Structural and Functional Investigations on Diiron Complexes: Catalase-Like Activity and Mechanistic Studies on the Formation of (μ-Peroxo)diiron(III) Adducts
✍ Scribed by Roberto Than; Antje Schrodt; Lars Westerheide; Rudi van Eldik; Bernt Krebs
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 356 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-1948
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✦ Synopsis
The new diiron complex [Fe 2 (tbpo){O 2 As(CH 3 ) 2 }(CH 3 O)-hydroxo-bridged complex [Fe 2 (tbpo)(OH)(NO 3 ) 2 ](NO 3 ) 2 • CH 3 OH • 2 H 2 O (2) was employed. The reactions of 1 and 2
with H 2 O 2 were studied as a function of [H 2 O 2 ], pH, temperature, and pressure, and the kinetic results including using the heptadentate ligand N,N,NЈ,NЈ-Tetrakis(2benzimidazolylmethyl)-1,3-diamino-2-propanol (Htbpo). The the activation parameters are reported. In the case of compound 2 the reaction proceeds in one step, and the complex was characterized structurally by X-ray crystallography. 1 reproduces the coordination mode and the observed first order rate constant, k obs , shows a linear dependence on the hydrogen peroxide concentration with a stoichiometry of the proposed purple acid phosphatasearsenate inhibitor complex. More importantly, 1 is a good zero intercept. For complex 1 the kinetic traces could be fitted to two exponential functions. One of the observed functional model for the activation of small molecules, since the solvent molecule in the coordination sphere of each iron pseudo-first-order rate constants, k obs1 , exhibits a linear dependence on the hydrogen peroxide concentration with a ion can be substituted very easily by a small substrate molecule. This is confirmed by the comparatively high pH-zero intercept, whereas the other rate constant, k obs2, was independent of the hydrogen peroxide concentration. A dependent catalase-like activity of 1. In order to study the influence of the cacodylate bridge on the formation of the mechanistic interpretation is presented. metastable adduct with hydrogen peroxide, the analogous Recently, the structures of three dinuclear peroxo bridged [a] Anorganisch-