Structural correlations between the crystal field and magnetic anisotropy of Ln-Cu single-molecule magnets

Mixed ligand Ln(2)Cu(2) tetranuclear complexes, [{LnCu(L4)(L5)(NO(3))(2)}(2)] (L4(-) is a Schiff base ligand derived from o-vanilate, L5(2-) is a nitromethyl derivative of L4(-); Ln=Gd(4), Tb(5), and Dy(6)), were synthesized by reacting the corresponding dinuclear complexes [LnCu(o-vanilate)(2)(NO(3))(3)] with ethylamine in a nitromethane solution. From detailed studies of magnetic anisotropies 5 was shown to behave as an SMM, whereas 6 was not an SMM.