Anion photoelectron spectroscopy and ab initio calculations of the gas phase chloride–carbon monoxide complex: Cl−⋯CO

The first experimental anion photoelectron spectrum of the chloride–carbon monoxide complex is presented in combination with supporting ab initio calculations at the MP2 level of theory. The calculations reveal a previously unreported minimum for the neutral radical, namely the van der Waals Cl⋯OC linear complex. The experimental spectral feature is assigned to transitions from a Cl−⋯CO bent van der Waals complex to the linear Cl⋯CO neutral van der Waals radical. A stabilisation energy of 0.16 ± 0.01 eV is determined from the spectrum which is in line with the predicted cluster binding energies of 3.5 kcal mol−1 (0.15 eV) for the anion complex.