| Abstract
| - CASSCF computations suggest that the ground-state potential energy surface of housane radicalcations is centered around a conical intersection (and its surrounding Jahn−Teller-type surface) at a planar,symmetric cyclopentane-1,3-diyl geometry. In our reactivity model, this region is connected to the reactantsvia a bridge-bending coordinate and to the products via a shift coordinate. The preference for the spin-localizedplanar intermediate is caused by the preferential energy stabilization along a charge localization coordinate(the derivative-coupling coordinate at the conical intersection). Mechanistically, our computations show thatthe reaction proceeds in two steps: the breakage of the one-electron bond of the reactants, which produces theasymmetric, quasi-planar intermediate and is the rate-determining step, and the subsequent 1,2 rearrangement,which is essentially barrierless. The reaction results in the selective 1,2 migration of the original endo substituentof the reactant.
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