TOPOGRAPHICAL ANALYSIS OF ELECTRON-DENSITY AND MOLECULAR ELECTROSTATIC POTENTIAL FOR CYCLOPROPABENZENES AND CYCLOBUTABENZENES

The electron density (ED)- and molecular electrostatic potential (MESP)-based topographical studies are carried out for investigating the bonding and charge localization features, respectively, of cyclopropa- and cyclobutabenzenes. The ED topography brings out an increase in the double-bond character of the annulated bond. This analysis also shows that it is not possible to assign alternate single and double bonds for benzene in these compounds, as is conventionally done. The ellipticity data are used for obtaining information regarding the pi character of the bonds and anisotropy of charge distribution. The results of MESP topography indicate that the four- and three-membered rings have a ''push'' and ''pull'' effect, respectively, on the aromatic nucleus. The ring-opening type of reactions in systems containing cyclopropane and the electrophilic attack at the beta position for annulated benzenes are also explained by the MESP analysis.