Interaction between peroxide ion and phenol group which are coordinated to the same iron(III) ion

Sayo Ito, Yoshihiro Ishikawa, Satoshi Nishino, Teruyuki Kobayashi, Shigeru Ohba, Yuzo Nishida

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

We have prepared several new iron(III) complexes with ligands which contain a phenol group; these are tetradentate [(X-phpy)H, X and H(phpy) represent the substituents on the phenol ring and N,N-bis(2-pyridylmethyl)-N-(2-hydroxybenzyl)amine, respectively] and pentadentate ligands [(R-enph-X)H; R=ethyl(Et) or methyl(Me) derivative and H(Me-enph) denotes N,N-bis(2-pyridylmethyl)-N″-methyl-N″-(2″-hydroxyl- benzylamine)ethylenediamine] and have determined the crystal structures of Fe(phpy)Cl2, Fe(5-NO2-phpy)Cl2, and Fe(Me-enph)ClPF6, which are of a mononuclear six-coordinate iron(III) complex with coordination of one or two chloride ion(s). These compounds are highly colored (dark violet) due to the coordination of phenol group to an iron(III) atom. When hydrogen peroxide was added to the solution of the iron(III) complex, a color change occurs with bleaching of the violet color, indicating that oxidative degradation of the phenol moiety occurred in the ligand system. The bleaching of the violet color was also observed by the addition of t-butylhydroperoxide. The rate of the disappearance of the violet color is highly dependent on the substituent on the phenol ring; introduction of an electron-withdrawing group in the phenol ring decreases the rate of bleaching, suggesting that disappearance of the violet band should be due to a chemical reaction between the phenol group and a peroxide adduct of the iron(III) species with an η1-coordination mode and that in this reaction the peroxide adduct acts as an electrophile towards phenol ring. The intramolecular interaction between the phenol moiety and an iron(III)-peroxide adduct may induce activation of the peroxide ion, and this was supported by several facts that the solution containing an iron(III) complex and hydrogen peroxide exhibits high activities for degradation of nucleosides and albumin.

Original languageEnglish
Pages (from-to)4379-4391
Number of pages13
JournalPolyhedron
Volume17
Issue number25-26
DOIs
Publication statusPublished - 1998 Nov 27

Keywords

  • Activation of peroxide
  • Degradation of albumin
  • Degradation of nucleoside
  • Interaction of peroxide ion and phenol group
  • Iron(III)-peroxide adduct

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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