Solubility Behaviour of TiCl 4 , ZrCl 4 , and HfCl 4 in Chloroaluminate Ionic Liquids

The solubility of NbCl 5 , TaCl 5 , TiCl 4 , ZrCl 4 , and HfCl 4 in neutral [BMIM][AlCl 4 ] (BMIM = 1‐butyl‐3‐methylimidazolium) was determined. While TiCl 4 was immiscible with the neutral ionic liquid, 0.80 molar equivalents of ZrCl 4 and stoichiometric amounts of HfCl 4 dissolved in the melt at ambient temperature. The crystal structures and the unit cell parameters of [BMIM] 2 [Ti 2 Cl 10 ], [BMIM] 2 [Zr 2 Cl 10 ], and [PhNMe 3 ][Hf 2 Cl 9 ] were determined. [BMIM] 2 [Ti 2 Cl 10 ], and [BMIM] 2 [Zr 2 Cl 10 ] were crystallised from basic chloroaluminate melts. With a trimethylanilinium cation, [PhNMe 3 ][Hf 2 Cl 9 ] crystallised from an equimolar composition of PhNMe 3 Cl, AlCl 3 , and HfCl 4 . Obviously, HfCl 4 abstracted a chloride ligand from [AlCl 4 ] – to give highly Lewis acidic [Al 2 Cl 7 ] – anions.