Berlin 2005 – scientific programme
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MA: Magnetismus
MA 14: Molekularer Magnetismus
MA 14.4: Talk
Saturday, March 5, 2005, 14:30–14:45, TU H1012
Modifying the molecular magnetism of ferric stars by intermolecular interaction — •H. Rupp1, A. Scheurer2, S. Sperner2, I. Bernt2, U. Reimann2, R.W. Saalfrank2, and P. Müller1 — 1Physikalisches Institut III, Universität Erlangen-Nürnberg, E. Rommel Str. 1, 91058 Erlangen — 2Institut für Organische Chemie, Universität Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen, Germany
In the ferric star Fe(III)(Fe(III)L2)3, the outer Fe ions are linked via two ligands L = H3CN(CH2CH2O)2) to the central one in a star-like topology. SQUID and EPR measurements revealed a strong antiferromagnetic intramolecular Heisenberg coupling J = – 40 K and zero field splitting parameter D = – 0.57 K resulting in a S = 10/2 ground state. Using 2DEG ballistic Hall probes, magnetization measurements have been performed on the two complexes FeFe3 * 4 CHCl3 and FeFe3 * 3 CH2Cl2 which differ only in the solvent used for the crystallization process. In both types of crystals, chains of stars are coupled via hydrogen bonds. The strength of this intermolecular coupling depends on the solvent used. FeFe3 * 4 CHCl3 shows step-like hysteresis at temperatures below 0.8 K but FeFe3 * 3 CH2Cl2 even up to 1.2 K. In addition, the two compounds differ significantly in the shape of their magnetization hysteresis. We discuss the observed features in terms of intermolecular interactions between the stars.