Crystal Field Theory

Crystal field theory is a model in chemistry describing how the electron orbitals of a transition metal ion are split into different energy levels by the electrostatic field of surrounding ions or molecules, called ligands, in a coordination complex. Developed originally by physicist Hans Bethe in 1929 for describing crystalline solids, the theory was later applied to coordination chemistry by John Hasbrouck Van Vleck in the 1930s to explain the distinctive colors and magnetic properties of transition metal compounds. The theory remains a standard tool for predicting and explaining the optical absorption spectra, magnetism and stability of coordination compounds, though it has been substantially extended by the more complete ligand field theory.