AbstractThe reaction of Au(OH)3 and trifluoromethanesulfonic acid (triflic acid) in the presence of M2CO3 (M = Li, Na, K, Rb) and Ag(CF3SO3), respectively, yielded yellow single crystals of M[Au(CF3SO3)4] (M = Li, Na, K, Rb, Ag). They exhibit the [Au(CF3SO3)4]– anion with the gold atom in a square‐planar coordination of four monodentate triflate ions. The structural characteristics of the anion are well reproduced by theoretical calculations that allowed also for a reliable assignment of observed IR energies. Charge compensation for the anions is achieved by different M+ counter cations. According to their coordination requirements different crystal structures are adopted. For M = Li, Na, the compounds are triclinic [M = Li/Na: triclinic, P$\bar{1}$, Z = 1, a = 509.92(2)/525.43(2), b = 854.08(3)/902.08(4), c = 1044.67(4)/1080.28(5) pm, α = 94.006(2)/104.367(2)°, β = 92.935(2)/93.602(3)°, γ = 93.841(2)/90.706(2)°, V = 452.12(3)/494.83(4) Å3] and octahedral coordination of the cations is observed. The monoclinic Ag[Au(CF3SO3)4] [C2/c, Z = 4, a = 2218.83(5), b = 499.19(1), c = 1751.73(4) pm, β = 104.736(1)°, V = 1876.43(7) Å3] shows the Ag+ ion in trigonal prismatic surrounding of oxygen atoms. A coordination number of eight is found for K[Au(CF3SO3)4] [orthorhombic, Pbcn, Z = 4, a = 904.32(4), b = 1050.64(4), c = 2120.71(9) pm, V = 2014.92(15) Å3] and also for Rb[Au(CF3SO3)4] [monoclinic, P21/n, Z = 4, a = 919.80(3), b = 2121.77(6), c = 1083.40(3) pm, β = 90.120(2)°, V = 2114.36(11) Å3]. In both cases the [MO8] polyhedra have dodecahedral shape. The thermal decomposition of selected compounds was monitored up to 1050 °C and shows that a mixture of elemental gold and the respective alkaline metal sulfate is the residue. For M = Ag elemental silver is formed instead of a sulfate.