Bis(μ-alkoxo)-bridged Dinuclear Iron(III) Complexes of Pyrazole-based Ligands as Models for Iron-oxo Proteins

Abstract

The synthesis and characterization of two new bis(μ-alkoxo)-bridged dinuclear iron(III) complexes with the ligands 1-(2-hydroxyethyl)-pyrazole (Hnhep) and 1-(2-hydroxyethyl)-3,5-dimethylpyrazole (Hnhed), [Fe(nhep)Cl2(EtOH)]2 (1) and [Fe(nhed)Cl2]2 (2) are reported. The crystal structures of both complexes reveal the presence of centrosymmetric dinuclear units. In compound 1, the iron(III) center has a coordination number of six, with a slightly distorted octahedral geometry. In compound 2, the bulkier nhed ligand, with methyl groups at the 3- and 5-positions of the pyrazole ring, leads to a coordination number of five at the iron(III) center in a distorted square pyramidal geometry. The magnetic properties of both complexes have been investigated in the range 2-300 K and indicate the presence of fairly weak antiferromagnetic exchange interactions between iron(III) ions (J1 = −10.04 cm−1 for 1 and J2 = −12.5 cm−1 for 2). The inactivity of both complexes in the cyclohexane hydroxylation appears to be partly due to the presence of the strong iron(III)-chloride bond that does not allow exchange with the reactant molecules.

Department(s)

Chemistry

Sponsor(s)

Dutch economy, ecology, and technology program

Keywords and Phrases

Iron; Pyrazoles

International Standard Serial Number (ISSN)

0277-5387

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2005 Elsevier, All rights reserved.

Publication Date

01 Jan 2005

Link to Full Text

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