On the possible solvation of tetraalkyl-ammonium cations and tetraphenyl-boron anions by water

Abstract

Evidence of the extent of hydration of halide ions in aqueous solutions is discussed, and it is concluded that a primary solvation number of ca. 6 is correct. A recent suggestion that two different ways of describing this interaction, namely the "‘hydration number’' ca. 2–3, and the "‘coordination number’' ca. 6, does not seem to be desirable. It is suggested that neither R₄N⁺ nor BPh₄^- ions are actively solvated in water. Instead, the vibrational spectral changes often associated with these ions are interpreted in terms of changes in the concentration of free O–H groups. These changes are caused by active solvation of the gegen ions.