Negative Ion Photoelectron Spectroscopy of P₂N₃⁻: Electron Affinity and Electronic Structures of P₂N₃˙

We report here a negative ion photoelectron spectroscopy (NIPES) and ab initio study of the recently synthesized planar aromatic inorganic ion P₂N₃⁻, to investigate the electronic structures of P₂N₃⁻ and its neutral P₂N₃ radical. The adiabatic detachment energy of P₂N₃⁻ (electron affinity of P₂N₃) was determined to be 3.765 ± 0.010 eV, indicating high stability for the P₂N₃⁻ anion. Ab initio electronic structure calculations reveal the existence of five, low-lying, electronic states in the neutral P₂N₃ radical. Calculation of the Franck-Condon factors (FCFs) for each anion-to-neutral electronic transition and comparison of the resulting simulated NIPE spectrum with the vibrational structure in the observed spectrum allows the first four excited states of P₂N₃ to be determined to lie 6.2, 6.7, 11.5, and 22.8 kcal mol⁻¹ above the ground state of the radical, which is found to be a 6π-electron, ²A₁, σ state.National Science Foundation (U.S.) (Grant CHE-136211