The diagrams of MLCT and d-d excited states of the complexes [Ru(NH ₃)₅(py-X)]²⁺ are calculated using semiempirical CINDO/S method. Comparison of the relative energies of MLCT and d-d excited states leads to the understanding of the background of the rules, found earlier by Ford et al., that govern photochemical activity of the Ru(II) complexes under consideration.