A FAST-ATOM-BOMBARDMENT MASS-SPECTROMETRIC STUDY OF ROOM-TEMPERATURE 1-ETHYL-3-METHYLIMIDAZOLIUM CHLOROALUMINATE(III) IONIC LIQUIDS - EVIDENCE FOR THE EXISTENCE OF THE DECACHLOROTRIALUMINATE(III) ANION

Previous studies of 1-ethyl-3-methylimidazolium chloride-aluminium(III) chloride ([emim]Cl-AlCl3) ionic liquids have been hampered by significant contamination of these liquids by oxide impurities. Treatment of these liquids with phosgene removes the oxide impurities, and the use of a specially constructed sample inlet system for air-sensitive materials permitted them to be studied by fast atom bombardment mass spectrometry. The ions Cl-, [Cl2]-, [AlCl4]-, [Al2Cl7]-, [emim]+ and [(emim)2X]+ (X = Cl or AlCl4) were observed for the bask ionic liquid. In addition, the anion [Al3Cl10]- was observed for the acidic composition. Within the mass spectrometer, the hydrolyses of [Al3Cl10]- to produce [Al3Cl8O]- and of [Al2Cl7]- to produce [Al2Cl5O]- were observed. Comparison of these results with published O-17 NMR data suggests that the primary hydrolysis products in acidic ionic liquids are [Al3Cl8O]- and [Al2Cl5O]- and that the principal secondary hydrolysis product is [Al2Cl6(OH)]-.