Reductive Decomposition of Cationic Half-Titanocene(IV) Complexes, Precursors of the Active Species in Syndiospecific Styrene Polymerization

Mixtures of Cp*TiR 3 (with Cp* = C 5 (CH 3 ) 5 and R = CH 3, 13 CH 3 ) and equimolar amounts of B(C 6 F 5 ) 3 or C(C 6 H 5 ) 3 B(C 6 F 5 ) 4, active in the syndiospecific polymerization of styrene, have been investigated by means of ESR spectroscopy. At room temperature the formation of Cp*TiR + complexes has been observed. Rapid insertion of styrene occurs in Ti−R bonds of these cationic Ti(III) complexes, strongly suggesting their role in the stereospecific polyinsertion.