For axial Dy 3+ complexes, the exclusion of equatorially coordinating ligands is inherently challenging due to the relatively large size of the highly Lewis acidic Dy 3+ ions, the lack of directionality in Ln bonding regimes, and the tendency to maximize contacts with hard ligand donor atoms. The difficulties encountered in the isolation of axial dysprosocenium cations bending of the Dy-X-Cipso angle is observed with halogen size; this can be attributed to the anisotropic electrostatic potential distribution around the halide atoms. The variance in angle is greatest between PhF and PhCl, which is likely due to the much longer Dy-X distances Ueff is higher than previously reported for [Dy(Cp*)2] + (ca. 1000-1100 cm -1 ), which can be attributed to different geometries used and methods of determining Ucalc. In contrast, samples Halobenzene coordination promotes all relaxation mechanisms, although the observed rates also depend on induced structural distortions to the {Dy(Cp*)2} + core. These data confirm that for the [Dy(Cp*)2] + cation to be isolated and free of equatorial ligand interactions, a more weakly coordinating counter-anion needs to be employed or a significantly different experimental approach needs to be followed, e.g. encapsulation of [Dy(Cp*)2] + in an appropriate host-guest matrix.