Three seven-coordinate lanthanide(III) sandwich-type mononuclear complexes with pi-conjugated TTF-Schiff base ligand H2L (L2- = 2,2'-((2-(4,5-bis(methylthio)-1,3-dithiol-2-ylidene)-1,3-benzodithiole-5,6-diyl)bis(nitrilomethylidyne)bis(4-chlorophenolate)) and the tripodal ligand L-OEt(-) (L-OEt(-) = [eta(5)-C5H5)Co(P(=O)(OEt)(2))(3)](-)), [(L-OEt)Ln(L)]center dot 0.25H(2)O (Ln(3+) = Dy3+, 1; Tb3+, 2; Ho3+, 3), have been synthesized and structurally characterized. All of the complexes are also characterized by absorption spectra and electrochemical, spectroelectrochemical, and magnetic studies. The Dy complex exhibits the field-induced slow relaxation of magnetization with an energy barrier of 41.6 K, indicating it shows single lanthanide-based SMM behavior. Introduction of the redox-active TTF unit into the sandwich-type lanthanide(III) complexes with interesting magnetic properties renders them promising for elaboration of new hybrid inorganic-organic materials.