Oxidation of first-row bivalent transition-metal complexes containing ethylenediaminetetra-acetate and nitrilotriacetate ligands by free radicals: A pulse-radiolysis study

Joseph Lati, Dan Meyerstein

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110 Scopus citations

Abstract

The kinetics of reaction of OH radicals with the ligands (L) ethylenediaminetetra-acetate (edta) and nitrilotriacetate (nta), and their complexes [ML] (M = ZnII, CuII, NiII, CoII, FeII, and MnII), have been studied. All these reactions have similar rate constants, although a hydrogen-abstraction reaction from the ligand is observed for the free ligands and their complexes with ZnII, MnII, and CoII. For [Co(edta)]2- a partial oxidation to [Co(edta)]- is observed. On the other hand, when M = NiII, CuII, or FeII the metal is oxidized by the OH radicals. The reasons for these observations are discussed in detail. The spectra, and kinetics of decomposition, of the unstable intermediates formed by the reactions of the OH radicals are reported and discussed. The reactions of nickel(III) complexes with I-, Br-, and O2 are reported. The kinetics of oxidation of the complexes (M = FeII, MnII, or CoII) by [O2]-., .O2CH2CMe2OH, [Br2]-., [(NCS)2]-., and [I2]-., the latter only with M = FeII, have also been studied. The kinetics indicate an inner-sphere mechanism for these reactions. The kinetics of hydrolysis of [MnIIIL(X)] and [CoIIIL(X)] thus formed are reported.

Original languageEnglish
Pages (from-to)1105-1118
Number of pages14
JournalJournal of the Chemical Society. Dalton Transactions
Issue number9
DOIs
StatePublished - 1 Dec 1978

ASJC Scopus subject areas

  • Chemistry (all)

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