Scandium‐Catalyzed Polymerization of CH₃(CH₂)nCH=CH₂ (n = 0–4): Remarkable Activity and Tacticity Control

The C 3 ‐symmetric trisoxazoline‐supported scandium complex [Sc( i Pr‐trisox)(CH 2 SiMe 3 ) 3 ] ( 2 ) is highly active in the stereospecific polymerization of propene, 1‐butene, 1‐pentene, 1‐hexene and 1‐heptene, when activated with two equivalents of [Ph 3 C][B(C 6 F 5 ) 4 ]. The polymers thus produced were found to possess narrow molecular weight distributions and high levels of tacticity control (up to 99 % mmmm ). Some insight into the nature of the active species was obtained by 1 H, 13 C and 29 Si NMR experiments. In particular, the formation of two equivalents of Ph 3 CCH 2 SiMe 3 at ambient temperature was observed alongside a C 3 ‐symmetric scandium complex tentatively assigned as the dication [Sc( i Pr‐trisox)(CH 2 SiMe 3 )] 2+ .(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)