Knowledge Bank

Electronic energies and structural parameters are reported for three electronic states of methylene amidogen, $CH2N$. The ground state, $X2B1$, may be represented schematically as [FIGURE] The two excited states occur by excitation of the non-bonding and pi-electrons on the nitrogen, leading to states with three electrons and one electron in the pi-orbitals. Interestingly, the observed excitation energies for transitions to these states differ by only $545cm-1$, whereas the same transition energies for the isoelectronic cation, $CH2O+$, differ more than 3 eV. We report adiabatic and vertical excitation energies for methylene amidogen and vertical excitation energies for $CH2O+$. The results of the calculations suggest that polarization of the electron distribution in $CH2O+$ leads to stabilization of the $1\pi$ state and destabilization of the $3\pi$ state, relative to the separation in the neutral molecule.