A series of one-dimensional Ni(2)Ln cationic complexes have been prepared by assembling the in situ generated dinuclear mesocate [Ni-2(mbplb)(3)](2-) building block [H(2)mbpb is the ligand 1,3-bis(pyridine-2-carboxamide)benzene] with Ln(3+) metal ions (Ln(3+) = Gd, Tb, Dy). The crystal-field potentials for the two types of site symmetries found for these 3d-3d-4f complexes (LnO(7) and LnO(8)) are quite different, which has a direct influence on the depopulation of the Stark sublevels, the magnetic anisotropy, and the magnetic properties.