Phosphine-functionalized amidinate ligated rare-earth metal complexes for highly 3,4-selective living polymerization
Fen You1, Jixing Wang1, Hui Liu1
1Department of Polymer Materials, School of Materials Science and Engineering, Shanghai University, Materials Building, Nanchen Street 333, Shanghai 200444, China. xcshi@shu.edu.cn.
Abstract:
A series of rare-earth metal bis(alkyl) complexes have been prepared via protonolysis reactions of tris(aminobenzyl) complexes (Ln(CH2C6H4N(Me)2-o)3) with phosphine-functionalized amidinated ligands (DippNCN(CH2)PPh2, n = 2 (L1-H) and n = 3 (L2-H)). The X-ray diffraction of P2-Sc (DippNCN(CH2)3PPh2Sc(CH2C6H4N(Me)2-o)2) showed the un-coordination of the diphenylphosphine group due to the inherent saturation of the central metal ion. In conjunction with [Ph3C][B(C6F5)4], all the rare-earth metal complexes showed a high catalytic activity for the polymerization of 1,3-conjugated dienes (isoprene, β-myrcene and β-farnesene), affording highly 3,4-regular polymers (up to 100% 3,4-) with high molecular weight and narrow molecular weight distribution. After the abstraction of the alkyl moiety -CH2C6H4N(Me)2-o of P1-Sc by [Ph3C][B(C6F5)4], the species with the coordination of the diphenylphosphine group to the central metal probably formed, as shown in the 31P NMR spectra and DFT calculation results, and it might serve as the true active species in the 3,4-selective polymerization of 1,3-conjugated dienes.
Related Concept Videos
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Ziegler–Natta Chain-Growth Polymerization: Overview
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Anionic Chain-Growth Polymerization: Mechanism
Anionic Chain-Growth Polymerization: Overview
Olefin Metathesis Polymerization: Overview
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists...
![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)

