Magnetooptical and Structural Investigations of Five Dimeric Cobalt(II) Complexes Mimicking Metalloenzyme Active Sites

Four novel cobalt(II) complexes mimicking metalloenzyme active sites, novel C14H22Cl12Co2O13·2C3H8O (1), C28H36Cl24Co4O28·4C4H8O2 (2), C16H22Cl12Co2O13·C2HCl3O2 (3), C16H22Cl12Co2O13 (4), and one known C40H78Cl8Co2O17 (5) are composed of the same core of two high-spin cobalt(II) centers triply bridg...

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Bibliographic Details
Published in:Inorganic chemistry 2012-06, Vol.51 (11), p.6046-6055
Main Authors: Tomkowicz, Z, Ostrovsky, S, Foro, S, Calvo-Perez, V, Haase, W
Format: Article
Language:English
Subjects:
Biomimetic Materials - chemistry
Catalytic Domain
Circular Dichroism
Cobalt - chemistry
Coordination Complexes - chemistry
Crystallography, X-Ray
Magnetics
Metalloproteins - chemistry
Models, Molecular
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Summary:Four novel cobalt(II) complexes mimicking metalloenzyme active sites, novel C14H22Cl12Co2O13·2C3H8O (1), C28H36Cl24Co4O28·4C4H8O2 (2), C16H22Cl12Co2O13·C2HCl3O2 (3), C16H22Cl12Co2O13 (4), and one known C40H78Cl8Co2O17 (5) are composed of the same core of two high-spin cobalt(II) centers triply bridged by water and two trichloroacetato (1–4) or two pivalate (5) groups but differ in terminal ligands. The crystal structures of new compounds 1–4 belong to the space groups P1̅, P21/c, P1̅, and Pbcn, respectively. All five investigated complexes contain Co atoms in distorted octahedral coordination. The complexes were characterized by magnetic susceptibility and magnetization measurements and by variable-temperature variable-field magnetic circular dichroism spectroscopy. Experimental data were analyzed in the frame of the theoretical model, which includes an unquenched orbital moment of the CoII ions. All investigated compounds are antiferromagnetically coupled with exchange constants in the range −1.5 to −2.1 cm–1. However, there is a significant difference between the crystal-field-splitting parameters.
ISSN:0020-1669
1520-510X
DOI:10.1021/ic202529p