In this book, we have emphasized on the π-π stacking and halogen interaction among chlorobenzene in comparison to the interactions in chloro substituted ethene systems. Among the different stacked chlorobenzene systems, it has been observed that π-π stacking interaction energy of the staggered conformation (dihedral angle 120˚) gives more stable stacked model than that of others. We have also studied the variation of π-π stacking interaction in chloro substituted ethene systems (monochloroethene, dichloroethene, trichloroethene and tetrachloroethene) to compare the change in interaction energy values. Among all the chloro substituted ethene systems, stacked tetrachloroethene monomer results in the most negative interaction energy value and hence it gives more stable conformation.
