Complexing of some rare-earth metal chlorides with aluminum chloride and use of these complexes for the polymerization of dienes

The anhydrous neodymium, praseodymium, and yttrium chlorides react with AlCl5 to give LnCl3·4AlCl3 complexes that are soluble in aromatic hydrocarbons. The lanthanide concentration in solution increases by one order of magnitude if an organoaluminum compound is added to the reaction mixture after the completion of complex formation between the lanthanide and aluminum chlorides.