Département de chimie moléculaire

This tutorial is dedicated to the investigation of magnetic anisotropy using both ESR (EPR) spectroscopy for its exptl. detn. and quantum chem. for its theor. prediction. Such an approach could lead to the definition of magneto-structural correlation essential for the rational design of complexes with targeted magnetic properties or for the identification of unknown reactive metallic species involved in catalysis. To illustrate this combined approach the high spin MnII, MnIII and MnIV ions have been taken as specific examples. The first part deals with the anal. of the EPR expts. as a function of the ions under investigation and the conditions of the measurements, specifically: (i) EPR spectra recorded under high vs. low frequency conditions with respect to magnetic anisotropy, (ii) EPR spectra of non-integer (Kramers) vs. integer (non-Kramers) spin states and (iii) mono- vs. multi-frequency EPR spectra. In the second part, two main quantum chem. approaches, which have proven their capability to predict magnetic anisotropy, are described. More importantly, these calcns. give access to the different contributions of zero field splitting, key information for the full understanding of magnetic anisotropy. The last part demonstrates that such a combined exptl. and theor. approach allows for the definition of magneto-structural correlations. [on SciFinder(R)]