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10.1002/ejic.201901150
European Journal of Inorganic Chemistry
their phenoxo functions. Note that the presence of auxiliary ligands with a good chelating
ability for the Gd ion, as the diketonato ligands, allows isolation of tetranuclear species only,
whatever the number of amide functions.
Introduction
We have previously shown that trianionic compartmental ligands with two
coordination sites, an inner N2O2 and an outer O2O2 site able to coordinate the 3d and the 4f
ions respectively, along with one oxygen atom of an amide function not involved in these
coordination sites, yield dinuclear CuLn entities that self-assemble in tetranuclear Cu2Ln2
complexes, as a consequence of a head to tail assembling of two dinuclear species. In the case
of Cu2Gd2 entities, the complexes possess a S = 8 spin ground state due to the presence of two
active ferromagnetic interactions, one through the double phenoxo bridge and the second one
through the amide bridge.1 In order to change the spin state of these 3d-4f entities, we2 and
other research teams3,4 have tried to modify the ligands and also to introduce different counter
ions around the 4f ions. The use of different ligands with outer O2O2 or O2O sites does not
improve the nuclearity of the samples, as shown in the structurally characterized complexes
already published.1-4 In these later complexes, the 4f ions are surrounded by eight or nine
oxygen atoms. A way to change the nuclearity would consist in increasing the number of
oxygen atoms interacting magnetically with the copper ions in the coordination sphere of the
4f ion. There are two ways to do it: first, using dianionic or trianionic ligands possessing one
amide function and an outer coordination site reduced to one phenoxo oxygen atoms directly
connected to the copper ion and second, using tetraanionic ligands with two amide functions.
The later solution has the advantage to increase the attraction of the 4f ion for the negatively
charged dianionic 3d complex and to decrease the number of auxiliary anionic species around
the 4f ion. In the former solution, it is expected that the Ln ion could link two copper
complexes in order to yield trinuclear Cu-Ln-Cu entities instead of the dinuclear Cu-Ln ones,
which, by self-assembling through the amidato functions, should be able to yield, at least,
hexanuclear complexes. In this paper the two solutions will be examined, along with the role
held by the auxiliary ligands needed for reaching the electroneutrality of the isolated entities.
Results and discussion
Syntheses.
It has previously shown5-7 that compartmental Schiff base ligands having two
coordination sites sharing two oxygen atoms coming from two phenol functions were able to
yield strictly heterodinuclear 3d-4f complexes. In a following step we have described new
2
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Costes, Jean-Pierre
