959614-11-0Relevant articles and documents
Cationic Scandium Anisyl Species in Styrene Polymerization Using Anisole and N,N-Dimethyl-o-toluidine as Chain-Transfer Agents
Yamamoto, Atsushi,Nishiura, Masayoshi,Yang, Yang,Hou, Zhaomin
, p. 4635 - 4642 (2017)
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 aminobenzyl species 3 and a scandium anisyl species should exist, although the latter was not detected by 1H NMR. The reaction of the half-sandwich scandium bis(anisyl) complex (C5Me4SiMe3)Sc(C6H4OMe-o)2 (4) with 1 equiv of [Ph3C][B(C6F5)4] in THF afforded the THF-coordinated cationic scandium monoanisyl complex [(C5Me4SiMe3)Sc(C6H4OMe-o)(thf)2][B(C6F5)4] (5), which upon reaction with HMPA gave the structurally characterizable HMPA-coordinated analogue [(C5Me4SiMe3)Sc(C6H4OMe-o)(hmpa)2][B(C6F5)4] (6). The 4/[Ph3C][B(C6F5)4] combination in toluene showed high activity for styrene polymerization, selectively yielding the anisyl-end-functionalized sPS. In addition to anisole, N,N-dimethyl-o-toluidine was also found to serve as an efficient CTA for the polymerization of styrene by 1/[Ph3C][B(C6F5)4], which selectively afforded the aminobenzyl-functionalized sPS.
Cationic scandium aminobenzyl complexes. Synthesis, structure and unprecedented catalysis of copolymerization of 1-hexene and dicyclopentadiene
Li, Xiaofang,Nishiura, Masayoshi,Mori, Kyouichi,Mashiko, Tomohiro,Hou, Zhaomin
, p. 4137 - 4139 (2008/03/14)
A structurally well-defined THF-free cationic half-sandwich scandium aminobenzyl complex serves as a novel catalyst for the first copolymerization of 1-hexene with dicyclopentadiene to give the random copolymers with a wide range of 1-hexene contents (32-70 mol%) unavailable previously. The Royal Society of Chemistry.
