Donor–acceptor complexes of Lewis bases with bromine monochloride in the gas phase. Some generalisations from rotational spectroscopy

Abstract

Some properties of a series of donor–acceptor complexes B⋯BrCl determined from ground-state rotational spectra are shown to vary systematically with the Lewis base B, where B is CO, C₂H₂, C₂H₄, H₂S, HCN or NH₃. The behaviour of each of the properties (the intermolecular stretching force constant, k_σ, the intramolecular charge transfer, δe, from Br to Cl, and the angular geometry) is shown to parallel closely that in the corresponding series B⋯Cl₂. Although the B⋯BrCl are the more strongly bound, the Lewis base–halogen interaction in both series can be described as mainly electrostatic in origin.