engleski

EPR Study on Heterometallic (Cu2+ and Cr3+) Complex

The new heterometallic complex [Cu(bpy)3]2[Cr(C2O4)3]NO3∙ 9H2O, where bpy stands for 2, 2'-bipyridine has been synthesized in 2005 at the Ruđer Bošković Institute as a result of a wider study on a new possible class of molecule-based ferromagnetic material [1]. A single crystal of the prepared sample has been studied by electron paramagnetic resonance (EPR) at microwave frequency ν ≈ 9.6 GHz. The crystal was rotated round three arbitrary mutually perpendicular axes and EPR spectra were recorded at room temperature. The observed spectra exhibit two types of paramagnetic species: Cu2+ center with S = 1/2 and Cr3+ center with S = 3/2. In the examined frequency range, only transition for Cr3+ has been observed. By using computer simulation program following spin Hamiltonian parameters: for Cu2+ and , , and (angle between magnetic z axis and crystallographic b axis) approximately for Cr3+ have been deduced. The obtained parameters exhibit nearly the same structure in the wide temperature interval (5K to 300K) confirming absence of significant antiferromagnetic or ferromagnetic coupling between these centers.

EPR; Cu2+; Cr3+

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