The electronic structures of the trans-[Cr I I I (cyclam)X 2 ] n + (cyclam=1,4,8,11-tetraazacyclotetradecane, X=Cl - , OH - , and H 2 O) were investigated. The spin quartet excited states of these complexes were assigned on the basis of a Gaussian analysis of UV-Vis absorption spectra. The spin Hamiltonian parameters of the ground states, especially the zero-field splittings, were determined from the randomly oriented frozen solution electron paramagnetic resonance spectra. The calculated zero-field splitting parameters determined from the second-order spin-orbit couplings with the nearest excited quartet states were found to deviate from those observed experimentally. The deviations were found to reflect the bond covalency of the axial ligators.