Angular and radial geometries, charge transfer and binding strength in isolated complexes B⋯ICl: some generalisations

Generalisations about the nature of the interaction of simple Lewis bases with iodine monochloride are drawn from properties of complexes B⋯ICl (where B is Ar, N2, CO, C2H2, C2H4, HCN, H2O, H2S, PH3 or NH3) determined by rotational spectroscopy. Systematic behaviour in the radial and angular geometries, in the electron transfer (both intermolecular and within ICl) on formation of the complex, and in the binding strength (as indicated by the intermolecular stretching force constant kσ) is observed as B varies along the series. Comparisons with the properties of other complexes B⋯XY reveal interesting parallels between the series B⋯Cl2, B⋯BrCl, B⋯ClF and B⋯ICl.