Half-lanthanidocenes catalysts via the borohydride/alkyl route: A simple approach of ligand screening for the controlled

The borohydride/alkyl (B/A) route initially reported for isoprene has been applied successfully to the polymerization of styrene. This method provides via an in situ approach an interesting tool for the assessment of the influence of a ligand on the performance of half-lanthanidocene catalysts. All systems lead to well-controlled oligomerization/polymerization processes. This method is thus a convenient tool for the controlled polymerization of styrene starting from a common trisborohydride precursor and commercial ligands. The influence of the nature of several ligands on the activity could be established, with trends corresponding to those obtained starting from the isolated precursors: HCp similar to HCp(Ph3) > HCp*(Cp = C(5)H(5) CP(Ph3) = 1, 2,4-Ph(3)C(5)H(2), Cp* = C(5)Me(5)). These results suggest an influence of the electron donating ability of the ligand rather than steric requirements.