title: Reaction mechanisms of a photo-induced [1,3] sigmatropic rearrangement via a nonadiabatic pathway.
abstract: Time-resolved Fourier transform infrared absorption spectroscopy measurements and B3LYP/cc-pVDZ calculations have been conducted to characterize the reaction dynamics of a remarkable photoinduced 1,3-Cl sigmatropic rearrangement reaction upon 193 or 266 nm excitation of the model systems acryloyl chloride (CH(2)CHCOCl) and crotonyl chloride (CH(3)CHCHCOCl) in solution. The reaction is elucidated to follow nonadiabatic pathways via two rapid ISC processes, S(1) --> T(1) and T(1) --> S(0), and the S(1)/T(1) and T(1)/S(0) surface intersections are found to play significant roles leading to the nonadiabatic pathways. The S(1) --> T(1) --> S(0) reaction pathway involving the key participation of the T(1) state is the most favorable, corresponding to the lowest energy path. It is also suggested that the photoinduced 1,3-Cl migration reaction of RCHCHCOCl (R = H, CH(3)) proceeds through a stepwise mechanism involving radical dissociation-recombination, which is quite different from the generally assumed one-step concerted process for pericyclic reactions.
authors.affiliation: State Key Laboratory of Molecular Reaction Dynamics, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Wu
authors.forename: Kunhui
authors.initials: K
authors.lastname: Liu
authors.forename: Chunfan
authors.initials: C
authors.lastname: Yang
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhao
authors.forename: Huan
authors.initials: H
authors.lastname: Wang
authors.forename: Youqing
authors.initials: Y
authors.lastname: Yu
authors.forename: Hongmei
authors.initials: H
authors.lastname: Su