(a) Crystal structure of I4/m Li₄Au and Cmcm Li₅Au at 50 GPa. The Bader charge of Au in various Li_nAu (n = 1–5) compounds, showing that the negative oxidation state of Au is beyond −3 in Li₄Au and Li₅Au. (b) Crystal structures of I4/m AuF₄ and R-3 AuF₆; molecular orbital plots of Au 5d orbitals in I4/m AuF₄. Adapted with permission from Ref. [57]. Copyright (2018) American Chemical Society. (c) The two mixed-valence compounds C2/m AuO₂ and P-1 AuS. Adapted with permission from Ref. [58]. Copyright (2018) Wiley.