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, kσ, 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.