Femtosecond observation of benzyne intermediates in a molecular beam: Berqman rearranqement in the isolated molecule

摘要

In this communication, we report our femtosecond real-time ob- servation of the dynamics for the three didehydrobenzene mole- cules to-, m-, and o-benzyne) generated from 1,4-, 1,3-, and 1,2- dibromobenzene, respectively, in a molecular beam, by using femtosecond time-resolved mass spectrometry. The time required for the first and the second C-Br bond breakage is less than 100 fs; the benzyne molecules are produced within 100 fs and then decay with a lifetime of 400 ps or more. Density functional theory and high-level ab initio calculations are also reported herein to eluci- date the energetics along the reaction path. We discuss the dynamics and possible reaction mechanisms for the disappearance of benzyne intermediates. Our effort focuses on the isolated molecule dynamics of the three isomers on the femtosecond time scale.