Scheme 2.

Proposed 3-step reaction mechanism for the pre-steady state reaction of EAL or [D₂]EAL with EA and/or [D₄]EA, showing Co=C cleavage (k₁), H^. abstraction (k₂) and subsequent irreversible substrate radical rearrangement (k₃). In a 2-step mechanism, k₁ and k₂ are concerted (called k₂ in Table 3). The horizontal dotted lines delineate groups of species that cannot interconvert in our kinetic model and those species in boxes are starting species: E,S=H,H, H,D, D,H and D,D, respectively from top to bottom.