CW EPR spectra of 1-Nd, 1-Ce and 1-Sm are observed at temperatures below ~30 K (Figures 4 and Supporting Information Figures ). Much sharper spectra are observed from powders (such that it is difficult to remove polycrystalline effects) than from frozen solutions (toluene/hexane 9:1 v/v), indicating some relaxation and strain of the structures in the latter medium. The spectra are dominated in each case by the rhombic or axial effective g-values arising from transitions within a thermally isolated ground Kramers doublet of the ground Russell-Saunders state, which can be treated as an effective spin-1/2. In this approximation, the frozen solution EPR spectrum for 1-Nd (Figure ) can be modeled with the spin Hamiltonian Eqn 1.