Modulating the structural topologies and magnetic relaxation behaviour of the Mn–Dy compounds by using different auxiliary organic ligands

A pentanuclear heterometallic complex [MnIII4DyIII(HL)4{(py)2CO2}2Cl2](OH) (1, H3L = 2-((2-hydroxybenzylidene)amino)propane-1,3-diol, (py)2C(OH)2 = the gem-diol form of 2,2′-dipyridyl ketone) and a one-dimensional (1D) chain [Mn2Dy(HL)2(hmp)2(CH3COO)2N3]n·H2O (2, Hhmp = 2-pyridinemethanol) were obtained by the assemblies of the H3L ligand and Dy(NO3)3·5H2O with MnCl2·4H2O and 2,2′-dipyridyl ketone or with manganese acetate and 2-pyridinemethanol under different alkaline solutions. In 1, four MnIII ions formed an irregular tetrahedron, in which four MnIII ions were linked with the central DyIII by eight O atoms from HL2− or from (py)2CO22− ligands. In 2, one DyIII and two MnIII formed a [Mn2Dy] unit, in which the metal ions were bridged by one N3− ion and by four O atoms of two HL2− and two hmp− ligands, and then these [Mn2Dy] units were further linked by the O atoms from HL2− ligands and formed a 1D zigzag chain. Magnetic studies indicated that both complexes exhibit slow relaxation behavior, with the effective energy barriers of 7.9 K and 9.6(0) K for 1 and 2, respectively, which might represent new members for the rarely polynuclear Mn–Dy single molecule magnets. The orientations of the easy magnetization axes of DyIII ions in 1 and 2 were estimated by the Magellan program, indicating that the easy axes of DyIII in 1 are nearly directed to C16 and C47 from (py)2CO22− ligands, while the axis in 2 is almost directed to O5 (from the acetate ligand).