Spin polarization of the atomic valence shell in metal complexes

This chapter reviews the concept of the atomic valence shell and its polarization from the Quantum Chemical Topology point of view. First, we present a brief description of the Laplacian of electron density and atomic graph, which is a topological object that summarizes the location and properties of the valence shell. We also explore the concepts of spin density and spin valence shells and their evolution during different processes of chemical interest related to metal complexes. Finally, we explore the energetic changes in the valence region. Our approach states that the ligands provoke a redistribution of the electron density to maximize the nuclear-electron interactions in each spin valence shell to overpass the concentration of electron-electron interactions, resulting in a polarization pattern that determines the position of the ligands.