Using DFT and ELF topological analysis, we study the directionality of the Pb2+ lone pair in the presence of neutral and anionic ligands. Archetypal [PbLn(HL)(m)](2 n) complexes (n = 1-3, m = 1-7, L = Cl or SH ) are investigated in the gas phase or using a solvation continuum. We show that the presence of only one anion within the coordination sphere of Pb2+ induces hemidirectionality for all complexes. Such a finding is important for future toxicology studies if one wants to stabilize Pb2+ valence shell in a hemidirected structure, a key issue in the search for specific chelators of lead. (C) 2011 Elsevier B. V. All rights reserved.