Synthesis, characterization, and reactivity of cobalt(III)-oxygen complexes bearing a macrocyclic N-tetramethylated cyclam ligand

Doyeon Kim, Jaeheung Cho, Yong Min Lee, Ritimukta Sarangi, Wonwoo Nam

Research output: Contribution to journalArticlepeer-review

24 Scopus citations

Abstract

Mononuclear metal-dioxygen species are key intermediates that are frequently observed in the catalytic cycles of dioxygen activation by metalloenzymes and their biomimetic compounds. In this work, a side-on cobalt-(III)-peroxo complex bearing a macrocyclic N-tetramethylated cyclam (TMC) ligand, [CoIII(15-TMC)(O2)]+, was synthesized and characterized with various spectroscopic methods. Upon protonation, this cobalt(III)-peroxo complex was cleanly converted into an end-on cobalt(III)-hydroperoxo complex, [CoIII(15-TMC)(OOH)]2+. The cobalt(III)-hydroperoxo complex was further converted to [CoIII(15-TMC-CH2-O)]2+ by hydroxylation of a methyl group of the 15-TMC ligand. Kinetic studies and 18 O-labeling experiments proposed that the aliphatic hydroxylation occurred via a CoIV-oxo (or CoIII-oxyl) species, which was formed by O-O bond homolysis of the cobalt(III)-hydroperoxo complex. In conclusion, we have shown the synthesis, structural and spectroscopic characterization, and reactivities of mono-nuclear cobalt complexes with peroxo, hydroperoxo, and oxo ligands.

Original languageEnglish
Pages (from-to)14112-14118
Number of pages7
JournalChemistry - A European Journal
Volume19
Issue number42
DOIs
StatePublished - 11 Oct 2013

Keywords

  • Aliphatic hydroxylation
  • Bioinorganic chemistry
  • Cobalt
  • Macrocyclic ligands
  • Oxygen

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