Synthesis of Titanium(IV) and Zirconium(IV) Complexes with an [OSSO]-Type Bis(phenolate) Ligand Bearing a trans-Cyclohexane-1,2-diyl Ring and 1-Hexene Polymerization

The Ti(IV) and Zr(IV) complexes 9 and 11 with a new [OSSO]-type bis(phenolate) ligand bearing a trans-cyclohexane-1,2-diyl ring (6) were synthesized. The reaction of 6 with Ti(OiPr)4 in toluene gave the two C2-symmetric, diastereomeric Ti complexes (Λ*,S*,S*)-9 and (Δ*,S*,S*)-9, the latter of which was characterized by X-ray crystallography. The reaction of 6 with Zr(CH2Ph)4 also provided a mixture of the two C2-symmetric diastereomers (Λ*,S*,S*)-11 and (Δ*,S*,S*)-11. Polymerization of 1-hexene employing 11 as the precatalyst yielded isotactic poly(1-hexene) with high activity. In relation to the activity, an NMR study was carried out for the cationic zirconium complex 12+[B(CH2Ph)(C6F5)3]− in comparison with the corresponding complex 13+[B(CH2Ph)(C6F5)3]−, bearing a trans-cyclooctane-1,2-diyl ring in the ligand.