Fluxional bis(phenoxy-imine) Zr and Ti catalysts for polymerization

Bis(phenoxy-imine) complexes of zirconium or titanium, a type Fenokishi-Imin catalysts, allow the production polyethylenes with well-defined bimodal molecular weight distributions. Interestingly, by substitution phenyl rings in bis(phenoxy-imine) ligands perfluorinated rings, polymerization reaches desired unimodal behavior. These catalysts have three isomers similar energy that can be easily interconverted. It is likely behavior due to coexistence more than one isomer reaction vessel. Here, we perform static and dynamic DFT calculations understand isomerization catalytic active species. We analyze relative Gibbs energies different barriers for processes. Further characterization obtained through stereo maps, aromaticity measures, NCI plots. Our results show changing group ring, particularly stabilized, thus explaining polyethylene process.