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

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.