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

Sc(iii) complexes with neutral N3- and SNS-donor ligands – a spectroscopic study of the activation of ethene polymerisation catalysts
Sc(iii) complexes with neutral N3- and SNS-donor ligands – a spectroscopic study of the activation of ethene polymerisation catalysts
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.
0300-9246
2213-2223
Bartlett, Stuart A.
1adeb675-9e04-4635-bdb8-df3833333f34
Cibin, Giannantonio
61a833d3-097f-4817-bcd3-6b26cf42dbe5
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Evans, John
05890433-0155-49fe-a65d-38c90ea25c69
Hanton, Martin J.
589fd6f4-fcb3-44fe-b890-cb0289e31581
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Tooze, Robert P.
9461ecde-9da0-42c6-a17f-6387bd8c5a7b
Tromp, Moniek
a5da2bdf-9f4e-452a-8aa8-032e0c9b6660
Bartlett, Stuart A.
1adeb675-9e04-4635-bdb8-df3833333f34
Cibin, Giannantonio
61a833d3-097f-4817-bcd3-6b26cf42dbe5
Dent, Andrew J.
24c2a218-cb0e-4193-af0b-3ff1dc42b552
Evans, John
05890433-0155-49fe-a65d-38c90ea25c69
Hanton, Martin J.
589fd6f4-fcb3-44fe-b890-cb0289e31581
Reid, Gillian
37d35b11-40ce-48c5-a68e-f6ce04cd4037
Tooze, Robert P.
9461ecde-9da0-42c6-a17f-6387bd8c5a7b
Tromp, Moniek
a5da2bdf-9f4e-452a-8aa8-032e0c9b6660

Bartlett, Stuart A., Cibin, Giannantonio, Dent, Andrew J., Evans, John, Hanton, Martin J., Reid, Gillian, Tooze, Robert P. and Tromp, Moniek (2013) Sc(iii) complexes with neutral N3- and SNS-donor ligands – a spectroscopic study of the activation of ethene polymerisation catalysts. Dalton Transactions, 42 (6), 2213-2223. (doi:10.1039/c2dt31804k). (PMID:23192302)

Record type: Article

Abstract

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.

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e-pub ahead of print date: 15 November 2012
Published date: 2013
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow

Identifiers

Local EPrints ID: 351228
URI: https://eprints.soton.ac.uk/id/eprint/351228
ISSN: 0300-9246
PURE UUID: 9cbe5414-0cad-4399-8be0-b24dae917b8e
ORCID for Gillian Reid: ORCID iD orcid.org/0000-0001-5349-3468

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Date deposited: 16 Apr 2013 15:19
Last modified: 14 Jul 2018 00:37

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Contributors

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

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