Antimony halides as solvents. Part V. Polycyclic aromatic hydrocarbons as Lewis bases in antimony trichloride solution

Abstract

Several polycyclic aromatic hydrocarbons R are shown, by conductance, to ionise thus: R + 2SbCl₃⇌(R·SbCl₂⁺)+ SbCl₄^–; the hydrocarbon acts as a Lewis base towards the sextet solvent-cation. Equilibrium constants are evaluated, which correlate closely with refined molecular orbital theory and with data for the proton-basicity R + HF ⇌ RH⁺+ F^–. The results also support the qualitative predictions of the ‘hard–soft’ acid–base theory.