STUDIES OF TITANIUM(IV) CHLORIDE IN A STRONGLY LEWIS ACIDIC MOLTEN-SALT - ELECTROCHEMISTRY AND TITANIUM NMR AND ELECTRONIC SPECTROSCOPY

The electrochemistry of titanium(IV) has been examined in acidic (AlCl3-rich) compositions of the ambient-temperature molten salt, AlCl3-1-ethyl-3-methylimidazolium chloride (ImCl). Titanium is reduced to Ti(III) and Ti(II) in two one-electron steps, both of which exhibit slow electron-transfer kinetics. The 49Ti NMR spectra for TiCl4 and AlCl3-rich melts exhibit a resonance at -4 ppm (49Ti = 0 ppm for neat TiCl4). In basic (chloride-rich) melts, the 49Ti resonance for TiCl62- is found at -237 ppm. In acidic melts, Ti(IV) is alkylated upon addition of Me3Al2Cl3 and is slowly reduced to Ti(III). Combination of TiCl4 and Me3Al2Cl3 in an acidic melt is demonstrated to be a catalytic system for ethylene polymerization. © 1990, American Chemical Society. All rights reserved.