EPR monitoring of vanadium(IV) species formed upon activation of vanadium(V) polyphenolate precatalysts with AlR2Cl and AlR2Cl/ethyltrichloroacetate (R = Me, Et)

Soshnikov, Igor E., Semikolenova, Nina V., Shubin, Alexander A., Bryliakov, Konstantin P., Zakharov, Vladimir A., Redshaw, Carl ORCID: https://orcid.org/0000-0002-2090-1688 and Talsi, Evgenii P. (2009) EPR monitoring of vanadium(IV) species formed upon activation of vanadium(V) polyphenolate precatalysts with AlR2Cl and AlR2Cl/ethyltrichloroacetate (R = Me, Et). Organometallics, 28 (23). pp. 6714-6720. ISSN 1520-6041

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Abstract

Reactions of the vanadyl polyphenolate complexes {VO[p-tert-butylcalix[4]arene(O)3(OMe)]} ( 1 ) and [VO(OArCH2Ar'CH2OAr)]2 (Ar = 4,6-tert-butylphenol; Ar' = 4-tert-butylphenol) ( 2 ) with AlR3 and AlR2Cl, in the absence and in the presence of reactivator (ethyltrichloroacetate, ETA), were monitored by EPR (R = Me, Et). It was shown, that vanadium(IV) complexes with proposed structures L1VIVR(AlR3) and L1VIVR(AlR2Cl) are formed upon interaction of 1 with AlR3 and AlR2Cl, respectively (20 °C, L1 is the initial oxo-calix[4]arene ligand). Similarly, vanadium(IV) complexes with proposed structures L2VIVR(AlR3) and L2VIVR(AlR2Cl) are formed upon interaction of 2 with AlR3 and AlR2Cl (L2 is the initial ligand of 2 ). The growth of the concentration of L1VIVR(AlR2Cl) and L2VIVR(AlR2Cl) correlates with the increase of the ethylene polymerization activity of the catalyst systems 1 , 2 /AlR2Cl/ETA. It is proposed therefore that vanadium(IV) species of the type L1VIVR(AlR2Cl) and L2VIVR(AlR2Cl) can be the active species (or their immediate precursors) of the catalyst system 1 , 2 /AlR2Cl/ETA.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Chemistry (former - to 2024)
Depositing User:	Rachel Smith
Date Deposited:	29 Mar 2011 09:35
Last Modified:	18 Jun 2026 15:11
URI:	https://ueaeprints.uea.ac.uk/id/eprint/27173
DOI:	10.1021/om900515h

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