Ion–water interactions in pyridine solutions studied by proton magnetic resonance

Abstract

Proton resonance shifts of water-poor (0.1 mol kg^–1) pyridine solutions containing LiClO₄, LiCl, LiNO₃, LiBr, LiI, NaClO₄, NaI, NaBPh₄, NaSCN, Bu₄NBr and Et₄NClO₄ have been measured at 35 °C. The downfield shifts of the water proton were first interpreted in terms of the formation of M(H₂O)⁺ species. A second approximation assumes the existence of a water-separated ion pair (M⁺H₂OA^–). The experimental results and the calculated chemical shifts given by the Buckingham equation are compared.