Synthesis of Imidazolin-2-iminato Titanium Complexes Containing Aryloxo Ligands and Their Catalytic Performance in the Polymerization of α‑Olefins

The synthesis of
mixed (aryloxo)­(imidazolin-2-iminato)­titanium
dichloride complexes is presented. Full characterization of the complexes,
including solid-state X-ray diffraction analysis of four complexes,
is reported. Their catalytic activity in the polymerization of ethylene,
propylene, 1-hexene, and 1-octene was studied. The different substituents
at the aryloxo moiety were found to have a substantial impact on the
reactivity of the complexes, indicating the need for a balance of
steric and electronic effects. The complex (1,3-di-tert-butylimidazolin-2-iminato)­(2,6-di-tert-butyl-4-methylphenoxide)­titanium
dichloride (1) was found to be the most active in the
polymerization of ethylene, whereas the complex (1,3-di-tert-butylimidazolin-2-iminato)­(2,6-di-tert-butylphenoxide)­titanium
dichloride (2) was found to be the most active in the
polymerization of propylene. Interestingly, all complexes were more
active in the polymerization of propylene than in that of ethylene.