Synthesis, Structures, and Magnetic Properties of Doubly Face-Sharing Heterotrinuclear NiII–LnIII–NiII (Ln = Eu, Gd, Tb, and Dy) Complexes

Abstract

Abstract Heterotrinuclear [(NiIIL)2LnIII(NO3)] complexes (where H3L = 1,1,1-tris[(salicylideneamino)methyl]ethane and Ln = Gd (1), Eu (2), Tb (3), and Dy (4)) were prepared by treating [Ni(H1.5L)]Cl0.5 with Ln(NO3)3·6H2O in the presence of triethylamine. Complexes 1·2CH3OH, 3·2CH3OH, and 4·C2H5OH·0.5H2O crystallized in the triclinic space group,Z=2, while 2·CH3OH·0.5H2O crystallized in the tetragonal space group, I41⁄a (No. 88), with Z=8. All the complexes had very similar structures. Each complex was a doubly face-sharing trinuclear molecule. The NiII ion is coordinated by the L3− ligand in an N3O3 coordination sphere, and the three phenolate oxygen atoms coordinate to an LnIII ion as bridging atoms. The LnIII ion is eight coordinate with six phenolate oxygen atoms of the two L3− ligands and two oxygen atoms of NO3−. Coordination of the NO3− group entails a bending of the Ni···Ln···Ni angle (ca. 140°). All the complexes involve π–π and CH–π interactions between the neighboring molecules to form a three-dimensional structure. Temperature-dependent magnetic susceptibility and field-dependent magnetization measurements on 1 showed a ferromagnetic interaction between the NiII and GdIII atoms. A ferromagnetic interaction was also suggested for NiII–TbIII (3) and NiII–DyIII (4).(No. 2), with