Bis(phenoxy-imine)Ti catalysts with ortho-F-substituted phenyl rings on the N can promote living propene polymerization. On the basis of DFT calculations, it has been proposed that the “living” behavior originates from an unprecedented attractive interaction between the aforesaid ortho-F atoms and a β-H of the growing polymer chain, which would render the latter less prone to being transferred to the metal and/or to the monomer. In this paper, we report on a thorough full-QM and combined QM/MM investigation of representative model catalysts, demonstrating that the key factor is instead the repulsive nonbonded contact of the F-substituted rings with the growing polymer chain and an incoming propene molecule, which destabilizes the sterically demanding 6-center transition structure for chain transfer to the monomer. A conceptually similar substituent effect has been reported before for several metallocene and nonmetallocene catalysts.

Living Propene Polymerization with Bis(phenoxy-imine) Group 4 Metal Catalysts: A Theoretical Study / Talarico, Giovanni; Busico, Vincenzo; L., Cavallo. - In: KINETICS AND CATALYSIS. - ISSN 0023-1584. - STAMPA. - 47:(2006), pp. 289-294. [10.1134/s0023158406020212]

Living Propene Polymerization with Bis(phenoxy-imine) Group 4 Metal Catalysts: A Theoretical Study

TALARICO, GIOVANNI
;
2006

Abstract

Bis(phenoxy-imine)Ti catalysts with ortho-F-substituted phenyl rings on the N can promote living propene polymerization. On the basis of DFT calculations, it has been proposed that the “living” behavior originates from an unprecedented attractive interaction between the aforesaid ortho-F atoms and a β-H of the growing polymer chain, which would render the latter less prone to being transferred to the metal and/or to the monomer. In this paper, we report on a thorough full-QM and combined QM/MM investigation of representative model catalysts, demonstrating that the key factor is instead the repulsive nonbonded contact of the F-substituted rings with the growing polymer chain and an incoming propene molecule, which destabilizes the sterically demanding 6-center transition structure for chain transfer to the monomer. A conceptually similar substituent effect has been reported before for several metallocene and nonmetallocene catalysts.
2006
Living Propene Polymerization with Bis(phenoxy-imine) Group 4 Metal Catalysts: A Theoretical Study / Talarico, Giovanni; Busico, Vincenzo; L., Cavallo. - In: KINETICS AND CATALYSIS. - ISSN 0023-1584. - STAMPA. - 47:(2006), pp. 289-294. [10.1134/s0023158406020212]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11588/112038
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