DFT study on the preactivation reaction of a palladium catalyst precursor in phosphine-free Heck reactions

The mechanism of the preactivation process of trans-dichlorobis(diethanolamine-N) palladium(II) complex is investigated using density functional theory. The role of diethanolamine (a solvent for the reaction in the absence of a strong base) and acetonitrile (solvent for the reaction in the presence of a strong base) is analyzed by using a discrete model. The Onsager model is applied to assess the effect of the bulk medium. Both models show that diethanolamine activates the complex and thus is a better suited solvent for the Heck reactions of the investigated complex.