2,5-dihydro-1,2,5-azasilaborole derivatives studied by 15N and 29Si NMR using Hahn-echo and pseudo-BIRD experiments

Authors

  • Bernd Wrackmeyer,

    Corresponding author
    1. Laboratorium für Anorganische Chemie der Universität Bayreuth, Postfach 101251, D-95440 Bayreuth, Germany
    • Laboratorium für Anorganische Chemie der Universität Bayreuth, Postfach 101251, D-95440 Bayreuth, Germany
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  • ĒRiks Kupče,

    1. Laboratorium für Anorganische Chemie der Universität Bayreuth, Postfach 101251, D-95440 Bayreuth, Germany
    Current affiliation:
    1. Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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    • On leave from the Institute of Organic Synetheis, Latvian Academy of Sciences, Riga, Latvia.

  • Roland Köster,

    Corresponding author
    1. Max-Planck-Institut für Kohlenforschung, D-45466 Mülheim a.d. Ruhr, Germany
    • Max-Planck-Institut für Kohlenforschung, D-45466 Mülheim a.d. Ruhr, Germany
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  • Günter Seidel

    1. Max-Planck-Institut für Kohlenforschung, D-45466 Mülheim a.d. Ruhr, Germany
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  • Dedicated to Professor H. J. Bestmann on the occasion of his 70th birthday.

Abstract

15N and 29Si NMR data of 2,5-hydro-1,2,5-azasilaborole derivatives and related compounds were determined with emphasis on coupling constants 1J(29Si 15N) which cannot be measured from 15N NMR spectra of most boron-nitrogen compounds. In the case of compounds with an Si[BOND]N[BOND]H fragment ψ-Bird pulse sequences, combined with HMQC or HSQC, served for 1H detection of the 29Si resonance with preselection of the 15N-1H spin pair. This permitted the measurement of 1J(29Si 15N) and the determination of its absolute sign (>0). In the absence of an NH group, the coupling constants 1J(29Si 15N) were measured from the 15N satellites in 29Si NMR spectra recorded by using the Hahn-echo extended (HEED) refocused INEPT pulse sequence. Isotope induced chemical shifts 1Δ 15/14N(29Si) were also measured by this technique for all the compounds. The 1J(29Si 15N) values cover the range 8.4–17.0 Hz, depending on the substituents at boron, silicon and nitrogen and on the complexation of the heterocycle.

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