Cl -anion and one Cl -anion of {100} mononuclear TiCl4 were the most common, composing 21.5% of all TiCl4 species, i.e., this system, even when both stereo-controlling ligands are present, is unlikely to be highly stereospecific. When ID was present, the most common ligands became ID itself, but there was also an increase in bridged Cl -of MgCl2, a result of the preferred formation of concavities. This Cl -anion is considered much more capable of enforcing the stereospecificity than the terminal one, as its position is fixed by two Mg 2+ cations. Between the two IDs, the presence of {100} bridging adsorption profoundly increased the variety of motifs present in stable structures for DEP and also allowed it to be the stereocontrolling ligand more frequently than DE (Figure ). In conclusion, the distribution of TiCl4 species found in this paper strongly aligns with propylene polymerization tendencies: A higher TiCl4 content results in an increase in the isotacticity of produced PP, but not to the extent observed with donors; The environment around mononuclear TiCl4 is much more varied in the case of DEP than DE, which is expected to diversify the active sites and the polymer chains, hence, the broader molecular weight distribution of PP.