Complexes of formulas [Ln(e-cl)8] (F3C-SO3)3 (Ln = La-Eu) and [Ln(ε‐cl)7] (F3C-SO3)3 (Ln = Gd, Tb, Dy, Yb, Lu, ε‐cl = ε‐caprolactam) were synthesized and characterized by elemental analysis, infrared spectroscopy, visible absorption spectroscopy of the Nd compound and emission spectroscopy of the Eu compound and the Gd compound, doped with Eu. IR experimental data suggest that the e-caprolactams are bonded to the central ions through the carbonyl oxygen and that the anions are not coordinated. The parameters calculated from the visible absorption spectrum of the Nd compound suggest electrostatic metal-ligand bonds. The emission spectrum of the europium compound suggests a D2d distorted towards C2v symmetry. X-ray single crystal analysis of the Pr compound shows that the anions are not coordinated and that the coordination polyhedron around the Pr3+ion has a slightly distorted D2d (dodecahedral) symmetry.