Evidence for hydrogen bonds in 1,2-dimethyl-3-propylimidazolium chloride and its chloroaluminate molten salts

The crystal structure of l,2-dimethyl-3-propylimidazoIium chloride (DMPICl) reveals the formation of hydrogen bonds between the ring, methyl, and methylene hydrogens and the chloride ion. Although the aromatic rings are found in stacks, aromatic-aromatic interactions are precluded by the 6.98 Å distance between the rings. From IR and¹HNMR spectroscopies, it is determined that only the hydrogen bonds between the ring hydrogens and the chloride ion persist in the room-temperature molten salts obtained from combining DMPIC1 with AlCl₃.