Journalartikel

Autorenliste: Hazell, A; McKenzie, CJ; Nielsen, LP; Schindler, S; Weitzer, M

Jahr der Veröffentlichung: 2002

Seiten: 310-317

Zeitschrift: Journal of the Chemical Society. Dalton transactions

Bandnummer: 2002

Heftnummer: 3

ISSN: 1472-7773

DOI Link: https://doi.org/10.1039/b103844n

Verlag: Royal Society of Chemistry

Abstract: 
A series of transient interconvertible protonated and deprotonated mononuclear Fe(III) peroxo species are derived from the pH dependent reaction of dihydrogen peroxide with mononuclear iron(II) or iron(III) complexes of general formulation [Fe(Rtpen)X](A)(n), n = 1, 2; X = Cl, Br; Rtpen = N-alkyl-N,N',N'-tris(2-pyridylmethyl) ethane- 1,2-diamine, alkyl = R = CH3CH2, CH3CH2CH2, HOCH2CH2, (CH3)(2)CH, C6H5, and C6H5CH2; A = ClO4, PF6. The low-spin iron(III) hydroperoxide complex ions [Fe(Rtpen)(eta(1)-OOH)](2+) are purple chromophores and the high-spin iron(III) peroxide complexes, [Fe(Rtpen)(eta(2)-OO)](+) are blue chromophores. The spectroscopic observation (ESR, UV-vis, ESI MS) of a low-spin iron(III) precursor species [Fe(Rtpen)(eta(1)-OCH3)](2+) and kinetic studies show that formation of [Fe(Rtpen)(eta(1)-OOH)](2+) from iron(II) solution species is a two step process. The first step, the oxidation of the iron(II) complex to [Fe(Rtpen)(OCH3)](2+), is faster than the subsequent ligand substitution during which [Fe( Rtpen) ( eta(1)-OOH)](2+) is formed. The kinetic data are consistent with an interchange associative mechanism for the ligand substitution, and a role for the proton bound to the uncoordinated hydroperoxide oxygen atom is suggested. The stability of [Fe(Rtpen)(eta(1)-OOH)](2+) R = HOCH2CH2, is significantly lower than for the peroxide complexes generated from the other alkyl substituted ligands (t(1/2) ca. 10 min vs. several hours). Tandem MS/MS experiments with the [Fe(Rtpen)(eta(1)-OOH)](2+) ions show fragmentation via O-O cleavage to give the novel ferryl species [Fe(Rtpen)(O)](2+). By contrast the [Fe(Rtpen)(eta(2)-OO)](+) ions are stable under the same gas phase conditions. This indicates a weaker O-O bond in the Fe(III) hydroperoxide complex ions, and that [(FeOOH)-O-III](2+) rather than [(FeOO)-O-III](+) species are the precursors to, at least, the ferryl Fe-IV=O species. Crystal structures of four starting iron(II) compounds, [Fe(Rtpen)Cl]PF6, R = HOCH2CH2, CH3CH2CH2, C6H5CH2, and [Fe(bztpen)Br]PF6 show the iron atoms in distorted octahedral geometries with pentadentate Rtpen coordination with the halide ion as the sixth ligand. The structure of [Fe(etOHtpen)Cl]PF6 shows an intermolecular H-bonding interaction between the dangling hydroxyethyl group and the chloride of a neighbouring molecule with O-H...Cl, 3.219(2) Angstrom.

Harvard-Zitierstil: Hazell, A., McKenzie, C., Nielsen, L., Schindler, S. and Weitzer, M. (2002) Mononuclear non-heme iron(III) peroxide complexes: syntheses, characterisation, mass spectrometric and kinetic studies, Journal of the Chemical Society. Dalton transactions, 2002(3), pp. 310-317. https://doi.org/10.1039/b103844n

APA-Zitierstil: Hazell, A., McKenzie, C., Nielsen, L., Schindler, S., & Weitzer, M. (2002). Mononuclear non-heme iron(III) peroxide complexes: syntheses, characterisation, mass spectrometric and kinetic studies. Journal of the Chemical Society. Dalton transactions. 2002(3), 310-317. https://doi.org/10.1039/b103844n