The proposed omnicapped truncated tetrahedral structure of the recently reported Au-20 cluster can be generated from a regular dodecahedron by forming two transannular Au-Au bonds across each face while preserving Tsymmetry. An electron-precise chemical bonding scheme accounts for the large band gap (1.77 eV) of Au-20 and relates its structure to that of titanacarbohedrene Ti8C12 and Os-20(CO)(40)(2-).