from first principles PP-I-1

OP-II-2Living Olefin Polymerization with Post-Titanocene Catalysts Containingo-Fluoroaryl Substituents: Role of Noncovalent InteractionsTalsi E.P., Bryliakov K.P.Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russiabryliako@catalysis.ruTitanium(IV) complexes with bidentate N,O-donor ligands have attracted great attention ascatalysts for olefin polymerization, [1] especially with regard to their potential to induce livingpolymerization of ethylene, yielding PE with narrow molecular weight distributions (down toM w /M n 1.01 [2] ) and high molecular weights (M n 10 5 -10 6 g mol -1 ). The mechanisms responsiblefor living polymerization in the presence of o-fluorine substituents are still being debated.In this work, formation of ion-pair intermediates of the type [L 2 TiMe] + [MeMAO] - upon theinteraction of the titanium pre-catalysts L 2 TiCl 2 with methylalumoxane (MAO) has been followedby multinuclear NMR for various post-titanocene catalysts based on bis(salicylaldimine),bis(pyrrolylaldimine), and bis(enolatoimine) ligands. In some cases, propagating species of thetype [L 2 TiP] + [MeMAO] - (where P is the growing polymeryl chain) have been detected in thepresence of13 C-enriched ethylene, and characterized spectroscopically. [3] For thebis(enolatoimine) system, weak non-covalent interaction of the o-F substituents with the metalcenter in the active sites could be documented. This interaction is likely to trigger living olefinpolymerization by o-F substituted bis(enolatoimine) and structurally related Ti catalysts (viasuppression of β-hydrogen transfer and of chain transfer to AlMe 3 ), while catalysts without o-Fsubstituents do not exhibit living character.living systemCF 3non-living systemCF 3MeFOFFHNN Ti MeHC HF O CPolCFH 3free-chain, interacting-ligandThis work was supported by Russian Foundation for Basic Research, grant 12-03-00133.References:[1] (a) H. Makio, T. Fujita, Adv. Synth. Catal. 344 (2002) 477; (b) H. Makio, H. Terao, A. Iwashita,T. Fujita, Chem. Rev. 111 (2011) 2363.[2] S. M. Yu, S. Mecking, J. Am. Chem. Soc. 130 (2008) 13204.[3] (1) K. P. Bryliakov, E. A. Kravtsov, D. A. Pennington, S. J. Lancaster, M. Bochmann,H. H. Brintzinger, E. P. Talsi, Organometallics 24 (2005) 5660; (b) K. P. Bryliakov, E. P. Talsi,H. M. Möller, M. C. Baier, S. Mecking, Organometallics 29 (2010) 4428; (c) H. M. Möller,M. C. Baier, S. Mecking, E. P. Talsi, K. P. Bryliakov, Chem. Eur. J. 18 (2012) 848.37MeONN TiHHO CHCHCF 3Polinteracting-chainMe