Assembling ferromagnetically coupled (Cu, Gd) pairs: toward higher spin entities

We have previously shown that in strictly dinuclear copper-gadolinium complexes. ferromagnetism is an intrinsic property of the Cu-Gd pair. yielding a S= 4 ground stare. We want non to show that similar dinuclear complexes obtained with an original ligand having a supplementary oxygen donor atom are able to;assemble in order to yield higher spin entities with :a S = 8 ground state. These dimeric entities have four metallic centres. two Cu(II) :Ind two Gd(III) ions. arranged at the vertices of a rectangle in such a way that two different ferromagnetic Cu-Gd interactions are operative. The stronger one (7 cm(-1)) is supported by a double phenolate bridge (CuO2Gd) and the weaker one (0.6 cm(-4)) by a single amido bridge (Cu-N-C-O-Gd). (C) 2001 Academie des sciences Editions scientifiques et medicales Elsevier SAS.