Solution and solid state structures and magnetism of a series of linear trinuclear compounds with a hexacoordinate Ln^III and two terminal Ni^II centers

Reported are the syntheses, structures and magnetic properties, also by NMR spectroscopy in solution, of a series of 13 linear trinuclear 3d-4f compounds with a lanthanide(iii) surrounded by two Ni^II ions, NiLn^III, where the central Ln^III is hexacoordinate. For three of the crystal structures, an additional H₂O molecule is coordinated to the central Ln^III ion, leading to a monocapped trigonal prismatic structure. However, NMR spectroscopy indicates that in solution, these complexes also have a hexacoordinate Ln^III center. The solution magnetic anisotropies, determined by NMR spectroscopy, indicate that the axial components of the anisotropies are relatively small and that the Dy^III derivative might therefore not exhibit single molecule magnetism. The axial anisotropies determined by NMR spectroscopy are in good agreement with the expectations based on the distorted trigonal prismatic ligand field.