Anilato-Based Coordination Polymers with Slow Relaxation of the Magnetization: Role of the Synthetic Method and Anilato Ligand.

We have prepared and characterized three coordination polymers formulated as [Dy 2 (C 6 O 4 Cl 2 ) 3 (fma) 6 ] ⋅ 4.5fma (1) and [Dy 2 (C 6 O 4 X 2 ) 3 (fma) 6 ] ⋅ 4fma ⋅ 2H 2 O with X=Br (2) and Cl (3), where fma=formamide and C 6 O 4 X 2 2- =3,6-disubstituted-2,5-dihydroxy-1,4-benzoquinone dianion with X=Cl (chloranilato) and Br (bromanilato). Compounds 1 and 3 are solvates obtained with slow and fast precipitation methods, respectively. Compounds 2 and 3 are isostructural and only differ in the X group of the anilato ligand. The three compounds present (6,3)-gon two-dimensional hexagonal honey-comb structures. Magnetic measurements indicate that the three compounds show slow relaxation of the magnetization at low temperatures when a continuous magnetic field is applied, although with different relaxation times and energy barriers depending on X and the crystallisation molecules. Compounds 1-3 represent the first examples of anilato-based lattices with formamide and field-induced slow relaxation of the magnetization.