LAUSR

Abstract The acid strength of the datively bound HF → AlX3 complexes (X H, F, N3, CH3, CH CH2, C CH, C6H5, CN, CF3, OF, SH, SF, NCO, NCS, OCF3, and OSF5) is evaluated on the basis of theoretical calculations employing ab initio methods. It is demonstrated that the resulting acidity of HF → AlX3 depends strongly on the electron affinity of the X substituents as the effectiveness of the electron density withdrawal from the HF component towards the AlX3 component is related to the ability of the HF → AlX3 complex to donate a proton.