The Versatility of Ethylene Glycol to Tune the Dimensionality and Magnetic Properties in DyIII-Anilato-Based Single-Ion Magnets.

Abstract

We exploit the high versatility of the solvent ethylene glycol (eg = CH2OH-CH2OH) acting as a ligand with three different coordination modes: terminal (κO), chelate (κ2O,O'), and bridge (1κO,2κO') to prepare a novel family of six different coordination polymers with DyIII and three different anilato ligands (3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone dianion = C6O4X22-, with X = H, Cl, and Br). With the X = H derivative (dhbq2-), we have prepared [Dy2(dhbq)3(eg)2(μ-eg)]·4eg·2H2O (1), a 3D diamond-like network with a chelate and bridging eg molecules. With the X = Cl derivative (chloranilato), we have prepared [Dy2(C6O4Cl2)3(eg)4]·2eg·H2O (2) and [Dy2(C6O4Cl2)3(μ-eg)(H2O)4]·2eg·7H2O (3). Compound 2 has a 2D (6,3)-gon brick-wall lattice and contains a chelate and a terminal eg molecule. Compound 3 has a 3D diamond-like topology as 1, although now the chelate eg has been replaced by two water molecules. Finally, with the X = Br derivative (bromanilato), we have obtained [Dy2(C6O4Br2)3(eg)2(CH3OH)2]·2eg·4CH3OH (4), [Dy2(C6O4Br2)3(eg)4]·4eg (5), and [Dy2(C6O4Br2)3(eg)3(H2O)]·2eg·H2O (6). Compound 4 has a 2D (6,3)-gon herringbone topology and contains a chelate eg and a MeOH molecule. Compounds 5 and 6 have a 2D (6,3)-gon brick-wall topology with a chelate and a terminal eg molecules (in 5 and in one of the two independent Dy centers of 6). The other Dy center in 6 has a chelate eg and a water molecule. All the compounds show slow relaxation of the magnetization at low temperatures (in compounds 1, 2, and 5 with no applied DC field). The magnetization of compounds 1-6 relaxes through Orbach and direct mechanisms when a DC field is applied and through an Orbach and/or quantum tunneling mechanism when no DC field is applied.