Quantum Mechanical Study on the Rate Determining Steps of the Reaction between 2-aminopyrimidine with Dichloro-[1-methyl-2-(naphthylazo) Imidazole] Palladium(II) Complex

Abstract

In this work, using quantum mechanics, the mechanism of reaction between 2-aminopyrimidine with dichloro-[1-methyl-2-(naphthylazo) imidazole] palladium(II) complex was investigated. The reaction produces two five-coordinated intermediates which are converted into final products through two possible pathways (nucleophile-dependent pathway and solvent-dependent pathway). The activation energy and activation Gibbs free energy of two pathways have been calculated and compared with each other and experimental results. These activation energies for the solvent-dependent pathway are greater in comparison with the nucleophile-dependent pathway which demonstrates that the latter is the dominating route and makes the main contribution to the reaction. Considering solvent effects, the activation Gibbs free energy for the rate determining step of the nucleophile-dependent pathway was calculated, which was in good agreement with the experimental value. Although the theoretical activation energy shows a suitable behaviour qualitatively, it is not fully consistent with the experimental value. All of the calculations were performed using a hybrid density functional method (B3LYP) in the solution phase (PCM model).