Negative ion photoelectron spectroscopy of P[subscript 2]N[subscript 3]−: electron affinity and electronic structures of P[subscript 2]N[subscript 3]˙

Abstract

We report here a negative ion photoelectron spectroscopy (NIPES) and ab initio study of the recently synthesized planar aromatic inorganic ion P[subscript 2]N[subscript 3]−, to investigate the electronic structures of P[subscript 2]N[subscript 3]− and its neutral P[subscript 2]N[subscript 3]˙ radical. The adiabatic detachment energy of P[subscript 2]N[subscript 3]− (electron affinity of P[subscript 2]N[subscript 3]˙) was determined to be 3.765 ± 0.010 eV, indicating high stability for the P[subscript 2]N[subscript 3]− anion. Ab initio electronic structure calculations reveal the existence of five, low-lying, electronic states in the neutral P[subscript 2]N[subscript 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[subscript 2]N[subscript 3]˙ to be determined to lie 6.2, 6.7, 11.5, and 22.8 kcal mol[superscript −1] above the ground state of the radical, which is found to be a 6π-electron, [superscript 2]A[subscript 1], σ state.