Synthesis and characterization of three mononuclear Fe(III) complexes containing bipodal and tripodal ligands: X-ray molecular structure of the dichloro[N-propanamide-N,N-bis-(2-pyridylmethyl)amine]iron(III) perchlorate |
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Authors: | Naké dia M.F. Carvalho,Adailton J. Bortoluzzi,O.A.C. Antunes |
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Affiliation: | a Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária CT Bloco A-641, Rio de Janeiro 21945-970, RJ, Brazil b Laboratório de Ciências Químicas, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, 28013-600, RJ, Brazil c Departamento de Química, Universidade Federal de Santa Catarina, Florianópolis 88040-900, SC, Brazil d Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis 88040-900, SC, Brazil |
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Abstract: | In this work, we present the synthesis and characterization of three mononuclear iron(III) complexes: dichloro[N-propanamide-N,N-bis-(2-pyridylmethyl)amine]iron(III) perchlorate (1), trichloro[N-methylpropanoate-N,N-bis-(2-pyridylmethyl)amine]iron(III) (2) and trichloro[bis-(2-pyridylmethyl)amine]iron(III) (3). The complexes were characterized by cyclic voltammetry, conductivimetry, elemental analyses, and by electronic, infrared and Mössbauer spectroscopies. Complex 1 was also characterized by X-ray structural analysis, which showed an iron center coordinated to one amide, one tertiary amine, two pyridine groups and two chloride ions. While for 1 the X-ray molecular structure and the infrared spectrum confirm the coordination of the amide group by the oxygen atom, the infrared spectrum of 2 indicates that the ester group present in the ligand is not coordinated, resulting in a N3Cl3 donor set, similar to the one present in 3. However, in 3 there is a secondary amine while in 2 a tertiary amine exists. These structural differences result in distinguishable variations in the Lewis acidity of the iron center, which could be evaluated by the analysis of the redox potential of the complexes, as well as by Mössbauer parameters. Thus, the Lewis acidity decreases in the following order: 1 > 2 > 3. It is important to notice that 1 has the amide group coordinated to the iron center, a feature present in metalloenzymes as lipoxygenase and isopenicillin N synthase, and in a small number of mononuclear iron(III) complexes. |
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Keywords: | Iron complexes Bis(2-pyridylmethyl)amine-derivative ligands Crystal structure Lewis acidity Mö ssbauer spectroscopy |
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