Reactivity of group 4 benzamidinate complexes towards mono- and bis-substituted silanes and 1,5-hexadiene

Zirconium and titanium bis(benzamidinate) dimethyl complexes were found to be active catalytic precursors for the oligomerization of mono- and bis-substituted silanes. The activation of such complexes, by an excess of MAO or by an equimolar amount of B(C₆F₅)₃, increases the catalytic activity of the complexes and the molecular weight of the obtained oligosilanes. The maximum polymerization index that was accomplished (n = 90) is by far the largest obtained with other organometallic complexes. In addition, the activated benzamidinate catalysts were also found to be active for the polymerization of 1,5-hexadiene producing poly(methyl-1,3-cyclopentane). For the latter, the results obtained with C₂-symmetry bis(benzamidinate) dimethyl complexes were compared with a chiral complex bearing a myrtanyl group at the benzamidinate ligand.