Summary.
The iron(III) complex of indole-3-acetic acid (1) was prepared, and its physicochemical properties, mode of iron(III) coordination, and electronic structure were studied using UV/Vis, diffuse reflectance infrared Fourier transform (DRIFT), and transmission 57Fe Mössbauer spectroscopic techniques. The data obtained provide evidence that iron(III) is not only coordinated by the carboxylic O-donor atom, but also via the conjugated π-electronic system of the pyrrole moiety involving both the non-shared electronic pair of the heteroatom and the C(2)*C(3) double bond. Considering the well-known increased sensitivity of the pyrrole residue in indole derivatives to oxidation as compared to the benzene ring, as well as the formation of a triple complex (peroxidase-1-O2) proposed for the enzymatic 1 oxidative degradation mechanism involving as a key step the Fe3+ → Fe2+ transition in the enzyme form as discussed in literature, it is concluded that iron(III) coordination with 1 can influence the redox properties of the pyrrole ring by affecting its π-electronic system.
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Received September 17, 2000. Accepted (revised) October 31, 2000
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Kamnev, A., Shchelochkov, A., Tarantilis, P. et al. Complexation of Indole-3-acetic Acid with Iron(III): Influence of Coordination on the π-Electronic System of the Ligand. Monatshefte fuer Chemie 132, 675–681 (2001). https://doi.org/10.1007/s007060170081
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DOI: https://doi.org/10.1007/s007060170081