Slow Magnetic Relaxation in Two New 1D/0D DyIII Complexes with a Sterically Hindered Carboxylate Ligand

Two carboxylate-bridged Dy-III complexes, [Dy-2(piv)(5)(mu(3)-OH)(H2O)](n) (1) and [Dy-2(piv)(6)(phen)(2)] (2) (pivH = pivalic acid; phen = 1,10-phenanthroline), have been synthesized and structurally characterized. Complex 1 takes a one-dimensional (1D) chain structure based on [Dy-4(mu(3)-OH)(2)(piv)(8)(H2O)(2)](2+) units, while complex 2 is a dinuclear structure bridged by syn,syn-carboxylates. Magnetic investigation indicates weak ferromagnetic interaction between adjacent Dy-III ions of the Dy-4 unit in 1 and weak intramolecular antiferromagnetic interaction between Dy-III ions and/or depopulation of the Dy-III excited-state Stark sublevels in 2. Alternating-current susceptibility measurements revealed frequency- and temperature-dependent out-of-phase signals under a zero direct-current field in 1, with typical slow magnetic relaxation behavior with an anisotropic barrier U approximate to 4.5 K, while 2 exhibits field-induced single-molecule-magnet behavior with Delta E/k(B) = 28.43 K under a 2 kOe external field.