A Joint Experimental and Computational Study of the Negative Ion Photoelectron Spectroscopy of the 1-Phospha-2,3,4-triazolate Anion, HCPN₃^–

Abstract

We report here the results of a combined experimental and computational study of the negative ion photoelectron spectroscopy (NIPES) of the recently synthesized, planar, aromatic, HCPN 3 − ion. The adiabatic electron detachment energy of HCPN 3 − (electron affinity of HCPN 3 •) was measured to be 3.555 ± 0.010 eV, a value that is intermediate between the electron detachment energies of the closely related (CH) 2 N 3 − and P 2 N 3 − ions. High level electronic structure calculations and Franck−Condon factor (FCF) simulations reveal that transitions from the ground state of the anion to two nearly degenerate, low-lying, electronic states, of the neutral HCPN 3• radical are responsible for the congested peaks at low binding energies in the NIPE spectrum. The best fit of the simulated NIPE spectrum to the experimental spectrum indicates that the ground state of HCPN 3• is a 5π-electron 2 A″ π radical state, with a 6π-electron, 2 A′, σ radical state being at most 1.0 kcal/mol higher in energy.Article pubs.acs.org/JPCA

Simulation of Negative Ion Photoelectron Spectroscopy Using a Nuclear Ensemble Approach: Implications from a Nuclear Vibration Effect

“…The D 0 electronic state consists of π-character N−N and N−P−C bonding interactions while the D 1 state of significant σ (anti)bonding characters of whole ring bonds. Thus, the energy ordering of lowest two electronic states of HCPN 3 − is altered compared to that of P 2 N 3 − , that is in line with the finding by Hou et al 16 Interestingly, through analyzing the DOs based on the other ten sampled nuclear configurations (Figure S5b), the characters for D 2 (σ), D 3 (π), and D 4 (σ) states of HCPN 3 − were found to be almost not affected. But the main characters for D 0 and D 1 were sensitive to the nuclear vibration, and the first two doublet states should be considered to possess a mixture of π and σ electrons.…”

“…It can further quantitatively produce detachment energy with sufficient accuracy, that can provide reliable benchmarks to test theoretical methods. As an important complement to the experimental NIPES measurements, theoretical simulation based on accurate ab initio calculations ,− provides a comprehensive atomic or molecular-level characterization of electronic structures and intra/intermolecular interactions for anionic molecules and clusters. It will certainly be of great importance to provide results directly comparable to experimental measurements.…”

“…HCPN 3 – has a similar electronic structure but quite different spectral feature compared to P 2 N 3 – (Figure i). These systems were chosen because a series of consistent experimental NIPES are available for comparison taken from the work of Wang et al ,, Further, the ionization information related to DOs were analyzed. The vibrational distributions and main vibration modes were also plotted to reveal the influence of a nuclear vibration effect.…”

“…NIPES of NaS 5 – , P 2 N 3 – , and HCPN 3 – : (a, e, i) experimentally determined ones using the detachment laser of 193 nm taken from the work of Wang et al; ,, (b, f, j) simulated ones using NEA with a sampling number of points (NP) of nuclear coordinates of 500; (c, g, k) simulated ones based on their equilibrium structures (NP = 1); and (d, h, l) simulated ones based on the DOS method and the spectrum were shifted by +0.68 eV for NaS 5 – , by +2.1 eV for P 2 N 3 – and by +2.2 eV for HCPN 3 – , respectively.…”

Magnetic-Bottle and velocity-map imaging photoelectron spectroscopy of APS− (A=C14H10 or anthracene): Electron structure, spin-orbit coupling of APS•, and dipole-bound state of APS−

“…This strategy has led to successful syntheses of novel inorganic aromatic molecules such as P 2 N 3 − [15] and HCPN 3 − [19], as well as an astrophysically interesting species HCP [19]. The electronic structures of HCPN 3 − and P 2 N 3 − have been subsequently investigated using gas phase negative ion photoelectron spectroscopy (NIPES) coupled with an electrospray ionization source (ESI) [21,22].…”