Negative ion photoelectron spectroscopy of P(2)N(3)(–): electron affinity and electronic structures of P(2)N(3)˙

We report here a negative ion photoelectron spectroscopy (NIPES) and ab initio study of the recently synthesized planar aromatic inorganic ion P(2)N(3)(–), to investigate the electronic structures of P(2)N(3)(–) and its neutral P(2)N(3)˙ radical. The adiabatic detachment energy of P(2)N(3)(–) (electron affinity of P(2)N(3)˙) was determined to be 3.765 ± 0.010 eV, indicating high stability for the P(2)N(3)(–) anion. Ab initio electronic structure calculations reveal the existence of five, low-lying, electronic states in the neutral P(2)N(3)˙ 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 P(2)N(3)˙ 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, (2)A(1), σ state.