Berlin 2018 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 33: Biomedical and molecular magnetism
MA 33.6: Vortrag
Mittwoch, 14. März 2018, 16:15–16:30, H 1012
Electronic Configuration and Charge Transfer in Organometallic Ligand Complexes of Terbium (I, II, III) Ions — •Martin Timm1, Christine Bülow1, Vicente Zamudio-Bayer2, Rebecka Lindblad3, Bernd von Issendorff2 und Tobias Lau1 — 1Helmholtz-Zentrum Berlin für Materialien und Energie, 12489 Berlin, Germany — 2Albert-Ludwigs-Universität Freiburg, 79098 Freiburg, Germany — 3Synkrotronljusfysik, Lunds Universitet, 22100 Lund, Sweden
Complexes of carbocyclic polyene ligands with lanthanoid atoms are of interest because of their large magnetic moments and magnetic anisotropy energy. In many of these complexes, there is a competition between charge transfer to the ligand in order to reach closed electronic shells according to Hückel’s (4n + 2) rule, and the preference of lanthanoids to form +III oxidation states. We have, therefore, studied cationic mono- and di-ligated complexes of terbium atoms and cyclic CnHn (n = 5, 6, 8) molecules with preferential 0, -1, and -2 charge states by means of X-ray absorption and X-ray magnetic circular dichroism spectroscopy at the terbium M4,5 edge. In all cases, we find the 4f8 configuration of terbium in its +III oxidation state. Furthermore, x-ray absorption spectra at the carbon K edge of the ligands indicate deviations from their planar ring structures, which is evidence of non-aromaticity.