Scientists study superheavy elements for extraction methods

Advancing superheavy-element chemistry—the study of elements with an atomic number greater than 103—is a challenging task because of their scarce production rates and relatively short half-lives (i.e., less than 1 minute for most), thus requiring studies to be performed at the atom-at-a-time scale. The properties of these elements are linked to the physics and chemistry at the end of the periodic table. The periodic table is an arrangement of elements into chemical groups of similar chemical properties and the initial location of the superheavy elements on the periodic table are based solely on their proton number. Due to relativistic effects, many of the heavier transactinides (superheavy elements) are predicted to behave vastly different from their lighter group members, and therefore, may not belong in that group of the periodic table.

The only way to assign the true placement of superheavy elements in the periodic table is through studying their chemical properties. In a recent study, LLNL scientists were particularly interested in mercury(II)—Hg(II)—because it is the heaviest homolog (i.e., element from the same group) of copernicium(II)—Cn(II). The unsaturated hexathia-18-crown-6 (UHT18C6) molecule was investigated for the extraction of a Hg(II) and an experimental and computational study was performed to understand the bonding between Hg(II) and UHT18C6, as well as to predict the stability of the Cn(II)/UHT18C6 complex. In theory, if Cn(II) truly belongs to group 12 of the periodic table, then the extraction methods used on Hg(II) will work in future experiments with Cn(II).

This research may even be used to help with environmental remediation, as Hg is tied to environmental concerns. Additionally, Hg has been studied as a potential radiopharmaceutical, and these extraction methods may be used to rapidly remove radio-hg from targets for eventual use as diagnostic and therapeutic agents.

This work was funded by LLNL’s Laboratory Directed Research and Development Program under Project 19-ERD-003.

[M.G. Ferrier, C.A. Valdez, S.K. Singh, S. Hok, D. Ray, L. Gagliardi, J.D. Despotopulos, Unsaturated Sulfur Crown Ethers Can Extract Mercury(II) and Show Promise for Future Copernicium(II) Studies: A Combined Experimental and Computational Study, Inorganic Chemistry (2022), doi: 10.1021/acs.inorgchem.1c01869]