Towards an Understanding of Halide Interactions with the Carbonyl-Containing Molecule CH3 CHO.

The anion photoelectron spectra of Cl- ⋅⋅⋅CD3 CDO, Cl- ⋅⋅⋅(CD3 CDO)2 , Br- ⋅⋅⋅CH3 CHO, and I- ⋅⋅⋅CH3 CHO 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 CH3 CHO 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- ⋅⋅⋅(CH3 CHO)2 species features asymmetric solvation upon the addition of a second CH3 CHO molecule. Theoretical detachment energies were found to be in excellent agreement with experiment, with comparisons drawn between other halide complexes with simple carbonyl molecules.