Charge competition in halogenated hydrocarbons



The distribution of electronic charge in a molecule plays a major role in determining the molecule's physical, chemical, and biological properties. For studies of charge distributions, halogenated hydrocarbons are especially informative prototype systems, because the overall charge distributions depend strongly on both the identities and relative positions of the halogen substituents. In this report, we examine how the placement and identities of the halogen substituents affect the natural population analysis, atoms in molecules, and Gasteiger partial atomic charge distributions in representative saturated (methanes and ethanes), unsaturated (ethylenes), and aromatic (benzenes) halogenated hydrocarbons, using density functional calculations. The results are interpreted in terms of the electronegativities and the charge capacities of the halogens. The relationships of these charge distributions to the electrostatic potential maps of the compounds are also explored. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012