The thermochemical properties of benzvalene, dihydrobenzvalene, and cubane were determined using ab initio molecular orbital calculations at the G2, G2(MP2), and G2(MP2,SVP) levels of theory. The enthalpy of formation, ΔfH°298, was examined with the use of homodesmic and isodesmic reactions. Based on the present theoretical calculations and available literature data, it is proposed that ΔfH°298 = 92 ± 2 kcal/mol for benzvalene and 55 ± 2 kcal/mol for dihydrobenzvalene. It is concluded that the discrepancy in the ΔfH°298 value of cubane, both experimentally and theoretically, warrants further experimental investigation. The heat capacity and entropy of benzvalene and dihydrobenzvalene were estimated on the basis of HF/6-31G(d) geometry and scaled harmonic frequencies. The adiabatic flame temperature was computed for each compound burning in air at 1 atm pressure using the estimated thermochemical data and compared with common hydrocarbon fuels. Consequently suitable surrogate fuels are identified for the characterization of global combustion processes of benzvalene, dihydrobenzvalene, cubane, and their derivatives.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry