Condensed two- and three-dimensional aromatic systems: a theoretical study on the relative stabilities of isomers of CB₁₉H₁₆⁺, B₂₀H₁₅Cl, and B₂₀H₁₄Cl₂ and comparison to B₁₂H₁₀Cl₂^2-, C₆H₄Cl₂, C₁₀H₇Cl, and C₁₀H₆Cl₂

Abstract

DFT studies (B3LYP/6-31G^∗) on mono- and dichloro derivatives of benzene, naphthalene, B₁₂H₁₂^2-, four-atom-sharing condensed systems B₂₀H₁₆, and monocarborane isomers of B₂₀H₁₆ are used to compare the variation of relative stability and aromaticity between condensed aromatics. The trends in the variation of the relative energies and aromaticity in these two- and three-dimensional systems are similar. Aromaticity, estimated by NICS values, does not change considerably with condensation or substitution. The minor variation in the relative energies of the isomers of chloro derivatives is explained by the topological charge stabilization rule of Gimarc. The compatibility of the cap and ring orbitals decides the relative stability of CB₁₉H₁₆⁺.