Single-Molecule Magnet of a Tetranuclear Dysprosium Complex Disturbed by a Salen-Type Ligand and Chloride Counterions

A series of three salen-type lanthanide complexes, e.g., [Dy4(L)2(HL)2Cl2(μ3-OH)2]2Cl2(OH)2·3CH3CH2OH·H2O (1) and [Ln4(L)2(HL)2Cl2(μ3-OH)2]­Cl2·5CH3OH·4CH2Cl2 (Ln = TbIII, 2; HoIII, 3) have been isolated by the reactions of H2L (H2L = N,N′-bis­(3-methoxysalicylidene)­cyclohexane-1,2-diamine) with LnCl3·6H2O. X-ray crystallographic analysis reveals that all complexes 1–3 are isostructural, in which four Ln ions and eight O atoms form the distorted defective dicubane {Dy4O8} cores. Magnetic studies indicate that complex 1 exhibits two slow magnetic relaxation processes with effective energy barrier Ueff = 55.71 K under a zero direct-current field, which is attributed to the two coordination geometries of the DyIII ions with a salen-type ligand and coordination of a chloride counterion. It represents the highest energy barrier among the salen-type tetranuclear lanthanide single-molecule magnets.