HgF4 is a diamagnetic, square planar molecule. The mercury atom has a formal 6s25d86p6 electron configuration, and as such obeys the octet rule but not the 18-electron rule. HgF4 is isoelectronic with the tetrafluoroaurate anion, , and is valence isoelectronic with the tetrachloroaurate (), tetrabromoaurate (), and tetrachloroplatinate () anions.
