Unexpected Vulnerability of DPEphos to C-O Activation in the Presence of Nucleophilic Metal Hydrides

Mateusz Cybulski, Nicholas Beattie, Stuart Macgregor, Mary Mahon, Michael Whittlesey

Research output: Contribution to journalArticle

Abstract

C−O bond activation of DPEphos occurs upon mild heating in the presence of [Ru(NHC) 2(PPh 3) 2H 2] (NHC=N-heterocyclic carbene) to form phosphinophenolate products. When NHC=IEt 2Me 2, C−O activation is accompanied by C−N activation of an NHC ligand to yield a coordinated N-phosphino-functionalised carbene. DFT calculations define a nucleophilic mechanism in which a hydride ligand attacks the aryl carbon of the DPEphos C−O bond. This is promoted by the strongly donating NHC ligands which render a trans dihydride intermediate featuring highly nucleophilic hydride ligands accessible. C−O bond activation also occurs upon heating cis-[Ru(DPEphos) 2H 2]. DFT calculations suggest this reaction is promoted by the steric encumbrance associated with two bulky DPEphos ligands. Our observations that facile degradation of the DPEphos ligand via C−O bond activation is possible under relatively mild reaction conditions has potential ramifications for the use of this ligand in high-temperature catalysis.

Original languageEnglish
Pages (from-to)11141-11145
Number of pages5
JournalChemistry - A European Journal
Volume26
Early online date19 May 2020
DOIs
Publication statusPublished - 26 Aug 2020

Keywords

  • C−O bond activation
  • N-heterocyclic carbenes
  • density functional calculations
  • hydride ligands
  • phosphines

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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