Electron affinity, gas-phase acidity, bond dissociation energy, and negative ion states of nitromethane

Published electron capture detector (ECD) data for nitromethane and alpha-nitrotoluene were analyzed using the nonlinear least-squares procedure. From this, the adiabatic electron affinities are 0.50 +/- 0.02 and 0.65 +/- 0.1 eV and the CN bond dissociation energies are 2.67 +/- 0.1 and 2.0 +/- 0.1 eV, respectively. Negative ion Morse potentials consolidate diverse data for nitromethane in both the CN and CPI dimensions. Curves for alpha-nitrotoluene were predicted by analogy to the nitromethane curves. Semiempirical multiconfiguration configuration interaction (AM1-MCCI) calculations support the above ECD values. For nitromethane, the calculated values are D(CH) = 4.42 eV, EA(CH(2)NO(2)) = 2.45 eV, and gas-phase acidity (GPA) = 15.4 eV. These agree with experimental literature values. Comparable predicted values for alpha-nitrotoluene are D(CH) = 3.8 eV, EA(C(7)H(6)NO(2)) = 2.4 eV, and GPA = 15.0 eV.