Counter anion binding in the phenoxyimine, salan and metallocene olefin polymerization catalysts activated with perfluorophenylborate

Ion pair separation is a process that may influence the activity of homogeneous catalysts of olefin polymerization. We have studied the energy of separation for selected titanium and zirconium metallocene and post-metallocene catalytic ion pairs by means of DFT, dispersion-corrected DFT and Paired Interacting Orbitals method (PIO). Unusually weak cation–anion interactions in the bis(phenoxyimine) systems were attributed to strong electron-donating properties of the phenoxyimine ligands. Energy decomposition analysis (EDA) revealed that almost 70% of the counter ion binding energy results from electrostatic interactions. The PIO method made it possible to analyze the nature of the cation–anion binding and associate its strength with the total overlap population of PIOs.

Graphical abstractEnergy of separation for selected metallocene and post-metallocene catalytic ion pairs was studied. Unusually weak cation–anion interactions in the bis(phenoxyimine) systems were attributed to strong electron-donating properties of the phenoxyimine ligands.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The cation–anion interactions in the olefin polymerization catalysts were studied. ► Bis(phenoxyimine) catalysts exhibit low ion pair separation energy. ► Separation energy is dictated mainly by electronic properties of the ligand.