Photoelectron Spectroscopy and Structures of X^- ⋅⋅⋅CH₂ O (X=F, Cl, Br, I) Complexes

A combined experimental and theoretical approach has been used to investigate X^- ⋅⋅⋅CH₂ O (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^- ⋅⋅⋅CH₂ O, Br^- ⋅⋅⋅CH₂ O, and I^- ⋅⋅⋅CH₂ O species. Additionally, high-level CCSD(T) calculations found a C_2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F^- ⋅⋅⋅CH₂ O was also studied theoretically, with a C_s hydrogen-bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH₂ O complexes, with the results of potential interest to atmospheric CH₂ O chemistry.