Degenerate skeletal rearrangement and energy partitioning in the fragmentation of the norbornyl cation

The electron‐impact‐induced fragmentation of a 13C labelled exo‐2‐norbornyl chloride has been studied. When the norbornyl cation, [C7H11]+, [M – Cl], dissociates by elimination of C2H4, carbon atoms are randomly lost showing that extensive skeletal rearrangement (in addition to the complete hydrogen atom scrambling reported earlier) has taken place in the norbornyl cation prior to dissociation. The metastable ion peak associated with the above fragmentation consists of superimposed gaussian and flat‐top components; it is proposed that these correspond to the formation of isomeric [C5H7]+ daughter ions whose heats of formation differ by ∼0.4 eV.