Asymmetry-unit-dominated double slow-relaxation modes of 2,6-dimethyl-3,5-heptanedione dysprosium SMMs†
Abstract
A series of Hdmh mononuclear dysprosium complexes, namely [Dy(dmh)3(MeOH)] (1), [Dy(dmh)3(2,2′-bpy)]2 (2), and [Dy(dmh)3(phen)] (3), and analogue complexes of complex 2 [Lu(dmh)3(2,2′-bpy)]2 (4) (Hdmh = 2,6-dimethyl-3,5-heptanedione, 2,2′-bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline), have been isolated by reaction of Hdmh and LnCl3·6H2O with 2,2′-bpy/phen auxiliary ligands. X-ray crystallographic analysis reveals that all complexes 1–4 are mononuclear complexes. Complex 1 is seven-coordinated by three dmh ligands and one methanol. Complexes 2, 3 and 4 are all eight-coordinated by three dmh ligands and one 2,2′-bpy or phen. Magnetic studies indicate that complexes 2 and 3 exhibit slow relaxation at zero field but complex 1 does not. Strikingly, complex 2 exhibits mainly single slow relaxation under zero dc field and double slow relaxation under optimized dc field. In contrast, complex 3 exhibits double slow relaxation under zero dc field and single slow relaxation under optimized dc field. The origins of the double slow relaxation modes of complex 2 have been verified by dilution sample of complex 4.