Crystal Field Stabilisation Energy
The net energy gained by a complex through the preferential occupation of lower-energy d orbitals.
Formula / equation
CFSE = (−0.4n_t2g + 0.6n_eg)Δ₀
Unit
kJ/mol
In depth
CFSE explains the double-humped pattern in lattice energies and hydration enthalpies across the first transition series, and why d³ and d⁶ low spin configurations are unusually stable. Its magnitude also correlates with the kinetic inertness of a complex.
Examples in the real world
Low spin d⁶ cobalt(III) has a CFSE of −2.4Δ₀, which is why its complexes are so slow to exchange ligands.