5 years ago

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

Cationic Scandium Anisyl Species in Styrene Polymerization Using Anisole and N,N-Dimethyl-o-toluidine as Chain-Transfer Agents
Atsushi Yamamoto, Yang Yang, Masayoshi Nishiura, Zhaomin Hou
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.

Publisher URL: http://dx.doi.org/10.1021/acs.organomet.7b00526

DOI: 10.1021/acs.organomet.7b00526

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.