Mechanisms for the incorporation of a nitrogen atom into polycyclic aromatic hydrocarbon cations

The growth of a second aromatic ring, for cationic species containing a nitrogen atom, is studied at the B3LYP/6-31G∗ level of theory. For the most favorable processes, the maximum barrier is about 15 kcal/mol and is associated with the breaking of an aromatic C–H bond. This barrier is similar in magnitude to that found for the pure hydrocarbon case. Thus, the inclusion of nitrogen into polycyclic aromatic hydrocarbon (PAH) rings seems favorable if HCN is present during the ring growth processes.