Further investigation of the HCl elimination in the photodissociation of vinyl chloride at 193 nm: a direct MP2/6-31G(d,p) trajectory study

Direct MP2/6-31G(d,p) classical trajectories were performed to further explore the photodissociation of vinyl chloride at 193 nm. In general, the results are in good agreement with those obtained previously using a semiempirical AM1 Hamiltonian supplemented with specific reaction parameters (SRPs). The calculations support the earlier proposal that the three-center elimination of HCl and the isomerization of vinylidene to acetylene take place in a concerted, nonsynchronous fashion. On the other hand, the results indicate that the four-center channel produces rotationally hot HCl molecules while low rotational states of HCl are essentially populated when vinyl chloride dissociates through the three-center channel. This result is at odds with a previous conclusion inferred from fully resolved vibration–rotation emission spectra of HCl and simple theoretical models.