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Island Homoaromaticity in the W-Shaped 2,4-Diphospha-3-arsapentadienide Anion and Related Compounds – Theoretical and Experimental Investigations

Authors

  • Alexander B. Rozhenko,

    1. Institute of Organic Chemistry of the National Academy of Sciences of Ukraine, Murmans'ka str. 5, 02660 Kyiv, Ukraine, Fax: +380-44-573-2543
    2. Fakultät für Chemie der Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
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  • Alexander Ruban,

    1. Institute of Organic Chemistry of the National Academy of Sciences of Ukraine, Murmans'ka str. 5, 02660 Kyiv, Ukraine, Fax: +380-44-573-2543
    2. Anorganisch-Chemisches Institut der Universität Bonn, Gerhard-Domagk-Str. 1, 5300 Bonn, Germany
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  • Vera Thelen,

    1. Anorganisch-Chemisches Institut der Universität Bonn, Gerhard-Domagk-Str. 1, 5300 Bonn, Germany
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  • Martin Nieger,

    1. Anorganisch-Chemisches Institut der Universität Bonn, Gerhard-Domagk-Str. 1, 5300 Bonn, Germany
    2. Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P. O. Box 55 (A.I. Virtasen aukio 1), 00014 University of Helsinki, Finland
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  • Karri Airola,

    1. Department of Chemistry, University of Jyväskylä, P. O. Box 35, 40114 Jyväskylä, Finland
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  • Wolfgang W. Schoeller,

    1. Fakultät für Chemie der Universität Bielefeld, Postfach 100131, 33501 Bielefeld, Germany
    2. Department of Chemistry, University of California, Riverside, CA 92521-0403, USA
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  • Edgar Niecke

    1. Anorganisch-Chemisches Institut der Universität Bonn, Gerhard-Domagk-Str. 1, 5300 Bonn, Germany
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Abstract

A series of anions with general formula (R2C=P)2Pn (Pn = N, P, As, Sb; R = H, Me, CF3, SiH3, SiMe3, SiF3) was investigated theoretically at the DFT (RI-BP86/TZVP) and RI-MP2/TZVP levels of approximation. Significantly sharpened central PPnP bond angles were predicted for the species with π-acceptor R substituents. The corresponding bond angle values decrease in the order Pn = N >> P > As > Sb. This finding is in agreement with the previously published structural data for [(Me3Si)2C=P]2P. An island homoaromaticity was proposed as a suitable explanation for the observed effect. In more detail, it consists of shifting negative charge to the electron-withdrawing terminal groups with formation of a homologue of an aromatic heterocyclopropylium cation as the central moiety. Calculated structures and charge distributions are in agreement with the proposed model as well as with the molecular structure of the newly synthesized 2,4-diphospha-3-arsapentadienyl anion.

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