Chrysene resonance energy

Benzene rings can also be fused in angular fashion, as in phenanthrene, chrysene, and picene. These compounds, while reactive toward additions in the center ring, retain most of the resonance energy per electron (REPE) stabilization of benzene and naphthalene. ... 

Chia and Simmons388 calculated the resonance energies (ER)20 of four mono- and dibenzotetraazapentalenes (Scheme 24). Values are comparable with those of o-condensed aromatic systems (naphthacene, ER = 110 kcal mol-1 chrysene, ER = 116.5 kcal mol-1), and, like these carbocyclic systems, angularly-shaped molecules are more stable than linear ones. HMO calculations of delocalization energies (DE) show that the tetraazapentalene structure 15 is more stable than the tetra-azacyclooctatetraene valence isomer 324 (Scheme 14, Section IV,B,2) whether 324 is planar or tub-shaped. Calculations of electrophilic reactivity (Section IV,C,4,d), electronic spectra (by the PPP method employing all singly excited configurations), and bond orders have been carried out, and they confirm the aromatic nature of these systems. 

Anthracene and phenanthrene are isomeric compounds with three fused benzene rings. Their resonance energies are calculated to be 84 kcal/niol (352 kJ/mol) and 92 kcal/mol (385 kJ/mol), respectively. Many other polycyclic aromatic hydrocarbons are known. Chrysene and benzo[a]pyrene are typical examples. 

Kurihara T, Motohashi N, Gui-Lin Pang, Higano M, Kiguchi K, Molnar J (1996) Correlation between topological resonance energy of methyl-substituted Benz[c] acridines, Benzo [a] phenothiazines and Chrysenes, and their carcinogenic or antitumor ac-tivites. Anti cancer Res 16 2757-2766... 

The phenanthrene and chrysene structures could be derived from cyclic terpenoids such as abietic acid, sterols, and hopanes (34). Although tri-phenylene, which has the highest resonance energy among the four-ring catacondensed PAHs (35), was not present in the SRC II HD at a significant level, this compound was found in the coal tar which is a higher temperature... 

Although the abundances of the benzofluoranthene isomers are consistent with their resonance energies, other factors must be considered when comparing other isomer pairs. For example, in comparing benzo[a]pyrene with benzo[e]pyrene, benzo[a]pyrene is the less resonance-stable isomer but is the one that can be formed most easily from the biologically derived chrysene or benz[fl]anthracene. In this case, benzo[fl]pyrene is the most abundant isomer of the two in the coal tar. No universal rules can explain all observations only general trends can be indicated. 

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