Mercury(II) anions derived from the F5TeO (teflate) group were synthesized and structurally characterized. The salts, [N(CH2CH3)(4)](2)[Hg(OTeF5)(4)], [N(CH3)(4)](3)[Hg(OTeF5)(5)], [N(CH2CH3)(4)](3)[Hg(OTeF5)(5)], [N(CH3)(4)](2)[Hg-2(OTeF5)(6)], Cs-2[Hg(OTeF5)(4)].Hg(OTeF5)(2), and {Cs-3[Hg-2(OTeF5)(7)].Hg(OTeF5)(2)}.4SO(2)ClF, were obtained by reaction of Hg(OTeF5)(2) with [M][OTeF5] (M = [N(CH3)(4)](+), [N(CH2CH3)(4)](+), Cs+) and were characterized by low-temperature single-crystal X-ray diffraction and low-temperature Raman spectroscopy. Unlike in the extensively fluorine-bridged solid-state structures of [HgF3]- and [HgF4](2), the less basic and more sterically demanding teflate ligands of the Hg(II) anions show less tendency to bridge. The anions exhibit a variety of structural motifs, ranging from well-isolated tetrahedral [Hg(OTeF5)(4)](2) and square-pyramidal [Hg(OTeF5)(5)](3) to the chain structures, [Hg-2(OTeF5)(6)](2) and [Hg-2(OTeF5)(7)](3).Hg(OTeF5)(2). The geometrical parameters and vibrational frequencies of [Hg(OTeF5)(4)](2) (S-4), [Hg(OTeF5)(5)](3) (C-1), and [Hg-2(OTeF5)(6)](2) (D-2) anions, as well as the hypothetical [Hg-3(OTeF5)(8)](2) (C-1) anion, were calculated using density functional theory methods (PBE1PBE/def(2)-TZVPP), which aided in the assignment of the Raman spectra of [Hg(OTeF5)(4)](2), [Hg(OTeF5)(5)](3), [Hg-2(OTeF5)(6)](2), and Cs-2[Hg(OTeF5)(4)].Hg(OTeF5)(2). The calculated geometries were used to assess the effects of solid-state interionic interactions on the anion geometries. For the most part, the gross gas-phase trigonal bipyramidal (tbp) geometry of [Hg(OTeF5)(5)](3) adheres to the predicted VSEPR geometry but contrasts with the solid-state anion structures, which have square-pyramidal geometries or geometries that lie between square pyramidal- and tbp-geometries. However, the bond length order calculated for the Hg-O bonds of tbp-[Hg(OTeF5)(5)](3), Hg-O-eq > Hg-O-ax, is opposite to that predicted by the VSEPR model of molecular geometry. Natural bond orbital analyses provided the associated Mayer bond orders, Mayer valencies, and natural population analysis charges.