TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The ionic liquid composition exhibits thermodynamic stability up to a temperature of approximately 375 degrees C, ionic conductivity of up to 10 mS/cm at room temperature, and a liquidus range of greater than 400 degrees C. Preferred Components: The phosphine based cation is ethyl-methyl-dipropyl-phosphonium, 1-ethyl-1-methyl-phospholanium, 1-ethyl-1-methyl-phosphinanium, 1-butyl-1-ethyl-phosphinanium, 1-butyl-1-ethyl-phospholanium, 1-methyl-1-phenyl-phosphinanium, 1-methyl-1-phenyl-phospholanium, 1,1-diphenyl-phosphinanium, 1,1-diphenyl-phospholanium, ethyl-methyl-diphenyl-phosphonium, dimethyl-diphenyl-phosphonium or (2-hydroxy-ethyl)-triphenyl-phosphonium. The anions are: 1NO3-/1O3SCF3, 3NO3-/1O3SCF3, 1NO3-/3O3SCF3, 1NO3-/1N(SO2CF3)2-, 1NO3-/1PF6-, 1O3SCF3-/1N(SO2CF3)2-, 1O3SCF3-/IO3SC6H4CH3-, 3O3SCF3-/1O3SC6H4CH3-, 1O3SCF3-/1O3SCF2CF2CF3-, 1O3SC6H4CH3-/3O3SCH3-, 1O3SC6H4CH3-/1O3SCF2CF2CF3-, 3O3SC6H4CH3-/1O3SCF2CF2CF3- or 1O3SC6H4CH3-/3O3SCF2CF2CF3-; and Br-, I-, -N(SO2)2CF3, -O3SCF3, -O2CCF3, -O2CCF2CF2CF3, -O3SC6H4CH3, CF3BF3-,C(CN)3-, PF6-, NO3-, -O3SCH3, -O3SC6H4CHCH2, BF4-, -O3SCF2CF2CF3, -SC(O)CH3, SO42-, -O2CCF2CF3, -O2CH, -O2CC6H5, -OCN or CO32-. Preferred Definitions:    R1-R4 = 2-14C-alkyl, aliphatic, aromatic or heterocyclic, preferably tetramethylene phospholane, pentamethylene phosphorinane, tetramethinyl phosphole, phospholane or phosphorinane.    EXAMPLE - Silver triflate was charged into a round bottom flask (50 ml) and assembled to a 3 cm swivel frit. The flask was evacuated and brought into a glove box. In the glove box, di-n-propyl ethyl methyl phosphonium iodide was added, re-assembled, and anhydrous tetrahydrofuran was vacuum transferred. The flask was allowed to warm to room temperature and then heated to 40 degrees C for 2 hours to form a light green bead-like solid. This solid was removed by filtration. This yielded a pearly, opalescent solution. Volatile materials were removed under high vacuum with heating using a 30 degrees C hot water bath. This resulted in a white crystalline material (comprising ethyl-methyl-dipropyl-phosphonium and trifluoro-methanesulfonic acid anion) with a yield of 0.470 g.