Rehybridization dynamics into the pericyclic minimum of an electrocyclic reaction imaged in real-time

Authors

• Y. Liu, SLAC National Accelerator Laboratory, Stony Brook University
• D. M. Sanchez, SLAC National Accelerator Laboratory, Stanford University, Lawrence Livermore National Laboratory
• M. R. Ware, SLAC National Accelerator Laboratory
• E. G. Champenois, SLAC National Accelerator Laboratory
• J. Yang, SLAC National Accelerator Laboratory, S-1027 Tsinghua University
• J. P. F. Nunes, University of Nebraska-Lincoln, Harwell Science Campus
• A. Attar, SLAC National Accelerator Laboratory
• Martin Centurion, University of Nebraska - LincolnFollow
• J. P. Cryan, SLAC National Accelerator Laboratory
• R. Forbes, SLAC National Accelerator Laboratory
• K. Hegazy, SLAC National Accelerator Laboratory
• M. C. Hoffmann, SLAC National Accelerator Laboratory
• F. Ji, SLAC National Accelerator Laboratory
• M.-F. Lin, SLAC National Accelerator Laboratory
• D. Luo, SLAC National Accelerator Laboratory
• S. K. Saha, University of Nebraska–LincolnFollow
• X. Shen, SLAC National Accelerator Laboratory
• X. J. Wang, SLAC National Accelerator Laboratory
• T. J. Martínez, SLAC National Accelerator Laboratory, Stanford University
• T. J. A. Wolf, SLAC National Accelerator Laboratory

Document Type

Article

Date of this Version

5-18-2023

Citation

Nature Communications | ( 2023) 14:2795. https://doi.org/10.1038/s41467-023-38513-6

Comments

Open access.

Abstract

Electrocyclic reactions are characterized by the concerted formation and cleavage of both σ and π bonds through a cyclic structure. This structure is known as a pericyclic transition state for thermal reactions and a pericyclic minimum in the excited state for photochemical reactions. However, the structure of the pericyclic geometry has yet to be observed experimentally.We use a combination of ultrafast electron diffraction and excited state wavepacket simulations to image structural dynamics through the pericyclic minimum of a photochemical electrocyclic ring-opening reaction in the molecule α-terpinene. The structural motion into the pericyclic minimum is dominated by rehybridization of two carbon atoms, which is required for the transformation from two to three conjugated π bonds. The σ bond dissociation largely happens after internal conversion from the pericyclicminimum to the electronic ground state. These findings may be transferrable to electrocyclic reactions in general.