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Steric Crowding Can Stabilize a Labile Molecule: Solving the Hexaphenylethane Riddle

Authors

  • Prof. Dr. Stefan Grimme,

    Corresponding author
    1. Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie der Universität Bonn, Beringstraße 4, 53115 Bonn (Deutschland)
    • Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie der Universität Bonn, Beringstraße 4, 53115 Bonn (Deutschland)
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  • Prof. Dr. Peter R. Schreiner

    Corresponding author
    1. Institut für Organische Chemie, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, 35392 Giessen (Germany)
    • Institut für Organische Chemie, Justus-Liebig-Universität, Heinrich-Buff-Ring 58, 35392 Giessen (Germany)
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  • This work was supported by the Deutsche Forschungsgemeinschaft in the framework of the SFB858 (“Synergetische Effekte in der Chemie—Von der Additivität zur Kooperativität”).

Abstract

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12 not so angry men: Hexaphenylethane is unstable, a phenomenon traditionally attributed to steric repulsion between the six phenyl rings. However, adding 12 bulky tert-butyl groups, one to each of the 12 meta positions, gives a stabile ethane derivative (see space-filling model and potential energy curve for the dissociation of the central C[BOND]C bond). This unexpected stabilization is shown to result from attractive dispersion interactions between the substituents.

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