Versatile 2-Methoxyethylaminobis(phenolate)yttrium Catalysts: Catalytic Precision Polymerization of Polar Monomers via Rare Earth Metal-Mediated Group Transfer Polymerization

Abstract

The present study is one of the first examples for rare earth metal-mediated group transfer polymerization (REM-GTP) with non-metallocene catalyst systems. 2-Methoxyethylaminobis(phenolate)yttrium trimethylsilylmethyl complexes were synthesized and showed moderate to high activities in the rare earth metal-mediated group transfer polymerizations of 2-vinylpyridine, 2-isopropenyl-2-oxazoline, diethyl vinylphosphonate, diisopropyl vinylphosphonate, and N,N-dimethylacrylamide as well as in the ring-opening polymerization of β-butyrolactone. Reaction orders in catalyst and monomer were determined for the REM-GTP of 2vinylpyridine. The mechanistic studies revealed that the catalyst systems follow a living monometallic group transfer polymerization mechanism allowing a precise molecular-weight control of the homopolymers and the block copolymers with very narrow molecular weight distributions. Temperaturedependent reaction kinetics were conducted and allowed conclusions about the influence of the bulky substituents around the metal center on the polymerization activity. Additional polymerization experiments concerning the combination of REM-GTP and ROP to obtain block copolymers were performed.

Stereospecific catalytic precision polymerization of 2-vinylpyridine via rare earth metal-mediated group transfer polymerization with 2-methoxyethylamino-bis(phenolate)-yttrium complexes

“…[28][29][30][31] Apart from the mentioned examples only few groups investigated the stereospecific polymerization of 2VP. 49 A correlation between the steric demand of the ortho position in the ligand structure and the activity was observed. Rare earth metal-mediated group transfer polymerization (REM-GTP) in contrast is a relatively recent polymerization method for 2VP.…”

“…Subsequent mechanistic studies of Soum and Fontanille with organomagnesium compounds revealed that the stereocontrol derives from a Markov-chain end control through a favoured gauche coordination of two monomers to the metal cation. 49 Mechanistic studies revealed a living monometallic group-transfer polymerization mechanism and kinetic studies showed the exceptional activity for the polymerization of 2VP. [32][33][34][35][36] In addition Frustrated Lewis pair, 37,38 anionic [39][40][41][42][43][44] and radical [45][46][47][48] polymerizations have been applied to synthesize functional but atactic P2VP based materials.…”

“…26,27 They were able to obtain isotactic P2VP with magnesium amides. 21,36,49 GTP has several advantages e.g. [28][29][30][31] Apart from the mentioned examples only few groups investigated the stereospecific polymerization of 2VP.…”

“…36,49 REM-GTP of 2VP proceeds rapidly and the primary limitation is an inefficient initiation. 36,49 REM-GTP of 2VP proceeds rapidly and the primary limitation is an inefficient initiation.…”

Lanthanides and actinides: Annual survey of their organometallic chemistry covering the year 2014

“…The reaction of LY(CH 2 Ph) 2 (THF) with 2-phenylpyridine in a 1:2 molar ratio in THF at 30 with the free bis(phenols) in a mixture of toluene and n-pentane. [20] M a n u s c r i p t In the course of this study, it was found that the reaction conditions play a key role in the formation of the final products. For example, reactions in THF at room temperature afforded only the unexpected fused-heterocyclic compound 8,9-dibenzyl-3,14-dimethyl8a,9-dihydro-8H-benzo [4,5] a n u s c r i p t 32 silyl complexes were also found to react with 2,6-dimethylphenyl isocyanide to yield the metalla-azirine products and with carbodiimides to generate amidinate complexes (Scheme 44).…”