Co-ordination behaviour of dioxouranium(VI) nitrate in water–acetone mixtures

Abstract

Potentiometry using nitrate ion-selective electrodes, Raman, ¹H n.m.r. and u.v.–visible absorption spectroscopy have been used to study the co-ordination behaviour of dioxouranium(VI) nitrate in water–acetone mixtures over the complete solvent composition range. At the concentrations studied (up to 0.14 mol dm^–3) there was no evidence of UO₂²⁺–NO₃^– complexing in pure water, and the co-ordination species is believed to be [UO₂(H₂O)₅]²⁺. Complexing starts to occur above 60%(v/v) acetone–water, probably via a two-step equilibrium, and at high acetone concentrations the only significant complex species present is suggested to be [UO₂(NO₃)₂(H₂O)₂].