[en] Experiments on gas-phase chemistry for chlorides have been conducted to clarify chemical properties of the first superheavy element, rutherfordium (Rf), Z = 104. However, adsorption enthalpies obtained in each experiment are not the same, even for those of the homologues Zr and Hf. In the present study, off-line isothermal gas chromatography was done using long-lived radioactive tracers to obtain reliable adsorption enthalpies for ZrCl₄ and HfCl₄ when adsorbed on a quartz glass surface. To simulate a column surface modified by a chlorinating reagent in on-line experiments, chromatography was also performed using a chlorinated column. A newly developed analytical method which is independent of experimental parameters and uncertain physical quantities was applied to determine the adsorption enthalpies. The obtained enthalpies for ZrCl₄ and HfCl₄ were -101.3 ± 4.0 kJ mol^-1 and -98.1 ± 3.1 kJ mol^-1 for the non-treated column, respectively, and those for the chlorinated column were -85.1 ± 4.5 kJ mol^-1 and -84.2 ± 3.3 kJ mol^-1, respectively. (author)

[en] An isothermal gas-chromatographic (IGC) device has been developed and tested for on-line gas phase studies of volatile oxychlorides of short-lived group-5 transition metals. Radioisotopes of niobium and tantalum, produced in nuclear fusion evaporation reactions, are directly flushed into the IGC setup by an inert gas-jet. Oxychloride compounds are formed by the addition of SOCl₂ and O₂. Parameters influencing the formation and transport of NbOCl₃ and TaOCl₃ are discussed. For nuclides with half-lives (t_1/2) of about 30 s, an overall efficiency of 7% is obtained, rendering the IGC setup suitable for the chemical exploration of ²⁶²Db (t_1/2 = 34 s).

[en] The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350-600 °C. Under the exactly same chemical conditions, comparative studies with the lighter homologues of Group 5 in the Periodic Table clearly indicate the volatility sequence being NbOCl${}_3$ > TaOCl${}_3$ ≥ DbOCl${}_3$. From the obtained experimental results, thermochemical data for DbOCl${}_3$ were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides. (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH)