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RESEARCH PRODUCT

The heterodinuclear iron(III) and copper(II) molecule Cu(salen)Fe(acac)2NO3 and its iron precursor Fe(acac)2NO3. Synthesis, magnetic susceptibility, EPR and Mössbauer investigations

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Abstract The synthesis, EPR, magnetic and Mossbauer properties of two iron(III) complexes are reported. The heterodinuclear iron(III)-copper(II) complex Cu(salen)Fe(acac)2NO3 is obtained as an adduct from the reaction of the two mononuclear moieties, the Cu(salen) molecule and the mononuclear iron(III) molecule Fe(acac)2NO3 acting as a precursor of the dinuclear unit. The latter molecule itself has been prepared by ligand substitution from the tris-acetylacetonate Fe(acac)3. The dinuclear complex is characterized by comparing the properties of the mono- and the dinuclear complex. Fe(acac)2NO3 is identified from its typical IR spectrum with the main nitrate vibrations at 1380, 1250 and 1010 cm−1 and an axial S=5/2 EPR spectrum in the solid state. Ligand rearrangement occurs in solution as indicated by the presence of only ionic nitrate and a rhombic EPR spectrum. The dinuclear molecule presents a very modified IR spectrum, where the copper(salen) phenolic oxygen vibration and the bound-nitrate vibrations have disappeared; additionally no EPR spectrum can be recorded at X-band frequency. The magnetic data have been interpreted using spin-Hamiltonian formalism. From magnetic susceptibility measurements, in the solid state, the following set of parameters has been determined: g=1.99, D=4.15 cm−1 for the mononuclear complex, and J=−3 cm−1, g=2.05, D=−0.1 cm−1 for the dinuclear complex, indicating an effective antiferromagnetic interaction between the two metal ions. The Mossbauer studies yield: D=0.45 cm−1 for the mononuclear complex, and J=−1.5 cm−1, D=−0.20 cm−1 for the dinuclear complex.