Electron Affinity, Gas-Phase Acidity, Bond Dissociation Energy, and Negative Ion States of Nitromethane

Published electron capture detector (ECD) data for nitromethane and α-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 CH dimensions. Curves for α-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 α-nitrotoluene are D (CH) = 3.8 eV, EA(C 7 H 6 NO 2 ) = 2.4 eV, and GPA = 15.0 eV.