Nonclassical 21-Homododecahedryl Cation Rearrangement Revisited

The degenerate rearrangement in the 21-homododecahedryl cation (1) has been studied via density functional theory computations and Born Oppenheimer Molecular Dynamics simulations. Compound 1 can be described as a highly fluxional hyperconjugated carbocation. Complete scrambling of 1 can be achieved by the combination of two unveiled barrierless processes. The first one is a rotation of one of the six-membered rings via a 0.8 kcal.mol(-1) barrier, and the second one is a slower interconvertion between two hyperconjomers via an out-of-plane methine bending (Delta G(double dagger) = 4.0 kcal.mol(-1)).