Group IV diamine bis(phenolate) catalysts for 1-decene oligomerization

A family of three group IV based diamine bis(phenolate) catalysts, [M{2,2'-(OC6H2-4,6(t)Bu(2))(2)NHC2H4NH} ((OPr)-Pr-i)(2)] (M = Ti (Cat1), Zr (Cat2), and Hf (Cat3)) were synthesized and characterized. These complexes were employed in 1-decene oligomerization using ([Ph3C] [B(C6F5)(4)]) as an activator at 80 degrees C. NMR spectra of the di (isopropoxy) complexes confirmed C-2-symmetrical structures. Cat2 demonstrated the highest activity followed by Cat3 and Cat1, whereas tacticity Cat1 > Cat2 > Cat3. The origin of this different performance was unveiled by DFT calculations. Interestingly, the increase of oligomerization temperature shifted PDI to the higher values. Moreover, kinetic studies employing population balance approach have been conducted, being outstanding that initiation rate constants were lower than propagation ones by a factor of 100. The precise study of termination reactions by NMR revealed that the significant termination reaction was the creation of two types of unsaturated bonds, i.e. vinylidene and vinylene. The obtained oligomers had viscosity index and pour point values comparable with commercial oils.