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Issue 9, 2008
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Probing the effects of ligand structure on activity and selectivity of Cr(iii) complexes for ethylene oligomerisation and polymerisation

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Abstract

A series of distorted octahedral Cr(III) complexes containing tridentate S-, S/O- or N-donor ligands comprised of three distinct architectures: facultative {S(CH2CH2SC10H21)2 (L1) and O(CH2CH2SC10H21)2 (L2)}, tripodal {MeC(CH2SnC4H9)3 (L3), MeC(CH2SC10H21)3 (L4)} and macrocyclic {(C10H21)[9]aneN3 (L5), (C10H21)3[9]aneN3 (L6), with [9]aneN3 = 1,4,7-triazacyclononane} are reported and characterised spectroscopically. Activation of [CrCl3(L)] with MMAO produces very active ethylene trimerisation, oligomerisation and polymerisation catalysts, with significant dependence of the product distribution upon the ligand type present. The properties of the parent [CrCl3(L)] complexes are probed by cyclic voltammetry, UV-visible, EPR, EXAFS and XANES measurements, and the effects upon activation with Me3Al investigated similarly. Treatment with excess Me3Al leads to substitution of Cl ligands by Me groups, generation of an EPR silent Cr species (consistent with a change in the oxidation state of the Cr to either Cr(II) or Cr(IV)) and substantial dissociation of the neutral S and S/O-donor ligands.

Graphical abstract: Probing the effects of ligand structure on activity and selectivity of Cr(iii) complexes for ethylene oligomerisation and polymerisation

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Article information


Submitted
17 Oct 2007
Accepted
30 Nov 2007
First published
03 Jan 2008

Dalton Trans., 2008, 1177-1185
Article type
Paper

Probing the effects of ligand structure on activity and selectivity of Cr(III) complexes for ethylene oligomerisation and polymerisation

J. O. Moulin, J. Evans, D. S. McGuinness, G. Reid, A. J. Rucklidge, R. P. Tooze and M. Tromp, Dalton Trans., 2008, 1177 DOI: 10.1039/B716078J

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