[en] Heterotrinuclear [(Ni^IIL)₂Ln^III(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(H_1.5L)]Cl_0.5 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, P1-bar (No.2), with 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 Ni^II ion is coordinated by the L^3- ligand in an N₃O₃ coordination sphere, and the three phenolate oxygen atoms coordinate to an Ln^III ion as bridging atoms. The Ln^III ion is eight coordinate with six phenolate oxygen atoms of the two L^3- ligands and two oxygen atoms of NO₃^-. Coordination of the NO₃^- group entails a bending of the Ni...Ln...Ni angle (ca. 140deg). 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 Ni^II and Gd^III atoms. A ferromagnetic interaction was also suggested for Ni^II-Tb^III (3) and Ni^III-Dy^III (4). (author)