Closing the Shell: Gas‐Phase Solvation of Halides by 1,3‐Butadiene

Abstract

Gas‐phase solvation of halides by 1,3‐butadiene has been studied via a combination of photoelectron spectroscopy and density functional theory. Photoelectron spectra for X−⋯(C4H6)n (X=Cl, Br, I where n=1‐3, 1–3 and 1–7 respectively) are presented. For all complexes, the calculated structures indicate that butadiene is bound in a bidentate fashion through hydrogen‐bonding, with the chloride complex showing the greatest degree of stabilisation of the internal C−C rotation of cis‐butadiene. In both Cl− and Br− complexes, the first solvation shell is shown to be at least n=4 ${n = 4}$ from the vertical detachment energies (VDEs), however for I−, increases in the VDE may suggest a metastable, partially filled, first solvation shell for n=4 ${n = 4}$ and a complete shell at n=6 ${n = 6}$ . These results have implications for gas‐phase clustering in atmospheric and extraterrestrial environments.