Ligand field theory

   Although we shall not be concerned with the mathematics of ligand field theory, it is important to comment upon it briefly since we shall be using ligand field stabilization energies (LFSEs) later in this chapter. Ligand field theory is an extension of crystal field theory which is freely parameterized rather than taking a localized field arising from point charge ligands. Ligand field, like crystal field, theory is confined to the role of d orbitals, but unlike the crystal field model, the ligand field approach is not a purely electrostatic model. It is a freely parameterized model, and uses Δ_oct and Racah parameters (to which we return later) which are obtained from electronic spectroscopic (i.e. experimental) data. Most importantly, although (as we showed in the last section) it is possible to approach the bonding in d-block metal complexes by using molecular orbital theory, it is incorrect to state that ligand field theory is simply the application of MO theory.