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

Abstract

The anion photoelectron spectra of Cl−⋅⋅⋅CD3CDO, Cl−⋅⋅⋅(CD3CDO)2, Br−⋅⋅⋅CH3CHO, and I−⋅⋅⋅CH3CHO are presented with electron stabilisation energies of 0.55, 0.93, 0.48, and 0.40 eV, respectively. Optimised geometries of the singly solvated species featured the halide appended to the CH3CHO molecule in‐line with the electropositive portion of the C=O bond and having binding energies between 45 and 52 kJ mol−1. The doubly solvated Cl−⋅⋅⋅(CH3CHO)2 species features asymmetric solvation upon the addition of a second CH3CHO molecule. Theoretical detachment energies were found to be in excellent agreement with experiment, with comparisons drawn between other halide complexes with simple carbonyl molecules.

Photoelectron Spectroscopy and High-Level Ab Initio Calculations of the Iodide–Methylperoxy Radical Complex

“…The E stab value also serves as a good proxy to infer the strength of the electrostatic interaction as these interactions dominate the binding of anion van der Waals complexes. By this metric, the iodide–methylperoxy complex ( E stab = 0.40 eV) is similarly bound compared to other iodide–molecule complexes, with values of 0.40, 0.41, 0.48, and 0.44/0.43 eV for I – ···CH 3 CHO, I – ···CH 2 O, I – ···(H 2 O)­(CH 3 CH 2 ), and I – ···CH 3 COCH 3 , , , respectively. I – ···(H 2 O)­(CH 3 CH 2 ) also corresponds in mass to CH 3 IO 2 – ; however, experiments where they have been observed required addition of these solvent molecules to the gas mixture in similar quantities as the halide precursor.…”

Halide–propene complexes: validated DSD-PBEP86-D3BJ calculations and photoelectron spectroscopy

“…Shift W1w (I À ) = À0.006 eV). 40,41 A summary of the resulting corrected and shifted VDEs is provided in Table 3 with all cartesian coordinates, geometries, VDEs, and harmonic frequencies provided in the ESI. † Included in Table 1, the DSD-PBEP86-D3BJ/AV(T,Q)Z energies are also extrapolated to the complete basis set limit using Helgaker's approach for completeness.…”

“…Shift W1w (I − ) = −0.006 eV). 40,41 A summary of the resulting corrected and shifted VDEs is provided in Table 3 with all cartesian coordinates, geometries, VDEs, and harmonic frequencies provided in the ESI †…”

A tale of two conformers: spectroscopic evidence for halide catalysed formic acid isomerisation

“…The relative agreement between experimentally determined photoelectron peaks and those determined based on high-level ab initio calculations has been demonstrated in previous publications. 34,35,39,40 The rotational barrier associated with conversion between syn-and anti-formic acid is also theoretically probed with respect to the relative barrier height and formic acid conformer energy difference, both associated with bare formic acid and following complex formation with a halide anion; showing a significant decrease in the barrier to formation of the anti-formic acid conformer and complete stabilisation of the anti-formic acid conformer post complex formation.…”