The hydrogen fluoride solvent system. Part V. Solutions of SeF4 and SeF4,BF3

Abstract

Conductimetric measurements show that selenium tetrafluoride is a weak base in liquid hydrogen fluoride having an ionization constant of 4 × 10^–4. The adduct SeF₄,BF₃ ionizes in hydrogen fluoride but the solutions have a considerably lower conductivity than those of SF₃⁺BF₄^–; it is concluded that SeF₄,BF₃ is both polymeric and incompletely ionized in solution in HF. The ¹⁹F n.m.r. chemical shift of SeF₄,BF₃ in solution in HF, the ⁷⁷Se–¹⁹F coupling constant and the isotopic shift of the ¹⁹F resonance in ⁷⁷SeF₄,BF₃ have been determined and are discussed.