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

► First experimental photoelectron spectrum of the Cl−⋯CO complex, with stabilisation energy of 0.16 ± 0.01 eV. ► New minimum energy structure found for the neutral Cl⋯OC complex from ab initio calculations. ► Ab initio calculations agree with experimental spectrum, best overlap between anion and neutral van der Waals structures.