Alternative Explanation of Metal Orbital Energy Orders in Coordination Compounds with Strong Ligand-Ligand Interactions

The relative order of d orbital energies in symmetrical molecules is determined in the case of highly interacting ligand‐ligand orbitals. For most symmetries this sequence turns out to be the same as obtained from crystal‐field or molecular‐orbital theory. The method starts from the order of ligand orbitals gained by topological considerations. The central metal‐ligand interaction is then treated by a perturbation in which the variation of $E_d{\mathrm{\hspace{0.17em}-\hspace{0.17em}E}}_x$ (energies for metal d and ligand x orbitals) is considered as the predominant factor.