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Element specific determination of the magnetic properties of two macrocyclic tetranuclear 3d-4f complexes with a Cu3Tb core by means of X-ray magnetic circular dichroism (XMCD)

DOI: 10.1039/C7CP08689J DOI Help

Authors: K. Balinski (Universität Osnabrück) , L. Schneider (Universität Osnabrück) , Julia Wöllermann (Universität Osnabrück) , Anna Buling (Universität Osnabrück) , Loïc Joly (Université de Strasbourg) , C. Piamonteze (Paul Scherrer Institut) , H. L. C. Feltham (University of Otago) , S. Brooker (University of Otago) , A. K. Powell (Karlsruhe Institute of Technology) , B. Delley (Paul Scherrer Institute) , K. Kuepper (Universität Osnabrück)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics

State: Published (Approved)
Published: May 2018
Diamond Proposal Number(s): 11190

Abstract: We apply X-ray magnetic circular dichroism to address the internal magnetic structure of two very promising star shaped macrocyclic complexes with a CuII3TbIII core. These complexes are rare examples prepared with a macrocyclic ligand which show indications of SMM (Single Molecule Magnet) behavior, and they differ only in ring size: one is of a propylene linked macrocycle, [CuII3TbIII(LPr)(NO3)2(MeOH)(H2O)2](NO3)·3H2O (nickname Cu3Tb(LPr)), and the other is the butylene linked analogue, [CuII3TbIII(LBu)(NO3)2(MeOH)(H2O)](NO3)·3H2O (nickname Cu3Tb(LBu)). We analyze the orbital and spin contributions to the Cu and Tb ions quantitatively by applying the spin and orbital sum rules concerning the L2 (M4) / L3 (M5) edges. In combination with appropriate ligand field simulations we demonstrate that the Tb(III) ions contribute with high orbital magnetic moments to the magnetic anisotropy, whereas the ligand field determines the easy axis of magnetization. Furthermore, we confirm that the Cu(II) ions in both molecules are in a divalent valence state, the magnetic moments of the three Cu ions appear to be canted due to 3d-3d intramolecular magnetic interactions. For Cu3Tb(LPr), corresponding element specific magnetization loops, reflect that the Cu(II) contribution to the overall magnetic picture becomes more important as the temperature is lowered. This implies a low value for the 3d-4f coupling.

Journal Keywords: single molecule magnet; 3d-4f macrocycles, XMCD; sum rules, electronic and magnetic structure

Subject Areas: Physics, Chemistry

Instruments: I10-Beamline for Advanced Dichroism

Other Facilities: Swiss Light Source

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