Cationic Scandium Anisyl Species in Styrene Polymerization Using Anisole and N,N-Dimethyl-o-toluidine as Chain-Transfer Agents

Abstract

This work aimed to clarify the involvement of a cationic scandium anisyl species in the scandium-catalyzed chain-transfer polymerization of styrene using anisole as a chain-transfer agent (CTA) as well as its behavior in the presence of N,N-dimethyl-o-toluidine. The reaction of anisole with the catalyst precursor [(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)][B(C6F5)4] (2) generated by the reaction of (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2 (1) with [Ph3C][B(C6F5)4] gave the structurally characterizable anisole-coordinated ion-pair complex [(C5Me4SiMe3)Sc(CH2C6H4NMe2-o)(C6H5OMe)][B(C6F5)4] (3). The aminobenzyl unit in 3 remained intact even in the presence of an excess amount of anisole. The formation of an anisyl species from 3 was not observed by 1H NMR. However, the polymerization of styrene by 3 at either room temperature or 70 °C yielded the anisyl-end-functionalized syndiotactic polystyrene (sPS) as a major product in addition to the dimethylaminobenzyl-end-capped sPS. These results suggest that an equilibrium between the ...