Valence Bond Theory of Complexes
The model describing coordinate bonding as the overlap of filled ligand orbitals with hybridised empty orbitals on the metal.
Formula / equation
d²sp³, sp³d², sp³, dsp²
Unit
Dimensionless
In depth
Inner orbital complexes use (n−1)d orbitals and are usually low spin, while outer orbital complexes use nd orbitals and are high spin. The model predicts geometry and magnetic behaviour but offers no explanation at all for the colours of complexes.
Examples in the real world
[Co(NH₃)₆]³⁺ as d²sp³ and diamagnetic; [CoF₆]³⁻ as sp³d² and paramagnetic.