Photoelectron spectroscopy of hydrated hexafluorobenzene anions

Abstract

We present a synergetic experimental/theoretical study of hydrated hexafluorobenzene anions. Experimentally, we measured the anion photoelectron spectra of the anions, C6F6(-)(H2O)n (n=0-2). The spectra show broad peaks, which shift to successively higher electron binding energies with the addition of each water molecule to the hexafluorobenzene anion. Complementing these results, we also conducted density functional calculations which link adiabatic electron affinities to the optimized geometric structures of the negatively charged species and their neutral counterparts. Neutral hexafluorobenzene-water complexes are not thought to be hydrogen bonded. In the case of C6F6(-)(H2O)1, however, its water molecule was found to lie in the plane of the hexafluorobenzene anion, bound by two O-H...F ionic hydrogen bonds. Whereas in the case of C6F6(-)(H2O)2, both water molecules also lie in the plane of and are hydrogen bonded to the hexafluorobenzene anion but on opposite ends. This study and that of Schneider et al. [J. Chem. Phys. 127, 114311 (2007), preceding paper] are in agreement regarding the geometry of C6F6(-)(H2O)1.

Evidence of Electron Capture of an Outgoing Photoelectron Wave by a Nonvalence State in (C6F6)n–

“…The spectral width of the D 0 + hv → S 0 + e – channel is consistent with previous PE spectroscopy studies by the Kaya and Bowen groups and arises from the large structural change upon photodetachment from the buckled D 0 valence ground state of C 6 F 6 – ( C 2 v symmetry) to the planar S 0 ground state of neutral C 6 F 6 ( D 6 h symmetry). Both the T 1 and T 2 states of the neutral have buckled geometries that are more similar to that of the D 0 anion state, and vibrational structure can be seen in the PE features (ii) and (iii) (see Supporting Information).…”

“…14 This is of course not surprising given that the Franck-Condon overlap between anion and the neutral ground states is poor. 23,27 Figure 1(b) to (e) show the 2D-PE spectra for (C6F6)n − with n = 2 to 5, respectively. For n = 3 to 5, we have taken fewer PE spectra because of their reduced abundance in the molecular beam.…”

Ultrafast dynamics of low-energy electron attachment via a non-valence correlation-bound state

“…24 This change is associated with a steep increase in the electron binding energy. At the minimum energy geometry of C6F6 -, the vertical and adiabatic binding energy are 1.45 and ~0.5 eV, respectively, [39][40][41] excluding the additional binding that arises from the cohesion energy of C6F6to I. Hence, for a probe photon with hv = 1.55 eV, we anticipate a reduced photoelectron yield at the minimum buckled geometry of I•C6F6 -.…”

Substituent‐Stabilized Organic Dianions in the Gas Phase and Their Potential Use as Electrolytes in Lithium‐Ion Batteries

“…All of these molecules have C 2 v symmetry. We were interested to determine where the excess electron locates in BC 5 F 6 2− , that is, whether it locates at the hexagonal ring as in nonplanar C 6 F 6 − , or if it locates at the C−substituent σ* bond as in C 6 F 5 I − . In order to investigate this, we performed natural bond analysis (NBO) calculations.…”

“…First, we replaced all Hatoms with F. The equilibrium geometries of neutral and chargedB n C 6Àn F 6 (n = 0, 1, 2) are shown in Figure 1. The average CÀBb ond lengthsa re 1.55, 1.51, and 1.51 for the BC 5 F 6 neutral, anion andd ianion, respectively.A ll of these molecules have C 2v symmetry.W ew erei nterested to determine where the excesse lectron locates in BC 5 F 6 2À ,t hat is, whether it locates at the hexagonal ring as in nonplanar C 6 F 6 À , [19] or if it locates at the CÀsubstituent s*bond as in C 6 F 5 I À . [20] In order to investigate this, we performed natural bond analysis( NBO) calculations.…”