Photochemically initiated oxidative carbon-carbon bond-cleavage reactivity in chlorodiketonate Ni II complexes

Caleb J. Allpress, Atta M. Arif, Dylan T. Houghton, Lisa M. Berreau

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Three mononuclear Ni II complexes containing a 2-chloro-1,3-diketonate ligand and supported by the 6-Ph 2TPA chelate, as well as analogues that lack the 2-chloro substituent on the β-diketonate ligand, have been prepared and characterized. Upon irradiation at 350 nm under aerobic conditions, complexes containing the 2-chloro-substituted ligands undergo reactions to generate products resulting from oxidative cleavage, α-cleavage, and radical-derived reactions involving the 2-chloro-1,3-diketonate ligand. Mechanistic studies suggest that the oxidative cleavage reactivity, which leads to the production of carboxylic acids, is a result of the formation of superoxide, which occurs through reaction of reduced nickel complexes with O 2. The presence of the 2-chloro substituent was found to be a prerequisite for oxidative carbon-carbon bond-cleavage reactivity, as complexes lacking this functional group did not undergo these reactions following prolonged irradiation. The approach toward investigating the oxidative reactivity of metal β-diketonate species outlined herein has yielded results of relevance to the proposed mechanistic pathways of metalloenzyme-catalyzed β-diketonate oxidative cleavage reactions.

Original languageEnglish (US)
Pages (from-to)14962-14973
Number of pages12
JournalChemistry - A European Journal
Volume17
Issue number52
DOIs
StatePublished - Dec 23 2011

Keywords

  • diketones
  • dioxygenase
  • iron
  • nickel
  • oxygen
  • redox chemistry
  • superoxides

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