Gas-Phase Heat of Formation Values for Buckminsterfullerene (C₆₀), C70 Fullerene (C₇₀), Corannulene, Coronene, Sumanene, and Other Polycyclic Aromatic Hydrocarbons Calculated Using Density Functional Theory (M06 2X) Coupled with a Versatile Inexpensive Group-Equivalent Approach

A straightforward procedure using density functional theory (M06 2X) coupled with a group-equivalent approach is described that was used to calculate gas-phase heat of formation (Δ_f<i>H</i>°_g,298) values for buckminsterfullerene (C₆₀), C70 fullerene (C₇₀), corannulene, coronene, and sumanene. This procedure was also used to calculate exceptionally accurate Δ_f<i>H</i>°_g,298 values for a variety of single-ring aromatic and 2–7 ring polycyclic aromatic hydrocarbons (PAHs) as well as a large selection of other hydrocarbons and phenols. The approach described herein is internally consistent, and results for C₆₀, C₇₀, corannulene, coronene, and sumanene are in very close agreement with results reported by others who used higher-level computational theory. Statistical analysis of a test set containing benzene and 18 two to seven ring PAHs demonstrated that by using this approach a mean absolute deviation (MAD) and a root-mean-square deviation (RMSD) of 0.8 and 1.3 kJ/mol, respectively, were achieved for reference/experimental Δ_f<i>H</i>°_g,298 values versus calculated/predicted Δ_f<i>H</i>°_g,298 values. For statistical analysis of a larger test set containing 235 aromatic and aliphatic hydrocarbons and phenols, a MAD and a RMSD of 1.2 and 1.9 kJ/mol, respectively, were achieved for reference/experimental Δ_f<i>H</i>°_g,298 values versus calculated/predicted Δ_f<i>H</i>°_g,298 values