Density Functional Theory Study of the Formation of Naphthalene and Phenanthrene from Reactions of Phenyl with Vinyl- and Phenylacetylene

Reaction pathways for polycyclic aromatic hydrocarbon growth from reactions of either vinyl- or phenylacetylene with a phenyl radical are proposed and investigated using density functional theory (DFT). B3LYP/TZVP calculations are performed to obtain structures of minima and saddle points as well as kinetic data, supplemented with BMK/TZVP single-point energy calculations. The pathways include a cis-trans isomerization via a radicalic four-membered ring intermediate, which has so far not been considered in the literature. The DFT approach is validated against coupled-cluster calculations of a model system representing this intermediate. The coupled-cluster calculations include single and double excitations as well as perturbative corrections for connected triples and are performed in a correlation-consistent cc-pVTZ basis.