Slow magnetic relaxation in a Dy 3 triangle and a bistriangular Dy 6 cluster.

Two lanthanide single-molecule magnets (SMMs) [Dy 3 (μ 3 -OH)(HL-1) 3 (H 2 O) 3 ](NO 3 ) 2 ·3H 3 O (1, H 3 L-1 = ( E )-3-(((8-hydroxyquinolin-2-yl)methylene)amino)propane-1,2-diol) and [Dy 6 (μ 3 -OH) 4 (H 2 L-2) 4 (HL-2) 2 (L-2) 2 ] (2, H 3 L-2 = ( E )-2-hydroxy- N '-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) were synthesized and characterized structurally and magnetically. Complex 1 contains a triangular Dy 3 core in which the three Dy 3+ ions share a μ 3 -OH - anion and the deprotonated ligands of (HL-1) 2- serve both capping and bridging functions, while 2 displays a centrosymmetric hexanuclear Dy III structure with two similar Dy 3 triangular cores ligated by two fully deprotonated (L-2) 3- ligands, each of which shares two μ 3 -OH - anions. All the Dy III ions are eight-coordinated with quasi D 2d or C 2v symmetry. Magnetic studies reveal that 1 exhibited two-step magnetic relaxation under an applied dc field of 800 Oe, with effective energy barriers of 40.1 and 31.0 K for the slow relaxation (SR) and fast relaxation regimes (FR), respectively. Meanwhile, 2 only showed a tail of slow magnetic relaxation at above 2 K. Ab initio calculations have been carried out to show the nature of their different magnetic properties.