Enthalpies of formation of nitromethane and nitrobenzene: Theory vs experiment

Enthalpies of formation of gaseous nitromethane and nitrobenzene are calculated by Gaussian-4 method with the use of isogyric and isodesmic reactions. Of the two widely-used experimental values for nitromethane (−74.5 and −81.0 kJ · mol−1), the calculations provide strong support for the first one. The cited experimental values of enthalpy of formation of nitrobenzene (67.5 and 68.5 kJ · mol−1) are based on the only calorimetric investigation; the both these values look to be a somewhat overestimated when compared with the average result (62.8 kJ · mol−1) obtained from 95 isogyric and isodesmic reactions with 26 reference nitro compounds involved. The purpose of the present work is to attract attention of experimentalists to new experimental investigation of nitrobenzene, and probably nitromethane as well.

► Nitro compounds poses a challenging problem not only for experiment, but also for theory.
► Calculation of enthalpies of formation of nitromethane and nitrobenzene by G4 method using isodesmic reactions.
► New measurements of enthalpy of formation of nitrobenzene would be extremely valuable.