Influence of crystal-field perturbations on the room-temperature magnetic anisotropy of lanthanide complexes

The room-temperature magnetic susceptibility anisotropy of eight-coordinate lanthanide ions was modelled numerically for polyhedra resulting from dist ortions of the regular cube to a tetragonal prism, antiprism, and dodecahed ron. Our aim is to illustrate how the magnitude and sign of the room-temper ature magnetic anisotropy can be related to the shape of the coordination p olyhedron and to estimate its maximum value. Tb(III), Dy(III), and Tm(III) ions are found to have the largest values of the magnetic anisotropy in all coordination polyhedra. These results are helpful to rationalize the orien tational behavior of lanthanide-containing liquid crystals in an external m agnetic field. (C) 2001 Elsevier Science B.V. All rights reserved.