Frontier Electron Density Pattern of Dioxin Congeners

Electron densities of highest occupied molecular orbitals (HOMO) of 75 congeners of chlorinated dibenzo-p-dioxins and a nonchlorinated dibenzo-p-dioxin were calculated. HOMO electron densities are localized mainly in out of plane (pi) orbitals of the 12 carbons and 2 oxygens. These HOMO densities were used as variables in a multivariate statistical analysis. By principal component analysis, the 76 dioxins were classified according to their character. The most toxic dioxins have large negative values of the third principal component scores.