Modulating the Magnetic Interaction in New Triple-Decker Dysprosium(III) Single-Molecule Magnets.

A new type of dinuclear dysprosium(III) complex based on phthalocyanine and salicylaldehyde derivatives (HL-R), [Dy2(Pc)2(L-R)2(H2O)]·2THF (R = OCH3 (1), OC2H5 (2); H2Pc = phthalocyanine; HL-OCH3 = 2-hydroxy-3-methoxybenzaldehyde; HL-OC2H5 = 3-ethoxy-2-hydroxybenzaldehyde), was successfully synthesized and structurally characterized. Complex 1 features a sandwich-type triple-decker structure, where two coplanar L-OCH3 ligands lie in the middle layer shared by two eight-coordinated DyIII ions and two Pc ligands are located in the outer layer. In 2, the introduction of an ethoxy group generates a noncoordination mode for the Oalkoxy atom. Magnetic studies indicate that complex 1 behaves as a zero-field single-molecule magnet with a higher energy barrier, while 2 exhibits a fast tunneling relaxation process. Theoretical calculations revealed that changes in the ligand field environment around DyIII ions can significantly affect the arrangement of the main magnetic axes and further result in distinct magnetic interactions as well as different relaxation behaviors.