ISSN:
0947-6539
Schlagwort(e):
electronic structure
;
exchange coupling
;
heme proteins
;
iron complexes
;
porhyrins
;
Chemistry
;
General Chemistry
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
Notizen:
The molecular structure of the chloroiron(III) porphyrinate [FeIIICl- (tmtmp)] (1) is described. The doming off the bifacially encumbered tmtmp dianionic ligand present in 1 is characterized by a separation of 0.09 (1) Å between the mean plane of the four pyrrole nitrogens (4NP) and that of the porphyrin core. The coordination polyhedron of the five-coordinate iron atom is a square pyramid of C4v symmetry. The metal is displaced by 0.44 (1) Å from the 4Np mean plane towards the axial chloro ligand. The Fe-Np and Fe-Cl bond lengths are 2.057 (6) and 2.223(5) Å, respectively. Upon treatment of [FeIIITf(tmtmp)] (2) with m-chloroperoxybenzoic acid, the green oxoferryl π radical cation complex [FeIV=O(tmtmp)]+ (3) is obtained. It has been studied by EPR, Mössbauer, and resonance Raman spectroscopy. It exhibits an EPR spectrum strikingly similar to those of compounds I of Micrococcus lysodeikticus catalase (APX-I) and ascorbate peroxidase (APX-I) The exchange interactions between the spins of the radical cation and the ferryl iron are of the ferromagnetic type and are the weakest ever found for a synthetic compound I model. The shift of + 22 cm-1 in the radical marker band v2 in the resonance Raman spectra upon oxidation of 2 to 3 confirms that the electronic state of the porphyrin π radical cation is predominantly 2Alu in this tmtmp compound 1 model.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/chem.1460020917
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