Syndio- and Isoselective Coordinative Chain Transfer Polymerization of Styrene Promoted by ansa-Lanthanidocene/Dialkylmagnesium Systems

Combinations of the discrete neutral allyl ansa-lanthanidocenes {Me2C(Cp)(Flu)}Nd[1,3-(SiMe3)(2)C3H3] and rac-{Me2C(Ind)(2)}Y[1,3-(SiMe3)(2)C3H3] with di(n-butyl) magnesium constitute efficient binary catalytic systems for the stereocontrolled coordinative chain transfer polymerization of styrene, yielding near-perfect syndio- and isospecific polystyrenes, respectively, with high activities and productivities. By adjusting the amount of di(n-butyl) magnesium, up to 200 polymer chains can be generated per lanthabide center, and good control of the molecular weight features enables the tailoring of low to medium molecular weight polymers.