Figure 3. Optimized structures with atom numbering and relative energies (kcal mol-1; in parenthesis, ZPE-corrected values) for the most important stationary points for the gas-phase reaction H2N+=CH2 + HCOOH¢ªH2N+-CH2-COOH (3) computed at the B3LYP/6-31++G(d,p) level of theory.