Monitoring structure and valence state of chromium sites during catalyst formation and ethylene oligomerization by in situ EPR spectroscopy

Angelika Brueckner*, K. Jabor Jabor, Ann E. C. McConnell, Paul B. Webb

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

61 Citations (Scopus)

Abstract

For the first time, a Cr(acac)3/PNP mixture (PNP = Ph2PN(i-Pr)PPh2) and a [(PNP)CrC12(,U-CI)12 complex were monitored by in situ EPR in cyclohexane and toluene, respectively, during oligomerization of ethylene. For Cr(acac)3/PNP, Cr 3 + reduction is faster than low-spin Cr+ formation, suggesting that the major active species is EPR-silent, possibly an antiferromagnetic Cr+ dimer and/or Cr 21 Fast decomposition of [(PNP)CrC12(U-CI)12 to [Cr07 6 -CH3C6H5)21-+- is a probable reason for low activity.

Original languageEnglish
Pages (from-to)3849-3856
Number of pages8
JournalOrganometallics
Volume27
Issue number15
DOIs
Publication statusPublished - 11 Aug 2008

Keywords

  • TETRAMERIZATION
  • TRIMERIZATION
  • COMPLEXES
  • ACTIVATION
  • PHOSPHINE
  • OLEFIN
  • LIGAND

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