Treatment of K2Hg2Se3 or Na2HgSe2 in the nonclassical ionic liquid (EMIm)(SH) at 100 or 120 °C, respectively, yielded single crystals of K2Hg6Se7 (1) Na2Hg3S2.51Se1.49 (2), K2Hg3S1.03Se2.97 (3), and K2Hg3S2.69Se1.31 (4). Common synthesis routes like reactions in polychalcogenide flux, reactions under solvothermal conditions or ionothermal treatment in classical ionic liquids did not afford the title compounds, which only emerge from the described, mild pseudo-flux approach.