Which theory discusses the relationship between ligand bonding and degradation of d orbitals in metal complexes and the geometry of metal complexes and the splitting of d orbitals? 

The correct answer is Crystal field theory (CFT).

Key Points

• Crystal field theory (CFT)
  • ​Crystal field theory (CFT) discusses the relationship between ligand binding and degradation of d orbitals in metal complexes, the geometry of metal complexes, and the splitting of d orbitals.
  • The propensity of transition metals to form complexes is one of their key characteristics. A complex can be thought of as having several ligands encircling a core metal atom or ion.
  • Crystal field theory governs how these ligands interact with the central metal atom or ion.
  • The interaction between a metal ion and ligand is viewed by the 1929-founded crystal field theory as essentially an electrostatic phenomenon, with the ligands being considered as point charges close to the atomic orbitals of the central atom.
  • Using molecular orbital theory, crystal field theory was developed and expanded to consider the partially covalent nature of bonding between the ligand and metal atom.

Additional Information

• The metal-ligand bond was defined by crystal field theory as an ionic bond that solely results from electrostatic interactions between the metal ions and ligands.
• In the crystal field theory, anions are viewed as point charges, whereas neutral molecules are viewed as dipoles. Transition metals' d orbitals degenerate, or have the same energy, when they are not bound to any ligands.
• Due to the varied symmetries of the d orbitals and the inductive influence of the ligands on the electrons, the d orbitals split apart and become non-degenerate when they begin bonding with other ligands.