Dinuclear copper-dioxygen intermediates supported by polyamine ligands

Shinichi Teramae, Takao Osako, Shigenori Nagatomo, Teizo Kitagawa, Shunichi Fukuzumi, Shinobu Itoh

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Reactivity of the dicopper(I) and dicopper(II) complexes supported by novel polyamine ligands L1 (1,11-bis(6-methylpyridin-2-yl)-2,6,10-triaza-2,6,10- tribenzylundecane) and L2 (5-benzyl-1,9-bis(6-methylpyridin-2-yl)-2,8-bis(6- methylpyridin-2-ylmethyl)-2,5,8-triazanonane) towards O2 and H 2O2, respectively, has been investigated in order to shed light on the ligand effects on Cu2/O2 chemistry. The dicopper(I) complex of L1 (1a) readily reacted with O2 in a 2:1 ratio at a low temperature (-94°C) in acetone to afford a mixture of (μ-η22-peroxo)dicopper(II) and bis(μ-oxo)dicopper(III) complexes. The formation of these species has been confirmed by the electron spin resonance (ESR) silence of the solution as well as their characteristic absorption bands in the UV-visible region [λmax=350 and 510 nm due to the peroxo complex and ∼400 nm due to the bis(μ-oxo) complex] and the resonance Raman bands at 729 cm -1 [Δν (16O2-18O 2) = 38 cm-1] due to the peroxo complex and at 611 and 571 cm-1 [Δν (16O2-18O 2) = 22 and 7 cm-1, respectively] due to the bis(μ-oxo) complex. The peroxo and bis(μ-oxo) complexes were unstable even at the low temperature, leading to oxidative N-dealkylation at the ligand framework. The dicopper(I) complex of L2 (2a) also reacted with O2 to give (μ-hydroxo)dicopper(II) complex (2bOH) as the product. In this case, however, no active oxygen intermediate was detected even at the low temperature (-94°C). With respect to the copper(II) complexes, treatment of the (μ-hydroxo)dicopper(II) complex of L1 (1bOH) with an equimolar amount of H2O2 in acetone at -80°C efficiently gave a (μ-1,1-hydroperoxo)dicopper(II) complex, the formation of which has been supported by its ESR-silence as well as UV-vis (370 and 650 nm) and resonance Raman spectra [881 cm-1; Δν (16O 2-18O2) = 49 cm-1]. The (μ-1,1-hydroperoxo)dicopper(II) intermediate of L1 also decomposed slowly at the low temperature to give similar oxidative N-dealkylation products. Kinetic studies on the oxidative N-dealkylation reactions have been performed to provide insight into the reactivity of the active oxygen intermediates.

Original languageEnglish
Pages (from-to)746-757
Number of pages12
JournalJournal of Inorganic Biochemistry
Issue number5
StatePublished - May 2004

Bibliographical note

Funding Information:
This work was financially supported in part by a Grants-in-Aid for Scientific Research on Priority Area (No. 11228206), Grants-in-Aids for Scientific Research (Nos. 13480189 and 15350105) from the Ministry of Education, Culture, Sports, Science and Technology, Japan, and also by Research Fellowships of Japan Society for the Promotion of Science for Young Scientists.


  • (μ-1,1-Hydroperoxo)dicopper(II) complex
  • (μ-η:η-Peroxo) dicopper(II) complex
  • Bis(μ-oxo) dicopper(III) complex
  • Dioxygen activation
  • Unsymmetrical dicopper complex


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