Final answer:
In a MLCT complex, the proximity of the ligand and metal orbitals is determined by crystal field theory, which explains the interaction between metal and ligand orbitals. Strong-field ligands produce large splitting and favor low-spin complexes, while weak-field ligands favor high-spin complexes.
Step-by-step explanation:
Crystal field theory explains the interaction between metal and ligand orbitals in a MLCT (Metal-to-Ligand Charge Transfer) complex. According to crystal field theory, ligands near the metal ion affect the energies of the metal's d orbitals. The arrangement of ligands can cause the d orbitals to split into sets with different energies. The proximity of the ligand and metal orbitals determines the magnitude of the crystal field splitting energy (Aoct). Strong field ligands produce a large splitting, favoring low-spin complexes, while weak field ligands produce a small splitting, favoring high-spin complexes.