Dft investigation of the 'quasi-living' propene polymerisation with Cp*TiMe3/b(C6F5)(3): the 'naked cation' approach

Sassmannshausen, J. (2009) Dft investigation of the 'quasi-living' propene polymerisation with Cp*TiMe3/b(C6F5)(3): the 'naked cation' approach. Dalton Transactions (41). pp. 8993-8999. ISSN 1472-7773

Abstract

Some time ago we reported the quasi-living polymerization of propene with the catalytic mixture of Cp*TiMe3 and B(C6F5)3 (Cp* = C5Me5). Surprisingly, this mixture is extremely sensitive towards the nature of the anion and the presence of aluminium alkyl. This intriguing observation led us to the attempt to unearth the underlying reaction mechanism using a computational approach. In this communication, we are reporting the first results with the naked cation approach. We obtained evidence, that the 1,2 insertion is the predominant reaction pathway. Whereas initial 1,2 and 2,1 insertion barriers are comparable, consequent second insertion is more discriminating between the two. Although we obtained evidence for the formation of -H agostic bonds, we found that -H elimination is a rare event due to the rather high activation barrier. We can conclude that the quasi-living polymerisation is at least partly an intrinsic property of the cation.

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