SoylentNews

takyon writes:

Helium, an "inert" noble gas, can form bonds with sodium at high pressure:

It's a surprising finding, he says, because, on Earth, helium is a chemically inert and unreactive compound that eschews connections with other elements and compounds. The first of the noble gases, helium features an extremely stable, closed-shell electronic configuration, leaving no openings for connections. Further, Boldyrev's colleagues confirmed computationally and experimentally that sodium, never an earthly comrade to helium, readily bonds with the standoffish gas under high pressure to form the curious Na₂He compound. These findings were so unexpected, Boldyrev says, that he and colleagues struggled for more than two years to convince science reviewers and editors to publish their results.

Persistence paid off. Boldyrev and his doctoral student Ivan Popov, as members of an international research group led by Artem Oganov of Stony Brook University, published the pioneering findings in the Feb. 6, 2017, issue of Nature Chemistry [DOI: 10.1038/nchem.2716] [DX]. The USU chemists' participation in the project was supported by the National Science Foundation and the Ministry of Education and Science of the Russian Federation.

Boldyrev and Popov's role in the project was to interpret a chemical bonding in the computational model developed by Oganov and the experimental results generated by Alexander Goncharov of the Carnegie Institution of Washington. Initially, the Na₂He compound was found to consist of Na₈ cubes, of which half were occupied by helium atoms and half were empty. "Yet, when we performed chemical bonding analysis of these structures, we found each 'empty' cube actually contained an eight-center, two-electron bond," Boldyrev says. "This bond is what's responsible for the stability of this enchanting compound."

From the abstract: "We also predict the existence of Na₂HeO with a similar structure at pressures above 15 GPa."

Original Submission