Single crystals of anhydrous dimercury(I) monofluorophosphate(V), Hg(2)PO(3)F (1), were obtained by cooling diluted aqueous Hg(2)(NO(3))(2) and (NH(4))(2)PO(3)F solutions from 85 degrees C to room temperature. Compound 1 crystallizes with eight formula units in the orthorhombic space group Ibam (No. 72) and lattice parameters a = 9.406(2) A, b = 12.145(3) A, c = 8.567(2) A. It adopts a new structure type even though a topological relation with dimercury(I) sulfate, Hg(2)SO(4), is established. The crystal structure of 1 (R(F(2) > 2sigma(F(2)) = 0.0353) exhibits Hg(2)(2+) dumbbells and discrete PO(3)F(2)(-) anions as single building units which are organized in a layered assembly parallel to (100). The symmetric Hg(2)(2+) dumbbell shows a typical Hg-Hg distance of 2.5051(9) A, and for each Hg atom, three Hg-O distances are found, ranging from 2.327(6) to 2.476(5) A. No interactions between Hg and F atoms are realized. The latter is exclusively bonded to the phosphorus atom at a distance d(P-F) = 1.568(8) A which is considerably longer than the P-O distances with a mean of 1.515 A. Compound 1 was further characterized by vibrational spectroscopy (Raman and IR) in the spectral range between 4000 and 50 cm(-)(1), thermal analysis (TG, DSC) up to 650 degrees C which revealed Hg(2)(P(2)O(7)) and Hg(3)(PO(4))(2) as thermal decomposition products, and (19)F and (31)P solid-state NMR spectroscopy. The value for the P-F coupling constant in 1 is J(PF) = -1072 Hz at 20 degrees C. The absolute sign of J(PF) is negative.