Formation and structures of cationic zirconium complexes in ternary systems image (X = Cl, Me)

Using 13C, 1H and 19F NMR spectroscopy, formation of cationic species was studied in ternary systems (SBI)ZrX2/View the MathML sourceAlBu3i/[CPh3][B(C6F5)4], where X = Cl, Me [(SBI) = rac -Me2Si(Ind)2]. In the first system (X = Cl), the ion pair [(SBI)Zr(μ-Cl)2Zr(SBI)][B(C6F5)4]2 (IV) predominates at low Al/Zr ratios (Al/Zr < 10), whereas at higher Al/Zr ratios (⩾20) in the absence of monomer mainly [(SBI)Zr(μ-H)(μ-C4H7)View the MathML sourceAlBu2i] [B(C6F5)4] (V) is formed. The binuclear complex [(SBI)Zr(μ-Cl)2Zr(SBI)][B(C6F5)4]2 has been characterized crystallographically. Species V is also formed in the system X = Me at high Al/Zr ratios. In the presence of View the MathML sourceAlBu3i, IV displays activity in propylene polymerization and is the most likely precursor of the polymerizing species. Consistent mechanisms have been proposed for the reactions in these catalytic systems.