  We discuss the quantum chemical nature of the Lead(II) valence basins,
sometime called the Lead "lone pair". Using various chemical interpretation
tools such as the molecular orbital analysis, Natural Bond Orbitals (NBO),
Natural Population Analysis (NPA) and Electron Localization Function (ELF)
topological analysis, we study a variety of Lead(II) complexes. A careful
analysis of the results show that the optimal structures of the lead complexes
are only govern by the 6s and 6p subshells whereas no involvement of the 5d
orbitals is found. Similarly, we do not find any significant contribution of
the 6d. Therefore, the Pb(II) complexation with its ligand can be explained
through the interaction of the 6s2 electrons and the accepting 6p orbitals. We
detail the potential structural and dynamical consequences of such electronic
structure organization of the Pb (II) valence domain.
