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

Two carboxylate-bridged DyIII complexes, [Dy2(piv)5(μ3-OH)­(H2O)]n (1) and [Dy2(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 [Dy4(μ3-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 DyIII ions of the Dy4 unit in 1 and weak intramolecular antiferromagnetic interaction between DyIII ions and/or depopulation of the DyIII 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 ≈ 4.5 K, while 2 exhibits field-induced single-molecule-magnet behavior with ΔE/kB = 28.43 K under a 2 kOe external field.