Furan- and thiophene-functionalised bis-carbene ligands: Synthesis, silver(I) complexes, and catalysis

DJ Nielsen, KJ Cavell, MS Viciu, Steven Patrick Nolan, BW Skelton, AH White

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)

Abstract

New furan- and thiophene-functionalised nucleophilic heterocyclic carbene (NHC) complexes of Ag(I) were prepared via the reaction of novel furan- and thiophene-functionalised bis-imidazolium salts with Ag2O. Samples of both the N-methyl substituted furan- and thiophene-functionalised Ag(l) complexes suitable for single crystal X-ray studies were obtained following anion metathesis to the tetrafluoroborate salts. The structural characterisations revealed dinuclear [Ag-2(MeCEC)(2)](BF4)(2) (E = O, S) formulations with discrete twenty-membered dimetallacycles present in both instances; however, the overall molecular conformation varies considerably, notably in the orientations of the two bridging furan or thiophene heterocycles to the silver coordination plane. The functionalised bis-imidazolium salts were tested as in situ additives in a Pd(O)-catalysed aryl amination coupling reaction, with the best observed activities around 20% of those seen with 1,3-bis(2,6-di-iso-propylphenyl)imidazolium chloride under identical conditions. The bulkier N-'Bu and N-mesityl substituted salts were found to be more active than the N-methyl substituted analogues. (c) 2005 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)6133-6142
Number of pages10
JournalJournal of Organometallic Chemistry
Volume690
Issue number24-25
DOIs
Publication statusPublished - 1 Dec 2005

Keywords

  • imidazolium salts
  • functionalised
  • NHC
  • silver carbenes
  • X-ray structures
  • amination
  • N-HETEROCYCLIC CARBENES
  • PALLADIUM(II) COMPLEXES
  • STRUCTURAL-CHARACTERIZATION
  • LINKED CYCLOPHANE
  • SOLVENTS

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