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Tetranuclear [Cu-Ln]2 single molecule magnets: synthesis, structural and magnetic studies
Jean-Pierre Costes1, Sergiu Shova, Wolfgang Wernsdorfer
1Laboratoire de Chimie de Coordination du CNRS, UPR 8241, liée par conventions à l'Université Paul Sabatier et àl'Institut National Polytechnique de Toulouse, 205 route de Narbonne, 31077, Toulouse, Cedex, France. costes@lcc-toulouse.fr
Abstract:
A trianionic ligand H3L (2-hydroxy-N-(2-[[(2-hydroxyphenyl)methylene]amino]-2-methylpropyl)benzamide) with an inner N2O2 coordination site and an oxygen atom coming from an amide function not involved in this site yields monoanionic LCu- complexes that react with Ln(hfa)3 x 2H2O (hfa = hexafluoroacetylacetonato ligand) to give dinuclear Cu-Ln complexes that self-assemble into tetranuclear species, as demonstrated by the structural determination of the [LCuDy(hfa)2(dmf)2]2 complex. High-spin species are then isolated for two ferromagnetic interactions are active in the [Cu-Gd]2 entities, through the double phenoxo bridge (J = 3.2 cm(-1)) and through the single amide bridge (j = 0.54 cm(-1)). These interactions are still present in the [Cu-Tb]2 and [Cu-Dy]2 complexes which behave as single molecule magnets (SMMs), due to the introduction of anisotropic Ln ions in place of Gd ions.
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