Mercury Induced by Pressure to act as a Transition Metal in Mercury Fluorides

The question of whether Hg is a transition metal remains open for stable solids. In our work we propose that high-pressure techniques will help prepare unusual oxidation states[1] of Hg in Hg-F compounds. By means of \textit{ab initio} calculations and an advanced structure-search algorithm we find that under high pressure charge is transferred from the Hg d orbitals to the F, and becomes a transition metal.[2] HgF$_3$ and HgF$_4$ have been found to be stable compounds at high pressure. HgF$_4$ consists of planar molecules, a typical geometry for d$^8$ metallic centers. HgF$_3$ is an example of metallic and ferromagnetic compound, with an electronic structure analogous to transparent conductors due to the Hg d$^9$ configuration. \begin{thebibliography}{} \bibitem{csf} M.-S. Miao, Nat. Chem. \textbf{5}, 846 (2013) \bibitem{hgf} J. Botana, X. Wang, C. Hou, D. Yang, H. Lin, Y. Ma, M.-S. Miao, Angew. Chem. Int. Edit. \textbf{54}, 9280 (2015). \end{thebibliography}