Structures of a trivalent actinium cation in helium clusters (Ac ⋅He ) have been studied by quantum path integral molecular dynamics simulations with different cluster sizes, n=18-200. The nuclear quantum effect of helium atoms plays an important role in the vibrational amplitude of the Ac -He complex at low temperatures (1-3 K) at which the complex is stable. We found that the coordination number of helium atoms comprising the first solvation shell can be as high as eighteen. In this case, the helium atoms are arranged in D symmetry. The Ac -He complex becomes more rigid as the cluster increases in size, which implies that it becomes more stable. The simulation results are based on an accurate description of the Ac -He interaction using relativistic ab initio calculations.

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 8C. 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.

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 NbOCl3 > TaOCl3 ≥ DbOCl3. From the obtained experimental results, thermochemical data for DbOCl3 were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides.

Die Gasphasenchemie des exotischen Transactinoids Dubnium und seiner leichteren Homologen Tantal und Niob wird in der Zuschrift auf S. 18015 von Nadine M. Chiera, Tetsuya K. Sato und Mitarbeitern beschrieben. Die Reihenfolge der Flüchtigkeit unter den Elementen der Gruppe 5, wie sie aus dem Verhalten ihrer Oxychloridverbindungen abgeleitet wird, stimmt mit dem Mendelejewschen Gesetz überein und etabliert Dubnium als eines der am wenigsten flüchtigen Elemente des Periodensystems.

Extreme gas-phase chemistry … …w ith the exotic transactinide dubnium and its lighter homologues tantalum and niobium is described by Nadine M. Chiera, Te tsuya K. Sato,a nd co-workers in their Communication on page 17871. Thesequence of volatility among Group 5elements,as deduced from the behavior of their oxychloride compounds,i si na greement with Mendeleevsl aw,e stablishing dubnium as one of the least volatile elements of the periodic table.