic Resource
    Electronic Resource
    The Intriguing Structural Characteristics of the Heterosiloxane Molecule Na4[Sb2O(OSiMe3)8] (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 947-950 
    Details
    ISSN: 0009-2940
    Keywords: Heterosiloxanes ; Stibinosiloxanes ; Antimonites(III), silyl-, oxo- ; NMR, solid-state ; NMR; CPMAS ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260415
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  • 2
    Electronic Resource
    Electronic Resource
    NMR spectroscopy of paramagnetic complexes. Part 39For Part 38, see Ref. 3. - natural abundance 2H NMR of paramagnetic sandwich compounds (1993)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 31 (1993), S. 2-6 
    Details
    ISSN: 0749-1581
    Keywords: Paramagnetic NMR ; Natural abundance 2H NMR ; 2H signal narrowing ; 2H isotope effect ; EHMO calculation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The methylated metallocenes (MeCp)2M with M = V, Cr, Mn, Co, Ni (1-5) were investigated by 1H and 2H NMR spectroscopy at natural abundance. The 2H NMR signals are narrower by a factor of up to 30 compared with the corresponding 1H NMR signals, thus establishing an inexpensive method and a general improvement of the NMR spectra of paramagnetic π-complexes. This has allowed the resolution of the signal splitting of Cp deuterons of 1 and 5 which could not be observed earlier in the 1H NMR spectra. The origin of the small (1 and 5) and large (2-4) signal splittings is discussed and related to an extended Hückel calculation. The relative magnitude of the signal splitting is reproduced, but the signal assignment had to be deduced from 13C NMR results. Primary isotope shifts of up to 4.0 ppm were found for 1, 2, 4 and 5. The much higher values for 3 (up to 16.6 ppm) reflect the combined influence of the intrinsic isotope shift and the isotope effect on the spin crossover.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260310103
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