Sigma-Noninnocence: Masked Phenyl-Cation Transfer at Formal Ni-IV

Jelte S. Steen, Gerald Knizia, Johannes E. M. N. Klein*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Reductive elimination is an elementary organometallic reaction step involving a formal oxidation state change of -2 at a transition-metal center. For a series of formal high-valent Ni-IV complexes, aryl-CF3 bond-forming reductive elimination was reported to occur readily (Bour et al. J. Am. Chem. Soc. 2015, 137, 8034-8037). We report a computational analysis of this reaction and find that, unexpectedly, the formal Ni-IV centers are better described as approaching a +II oxidation state, originating from highly covalent metal-ligand bonds, a phenomenon attributable to sigma-noninnocence. A direct consequence is that the elimination of aryl-CF3 products occurs in an essentially redox-neutral fashion, as opposed to a reductive elimination. This is supported by an electron flow analysis which shows that an anionic CF3 group is transferred to an electrophilic aryl group. The uncovered role of sigma-noninnocence in metal-ligand bonding, and of an essentially redox-neutral elimination as an elementary organometallic reaction step, may constitute concepts of broad relevance to organometallic chemistry.

Original languageEnglish
Pages (from-to)13133-13139
Number of pages7
JournalAngewandte Chemie-International Edition
Volume58
Issue number37
DOIs
Publication statusPublished - 9-Sep-2019

Keywords

  • coinage metals
  • homolysis
  • ligand-field inversion
  • radicals
  • trifluoromethyl
  • H BOND ACTIVATION
  • COORDINATION CHEMISTRY
  • OXIDATION-STATE
  • ALKYL-HALIDES
  • GROUND-STATE
  • METAL
  • COMPLEXES
  • LIGANDS
  • REACTIVITY
  • CATALYSIS

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