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The Ring-Closing Reaction of Cyclopentadiene Probed with Ultrafast X-ray Scattering
Lisa Huang1, Lauren Bertram2, Lingyu Ma1
1Department of Chemistry, Brown University, Providence, Rhode Island 02912, United States.
Abstract:
The dynamics of cyclopentadiene (CP) following optical excitation at 243 nm was investigated by time-resolved pump-probe X-ray scattering using 16.2 keV X-rays at the Linac Coherent Light Source (LCLS). We present the first ultrafast structural evidence that the reaction leads directly to the formation of bicyclo[2.1.0]pentene (BP), a strained molecule with three- and four-membered rings. The bicyclic compound decays via a thermal backreaction to the vibrationally hot CP with a time constant of 21 ± 3 ps. A minor channel leads to ring-opened structures on a subpicosecond time scale.
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