μ-η22-peroxodicopper(II) complex with a secondary diamine ligand: A functional model of tyrosinase

Liviu M. Mirica, Deanne Jackson Rudd, Michael A. Vance, Edward I. Solomon, Keith O. Hodgson, Britt Hedman, T. Daniel P. Stack

Research output: Contribution to journalArticlepeer-review

Abstract

The activation of dioxygen (O2) by Cu(I) complexes is an important process in biological systems and industrial applications. In tyrosinase, a binuclear copper enzyme, a μ-η2: η2-peroxodicopper(II) species is accepted generally to be the active oxidant. Reported here is the characterization and reactivity of a μ-η22-peroxodicopper(II) complex synthesized by reacting the Cu(I) complex of the secondary diamine ligand N,N′-di-tert-butyl-ethylenediamine (DBED), [(DBED)Cu(MeCN)](X) (1·X, X = CF3SO3, CH3SO3 -, SbF6-, BF4-), with O2 at 193 K to give [{Cu(DBED)}2(O2)](X) 2 (2·X2). The UV-vis and resonance Raman spectroscopic features of 2 vary with the counteranion employed yet are invariant with change of solvent. These results implicate an intimate interaction of the counteranions with the Cu2O2 core. Such interactions are supported further by extended X-ray absorption fine structure (EXAFS) analyses of solutions that reveal weak copper-counteranion interactions. The accessibility of the Cu2O2 core to exogenous ligands such as these counteranions is manifest further in the reactivity of 2 with externally added substrates. Most notable is the hydroxylation reactivity with phenolates to give catechol and quinone products. Thus the strategy of using simple bidentate ligands at low temperatures provides not only spectroscopic models of tyrosinase but also functional models.

Original languageEnglish (US)
Pages (from-to)2654-2665
Number of pages12
JournalJournal of the American Chemical Society
Volume128
Issue number8
DOIs
StatePublished - Mar 1 2006
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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