Статья

A Tetracopper(II)-Tetraradical Cuboidal Core and Its Reactivity as a Functional Model of Phenoxazinone Synthase

Chandan MukherjeeInstitute for Inorganic and Analytical Chemistry, University of Mainz, D-55128 Mainz, Germany, and Max-Planck-Institute for Bioinorganic Chemistry, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, GermanyThomas WeyhermüllerInstitute for Inorganic and Analytical Chemistry, University of Mainz, D-55128 Mainz, Germany, and Max-Planck-Institute for Bioinorganic Chemistry, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, GermanyE. BotheInstitute for Inorganic and Analytical Chemistry, University of Mainz, D-55128 Mainz, Germany, and Max-Planck-Institute for Bioinorganic Chemistry, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, GermanyEva RentschlerInstitute for Inorganic and Analytical Chemistry, University of Mainz, D-55128 Mainz, Germany, and Max-Planck-Institute for Bioinorganic Chemistry, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, GermanyPhalguni ChaudhuriInstitute for Inorganic and Analytical Chemistry, University of Mainz, D-55128 Mainz, Germany, and Max-Planck-Institute for Bioinorganic Chemistry, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany

2007en

ABI

Аннотация

The coordination chemistry of the tridentate ligand N-(2-hydroxy-3,5-di-tert-butylphenyl)-2-aminobenzylalcohol H3L has been studied with the copper(II) ion. The ligand is noninnocent in the sense that it is readily oxidized in the presence of air to its o-iminobenzosemiquinonato [L*]2- radical form. The crystal structure of the synthesized tetracopper(II)-tetraradical complex [CuII4(L*)4] (1), has been determined by X-ray crystallography at 100 K. Variable-temperature (2-290 K) magnetic susceptibility measurements of complex 1 containing eight paramagnetic centers establish the spin ground state to be diamagnetic (St=0) arising from the antiferromagnetic interactions. Electrochemical measurements (cyclic voltammograms and square wave voltammograms) indicate four one-electron reductions of the ligand prior to the reduction of the metal center. Complex 1 is found to catalyze the aerial oxidation of 2-aminophenol to 2-amino-phenoxazine-3-one, thus modeling the catalytic function of the copper-containing enzyme phenoxazinone synthase. Kinetic measurements together with electron paramagnetic resonance and electronic spectral studies have been used to decipher the complex six-electron oxidative coupling of 2-aminophenol. An "on-off" mechanism of the radicals together with redox participation of the metal center is proposed for the catalytic oxidation processes.

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Идентификаторы

DOI: 10.1021/ic7012599

Цитирования и источники

Цитирований: 3Использованных источников: 0

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