Are Ligand-to-Metal Charge Transfer (LMCT) and Metal-to-Ligand Charge Transfer (MLCT) characterized as localized or delocalized?

Ligand-to-Metal Charge Transfer (LMCT) and Metal-to-Ligand Charge Transfer (MLCT) are characterized as delocalized rather than localized. In these processes, the electronic transitions involve the transfer of electrons between the metal center and the ligands.

In LMCT, an electron is promoted from a ligand orbital (often a non-bonding or anti-bonding orbital) to a metal d orbital, while in MLCT, the electron moves from a metal d orbital to a ligand π* orbital. Both transitions involve the mixing of electron density between distinctly different components of the coordination complex, indicating that the electrons are not confined to one localized position or atom.

This delocalization of charge reflects the nature of the interaction between the metal and ligands where the transitions occur across the entire coordination sphere, allowing for broader and more complex interactions that cannot be described merely as localized. Understanding these charge transfer mechanisms highlights the role of electronic structures in determining the properties of transition metal complexes, including their optical and redox behavior.

Thus, the characterization of LMCT and MLCT as localized is incorrect; their true nature is delocalized due to the significant overlap of molecular orbitals and the resulting electron transfer from one component