Anion Exchange Behaviour of Zr, Hf, Nb, Ta and Pa as Homologues of Rf and Db in Fluoride Medium

Studies of the chemical property of transactinide elements are very difficult due to their short half-lives and extremely small production yields. However it is still possible to obtain considerable information about their chemical properties, such as the most stable oxidation states in aqueous solution, complexing ability, etc., comparing their behaviour with their lighter homologous in the periodic table. In order to obtain a better knowledge of the behavior of rutherfordium, Rf (element 104), dubnium, Db (element 105) in HF medium, the sorption properties of Zr, Hf, Nb, Ta and Pa, homologues of Rf and Db, were studied in NH4F/HClO4 medium in this work. Stability constants of the fluoride complexes of these elements were experimentally obtained from Kd obtained at different F- and H+ concentrations. The anionic complexes: [Zr(Hf)F5]-, [Zr(Hf)F6]2-, [Zr(Hf)F7]3-, [Ta(Pa)F6]-, [Ta(Pa)F7]2-, [Ta(Pa)F8]3-, [NbOF4]- and [NbOF5]2- are present as predominant species in the HF range over investigation.