A bulky 1,4,7-triazacyclononane and acetonitrile, a Goldilocks system for probing the role of NiIII and NiI centers in cross-coupling catalysis

Leonel Griego, Ju Byeong Chae, Liviu M. Mirica

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

In nickel-catalyzed cross-coupling reactions involving alkyl substrates, catalysts supported by N-donor ligands are proposed to involve paramagnetic Ni(I) and Ni(III) species as key intermediates. Herein, we report the use of a bulky ligand, 1,4,7-triisopropyl-1,4,7-triazacyclononane (iPr3TACN), that facilitated the detection or isolation of uncommon organometallic Ni(I) and Ni(III) complexes involved in well-defined oxidative addition, transmetalation, and reductive elimination steps. Moreover, (iPr3TACN)Ni(II) complexes were shown to be efficient catalysts for alkyl-alkyl Kumada cross-coupling. The presence of acetonitrile and other alkyl nitriles led to an increased yield of cross-coupled products, and the multifaceted beneficial role of the nitrile additive during catalysis was thoroughly investigated. Overall, these studies provide unambiguous evidence for the involvement of both Ni(III) and Ni(I) organometallic species in Ni-catalyzed alkyl-alkyl cross-coupling reactions and suggest the presence of a coordinating solvent and a weak π-acceptor, such as acetonitrile, could have a beneficial effect for a range of Ni-mediated organometallic transformations.

Original languageEnglish
Pages (from-to)867-881
Number of pages15
JournalChem
Volume10
Issue number3
DOIs
StatePublished - Mar 14 2024

Keywords

  • Kumada cross-coupling
  • Ni(I) and Ni(III) complexes
  • SDG12: Responsible consumption and production
  • SDG3: Good health and well-being
  • electron paramagnetic resonance
  • organometallic Ni complexes
  • tridentate ligands

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