The copper (ll) complexes with epa, tpa, epma, and tpma, potentially quadridentate L prolinamide derivatives (see text), have been characterised by visible absorption, circular dichroism (CD), IR, and ESR spectroscopies. The stabilities have also been determined by potentiometric titrations. All of the spectral features of the complex with dianionic tpaH₂ indicated an ordinary planar geometry, while those of the tpmaH₂ complex suggested an unusual ligand field containing a strong apical coordination. The complexes of dianionic epaH_-2 and epmaH_-2 were thought to take a distorted geometry on the basis of the full splitting of d-d transitions and the rhombic ESR. The spectroscopic properties electronic states, and stabilities have been discussed in terms of the ligand structures and the complex geometries.