New binuclear model compounds for the study of the 4f–4f exchange interaction

Two new homobinuclear 4f–4f complexes, [LnIII(L)3]2, (Ln=Pr 1; Gd 2) have been synthesized (L−=2,6-diformyl-4-methylphenolato). The crystallographic investigation of 1 reveals centrosymmetric binuclear entities with the metallic centers connected by two of the anionic ligands. The praseodymium ions are bridged by the phenoxo oxygen atoms. One carbonyl group of a bridging molecule is coordinated to one Pr(III) ion, while the other one is coordinated to the second Pr(III) ion. The other four L− ions act as terminal chelated ligands, through the phenoxo oxygen atom and one carbonyl group. The distance between the Pr(III) ions within the binuclear entity is 4.0711(4) Å. The supramolecular solid-state architecture is sustained by a system of π–π interactions. The cryomagnetic study of 2 reveals a very weak antiferromagnetic interaction between the Gd(III) ions (J=−0.053 cm−1, ).