Characterize the Hydrogen Roaming Mechanism in Cyclobutanone Photodynamics

Characterize the hydrogen-atom roaming mechanism in cyclobutanone photochemistry, wherein a hydrogen originally bonded to an α carbon detaches and migrates toward the oxygen atom, by establishing whether this pathway reliably occurs and delineating its mechanistic details during and after S1/S0 internal conversion.

Background

During trajectory analysis of photoproducts, the authors observed a rare event where an α-carbon hydrogen atom detached and roamed toward the oxygen, suggestive of a roaming mechanism. Due to the small number of occurrences and limited trajectory survival, they could not confidently predict or describe this mechanism.

Clarifying whether hydrogen roaming is a reproducible, mechanistically coherent pathway in cyclobutanone’s excited-state dynamics—and, if so, its intermediates, timescale, and product outcomes—remains an unresolved task.