Photoelectron Spectroscopy and Structures of X⁻⋅⋅⋅CH₂O (X=F, Cl, Br, I) Complexes

Abstract

A combined experimental and theoretical approach has been used to investigate X−⋅⋅⋅CH2O (X=F, Cl, Br, I) complexes in the gas phase. Photoelectron spectroscopy, in tandem with time‐of‐flight mass spectrometry, has been used to determine electron binding energies for the Cl−⋅⋅⋅CH2O, Br−⋅⋅⋅CH2O, and I−⋅⋅⋅CH2O species. Additionally, high‐level CCSD(T) calculations found a C2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F−⋅⋅⋅CH2O was also studied theoretically, with a Cs hydrogen‐bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH2O complexes, with the results of potential interest to atmospheric CH2O chemistry.

Spectroscopic Investigation of Chalcogen Bonding: Halide–Carbon Disulfide Complexes

“…The spectrometer used to acquire the time‐of‐flight anion photoelectron spectra presented here has been described in detail previously [30–32] . Details associated with the experimental and computational methods have been provided in the Supporting Information.…”

Towards an Understanding of Halide Interactions with the Carbonyl‐Containing Molecule CH3CHO

“…This is perhaps rather unexpected given the D 0 of I − ⋅⋅⋅CH 2 O has been reported as 43.2 kJ mol −1 , [37] while the D 0 of I − ⋅⋅⋅CH 3 CHO is presented here as 45.5 kJ mol −1 . For comparison, Cl − ⋅⋅⋅CH 3 CHO is more stable than Cl − ⋅⋅⋅CH 2 O by 2.2 kJ mol −1 and incurs an E stab increase of 0.04 eV.…”

“…In previous work, the 2 P 3/2 photodetachment peak of I − ⋅⋅⋅CH 2 O is predicted at 3.46 eV from CCSD(T)/CBS calculations, corresponding to a 0.40 eV E stab [37] . In this work, the 2 P 3/2 photodetachment of I − ⋅⋅⋅CH 3 CHO is reported as 3.47 eV from CCSD(T)/CBS results: a predicted E stab of 0.41 eV.…”

“…The current work bridges the gap between previous anion photoelectron spectroscopic studies involving halide anion complexes with simple carbonyl‐containing molecules; namely, CH 2 O and CH 3 COCH 3 [37,38] . As such, a summary of experimental E stab values and computational D 0 energies has been compiled in Table 2.…”

“…Computational work is presented to complement the experimental results, with geometries and predicted detachment energies used to rationalise the electronic structure. Furthermore, the results will be compared to previous studies involving CH 2 O [37] and CH 3 COCH 3 [38] in order to establish general trends observed for halide‐carbonyl molecule systems.…”