Steric crowding can stabilize a labile molecule: solving the hexaphenylethane riddle.
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-C bond). This unexpected stabilization is shown to result from attractive dispersion interactions between the substituents.
Mulliken Center for Theoretical Chemistry, Institut für Physikalische und Theoretische Chemie der Universität Bonn, Beringstraße 4, 53115 Bonn, Deutschland. grimme@thch.uni-bonn.de
Stefan
S
Grimme
Peter R
PR
Schreiner
D004980:Ethane / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D013816:Thermodynamics
D004980:Ethane