Spectroscopic study of a bis(imidazole)(octaethylporphyrinato)iron(III) complex

Low-spin ferric octaethylporphyrinatoiron complex with two imidazole axial ligands [Fe(III)(OEP)(Im)_{2}]^{+} has been investigated by electron paramagnetic resonance (EPR) and Mossbauer spectroscopies. It was found that the ground spin state corresponds to the electron configuration (dxy)^{2} (dxz, dyz)^{3} and planes of the imidazole axial ligands have a parallel mutual orientation. Ethyl groups bonded to pyrrole rings, as peripheral substituents, effect on the ground electron spin state of the complex studied and the relative orientation of the the imidazole axial ligands in a similar way like the phenyl substituents bonded to meso-carbon atoms of the porphyrin macrocycle. The temperature dependence of the Mossbauer spectra is discussed in terms of magnetic relaxation processes

Mössbauer study of a tetrakis (pentafluorophenyl) porphyrin iron (III) chloride in comparison with the fluorine unsubstituted analogue

Mossbauer investigations, in association with density functional theory (DFT) calculations, have been conducted for the molecular and electronic structures of iron (III) [tetrakis (pentafluorophenyl)] porphyrin chloride [(F_{20}TPP)Fe:Cl], as a Fe(III)-tetraphenylporphyrin complex containing chloride axial ligand and substituted hydrogen atoms by fluorine ones in the four phenyl rings, in comparison with its fluorine unsubstituted analogue [(TPP)Fe:Cl]. It was found that the parameters of Mossbauer spectra of both complexes are close to one another, and correspond to the high-spin state of Fe(III) ions, but they show the different temperature dependence and the quadrupole doublets in Mossbauer spectra show different asymmetry at low temperatures. Results of DFT calculations are analyzed in the light of catalytic activity of the halogenated complex