Ab initio calculations of coronene and other benzenoid aromatic hydrocarbons at the SCF, MP2, and densityfunctional
levels are used to estimate the gas-phase ∆Hf° of coronene. The results obtained show that the
best improvement over the SCF ∆Hf° is obtained using the correlation-corrected B3LYP density-functional
method, while the MP2 results appear to make agreement with the experimental value worse. The B3LYP/
6-311G** ∆Hf° of coronene and benzo[ghi]perylene are 71.8 and 73.2 kcal/mol. The computed proton and 13C NMR chemical shifts of coronene are in good agreement with experiment. The calculated nucleusindependent
chemical shifts (NICS) suggest that the central ring of coronene has diminished aromatic character,
but the peripheral rings are fully aromatic. For benzo[ghi]perylene, the NICS values reveal that only three
of the five peripheral rings are fully aromatic. The magnetic susceptibility of coronene shows a large
exhaltation, Λ, relative to a nonaromatic model system. Thermal and magnetic properties show a small
additional aromatic character in coronene over and above model systems.