Crystal structures of (a) Fm-3m HgF₃ at 100 GPa. (b) I4/m HgF₄ at 50 GPa. (c) R-3 IrF₈ at 200 GPa. Adapted with permission from Ref. [85]. Copyright (2019) American Chemical Society. (d) R-3 IF₈ at 300 GPa.