Lifetimes of carbocations encountered along reaction coordinates for terpene formation

The lifetimes of secondary carbocations proposed to occur along reaction coordinates for terpene-forming carbocation rearrangements were estimated from direct dynamics simulations using density functional theory. Classical secondary carbocations supported by bicyclo[2.2.1] and bicyclo[2.2.2] frameworks have distinct characteristic lifetimes, ca. 40 and 90 fs, respectively. The fusion of additional rings to these frameworks was found to have little effect on these lifetimes, despite altering the potential energy surfaces for rearrangement. Inherent dynamical tendencies of secondary carbocations are shown to be manipulable by alkylation and enforced intermolecular interactions.