Nature of complexes B … ClF in the gas phase: Conclusions from systematic variation of the Lewis base B and a comparison of the B … ClF/B … HCl series.

General conclusions concerning the nature of the B … ClF interaction follow from the behaviour of the properties of sixteen gas-phase complexes as the Lewis base B varies. Electric charge redistribution within ClF is small for most B … ClF considered (Mulliken outer complexes) but examples of the inner type [BCl]+ … F− having significant charge transfer are identified. Angular geometries in the series B … ClF and B … HCl are strikingly parallel. However, when the symmetry is Cs, the Z … HCl systems (Z = acceptor atom) are significantly nonlinear while the Z … Cl-F are all nearly collinear. Rules for predicting angular geometries in B … HCl are refined and extended to B … ClF.