The Dynamics of the Photochemical Decarbonylation of 3-Cyclopentenone

Article abstract of DOI:10.1021/ja00328a009

3-Cyclopentenone undergoes photofragmentation, yielding butadiene and CO.The dynamics of this reaction have been investigated by using the method of time-resolved CO laser absorption spectroscopy.Nascent CO product vibrational energy distributions are directly determined.Dissociation at 193 nm yields CO with N₀:N₁:N₂:N₃:N₄ = 1.00:0.30:0.11:0.04:0.01, dissociation at 249 nm yields CO with N₀:N₁:N₂ = 1.00:0.24:0.03 and dissociation at 308 nm yields CO with N₀:N₁ = 1.00:0.02.The experimental distributions are analyzed by comparing them with distributions calculated by using a statistical model.On this basis, we conclude that only the nonfixed energy of the transition state is available for partitioning among the products' vibrational degrees of freedom and that the products are vibrationally decoupled from one another in the exit channel.Potential energy is thus released in the exit channel primarily to the relative translational motion of the products.