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Sc(III) complexes with neutral N-3- and SNS-donor ligands - a spectroscopic study of the activation of ethene polymerisation catalysts

Bartlett, S. A., Cibin, G., Dent, A. J., Evans, J., Hanton, M. J., Reid, G., Tooze, R. P. & Tromp, M., 2013, In : Dalton Transactions. 42, 6, p. 2213-2223 11 p.

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  • Sc(iii) complexes with neutral N3- and SNS-donor ligands – a spectroscopic study of the activation

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DOI

  • Stuart A. Bartlett
  • Giannantonio Cibin
  • Andrew J. Dent
  • John Evans
  • Martin J. Hanton
  • Gillian Reid
  • Robert P. Tooze
  • Moniek Tromp

Scandium trichloride complexes with tridentate N-3- and S2N-donor ligands (L-3) have been synthesised and characterised by IR, H-1, C-13{H-1} and Sc-45 NMR spectroscopy, microanalysis, and solid state and solution XAFS spectroscopy. Catalytic testing of a subset of these complexes with ethene has been undertaken in chlorobenzene with MMAO-3A and PMAO-IP at 60 degrees C and 40 bar ethene, giving low activity ethene polymerisation. The reactions of these complexes with MeLi and AlMe3 were studied by H-1, C-13{H-1}, Al-27 and Sc-45 NMR spectroscopy and in situ via Sc K-edge XAFS spectroscopy. Three or four mol. equivalents of MeLi react with [ScCl3(Me-3-tacn)] in THF solution to form [ScMe3(Me-3-tacn)] cleanly, while complexes of type [ScCl3(R-SNS)] {R-SNS = HN(CH2CH2SC10H21)(2)} form two different species proposed to be [ScMe3(R-SN(Li)S)] and [ScMe2(R-SN-S)]. In contrast, in situ Sc-45 NMR and Sc K-edge XAFS spectroscopic studies of the reaction of [ScCl3(Me-3-tacn)] with 10 mol. equivalents of AlMe3 strongly suggest that alkylation at the Sc(III) centre does not occur, instead retaining the Cl3N3 coordination environment and most likely forming Sc-Cl-AlMe3 bridging interactions. Similar studies on [ScCl3(decyl-SNS)] with 10 mol. equivalents of AlMe3 are also consistent with this, indicating that alkylation at the Sc centre does not occur except in the presence of co-catalyst [Ph3C][Al{OC(CF3)(3)}(4)] and the alpha-alkene, hex-1-ene.

Original languageEnglish
Pages (from-to)2213-2223
Number of pages11
JournalDalton Transactions
Volume42
Issue number6
Publication statusPublished - 2013
Externally publishedYes

    Keywords

  • ETHYLENE TRIMERIZATION, AQUEOUS-SOLUTION, SCANDIUM, YTTRIUM, REACTIVITY, CHEMISTRY, HYDRATION, CRYSTAL, HYDRIDE, ALKYL

ID: 107576067