A model potential is included in the diagonal elements of the Hamiltonian matrix used in IEH calculations on transition-metal complexes. The valence orbital ionization potentials are represented as polynomials of the valence electron population and the atomic number instead of, as is usual, polynomials of the atomic charge. The resulting matrix elements are used in calculations on a number of octahedral transition-metal complexes, and the results are compared for one complex with results obtained from other EH schemes.