The reaction of LH3 with Ni(ClO4)(2) center dot 6H(2)O and lanthanide salts in a 2:21 ratio in the presence of triethylamine leads to the formation of the trinuclear complexes [L(2)Ni(2)Ln][ClO4] (Ln = La (2), Ce (3), Pr (4), Nd (5), Sm (6), Eu (7), Gd (8), Tb (9), Dy (10), Ho (11) and Er (12) and L (S)P[N(Me)N=CH-C6H3-2-O-3-OMe](3)). The cationic portion of these complexes consists of three metal ions that are arranged in a linear manner. The two terminal nickel(II) ions are coordinated by imino and phenolate oxygen atoms (3N, 3O), whereas the central lanthanide ion is bound to the phenolate and methoxy oxygen atoms (12O). The Ni-Ni separations in these complexes range from 6.84 to 6.48 angstrom. The Ni-Ni, Ni-Ln and Ln-O-phenolate bond distances in 2-12 show a gradual reduction proceeding from 2 to 12 in accordance with lanthanide contraction. Whereas all of the compounds (2-12) are paramagnetic systems, 8 displays a remarkable S-T = 11/2 ground state induced by an intramolecular Ni . . .Gd ferromagnetic interaction, and 10 is a new mixed metal 3d/4f single-molecule magnet generated by the high-spin ground state of the complex and the magnetic anisotropy brought by the dysprosium(III) metal ion.