Rate coefficients for intramolecular homolytic substitution of oxyacyl radicals at selenium

Authors

  • Heather M. Aitken,

    1. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia
    2. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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  • Sonia M. Horvat,

    1. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia
    2. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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  • Carl H. Schiesser,

    Corresponding author
    1. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia
    2. School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
    • School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Victoria 3010, Australia
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  • Ching Yeh Lin,

    1. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia
    2. Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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  • Michelle L. Coote

    Corresponding author
    1. ARC Centre of Excellence for Free Radical Chemistry and Biotechnology, Australia
    2. Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
    • Research School of Chemistry, Australian National University, Canberra, ACT 0200, Australia
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Abstract

Ab initio and density functional calculations predict that intramolecular homolytic substitution reactions of oxyacyl radicals at the selenium atom in ω-alkylseleno-substituted radicals proceed via mechanisms that do not involve hypervalent intermediates. When the leaving radical is tert-butyl, energy barriers (ΔG‡) for these reactions range from 27.1 (G3(MP2)-RAD) kJ mol−1 for the formation of the five-membered cyclic selenocarbonate (6) to 41.5 kJ mol−1 for the six-membered selenocarbonate (8). G3(MP2)-RAD calculations predict rate coefficients in the order of 105–108 s−1 and 102–105 s−1 for the formation of 6 and 8, respectively, at 298.15 K in the gas phase. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 44: 51–58, 2012

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