Verifying the PCP-rule by five-center bond indices

摘要

According to the recently discovered PCP-rule, the (stabilizing) energy-effect of the cyclic conjugation in the 5-membered ring of acenaphthylene-and fluoranthene-type polycyclic conjugated hydrocarbons increases with the number of phenyl-cyclopentadienyl (PCP) fragments present in the molecule. It is now shown that the validity of the PCP-rule is also supported by the 5-cen-ter bond indices, an independent quantitative theoretical measure of cyclic conjugation in 5-membered rings.