An EPR Study of the V(IV) Species Formed Upon Activation of a Vanadyl Phenoxyimine Polymerization Catalyst with AlR3 and AlR2Cl (R = Me, Et)
✍ Scribed by Igor E. Soshnikov; Nina V. Semikolenova; Konstantin P. Bryliakov; Alexander A. Shubin; Vladimir A. Zakharov; Carl Redshaw; Evgenii P. Talsi
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 239 KB
- Volume
- 210
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
Vanadium(IV) complexes formed in the systems L~2~V^IV^O/AlR~3~, L~2~V^IV^O/AlR~3~/ETA, L~2~V^IV^O/AlR~2~Cl, and L~2~V^IV^O/AlR~2~Cl/ETA, where L is a phenoxyimine ligand (Scheme 1), R = Me or Et, and ETA is ethyltrichloroacetate, were monitored by EPR. It was shown, that at 20 °C, V(IV) complexes with proposed structures (L′)V^IV^(O)(R)(AlR~3~) are formed in the systems L~2~V^IV^O/AlR~3~ and L~2~V^IV^O/AlR~3~/ETA, whereas complexes with proposed structures (L′)V^IV^(O)(R)(AlR~2~Cl) are formed in the systems L~2~V^IV^O/AlR~2~Cl and L~2~V^IV^O/AlR~2~Cl/ETA (L′ is the modified initial ligand). The systems L~2~V^IV^O/AlR~3~/ETA are inert towards polymerization of ethylene, whereas the systems L~2~V^IV^O/AlR~2~Cl/ETA are moderately active in this reaction. The polymerization activity of the systems L~2~V^IV^O/AlR~2~Cl/ETA correlates with the concentration of V(IV) species present in the reaction solution. V(IV) complexes of the type (L′)V^IV^(O)(R)(AlR~2~Cl) can be precursors of the active species of polymerization.
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