Quantum mechanical study on the different fluxional mechanisms in a [Pd(η2-olefin) complex

Abstract

In this work, using quantum mechanics, different fluxional mechanisms in a Pd(η2-olefin) complex including sulfur inversion, olefin pseudo rotation, Pd–olefin bond dissociation, propeller-like olefin rotation and a bimolecular process have been investigated theoretically in a solvent environment using the polarisable continuum model (PCM). The activation energy, activation enthalpy and activation Gibbs free energy of the different pathways have been calculated and compared with each other and with experimental results. These activation energies for olefin pseudo rotation, Pd–olefin bond dissociation and propeller-like olefin rotation are greater in comparison with those for the sulfur inversion and bimolecular process, which demonstrates that these latter mechanisms are the dominating paths and make the main contributions in the reaction. The computed activation enthalpies of the sulfur inversion and bimolecular process pathways are in good agreement with the experimental values. All of the calculations have been performed using a hybrid density functional method (B3LYP) in the solution phase.