Seven-Coordinate Lanthanide Sandwich-Type Complexes with a Tetrathiafulvalene-Fused Schiff Base Ligand

Three seven-coordinate lanthanide(III) sandwich-type mononuclear complexes with π-conjugated TTF-Schiff base ligand H2L (L(2-) = 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)(-) = [(η(5)-C5H5)Co(P(═O)(OEt)2)3](-)), [(L(OEt))Ln(L)]·0.25H2O (Ln(3+) = Dy(3+), 1; Tb(3+), 2; Ho(3+), 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.