C-13 NMR RELAXATION AND H-1 DIFFUSION (DOSY) STUDIES OF AN ACIDIC CHLOROALUMINATE MELT

C-13 NMR relaxation studies of a 2:1 AlCl3:1-ethyl-3-methylimidazolium chloride (MEICl) melt between 26 and 57 degrees C provide rotational correlation times for MEI(+) which are compared with viscosities and d iffusion coefficients. Diffusion coefficients for MEICl in a 2:1 AlCl3 -MEICl melt are determined using H-1 diffusion ordered spectroscopy (D OSY) between 26 and 57 degrees C. All MEI(+) diffusion coefficients (r ing, methyl, and ethyl protons) are virtually identical at a given tem perature. The MEI(+) diffusion coefficients are viscosity dependent an d correlate with conductivity and C-13 NMR rotational correlation time s, indicating that the transport properties of the 2:1 AlCl3-MEICl mel t are determined by the molar quantities of salt and not by the proper ties of the individual ions. Microviscosity factors provide reasonable values for the radius of MEI(+) from both viscosity and C-13 NMR rota tional correlation times. The ''slip'' model is used to describe the m ovement of MEI(+) in the 2:1 AlCl3-MEICl melt where Al2Cl7- is the pre dominant anion. The ab initio structures of AlCl4- and Al2Cl7- have be en calculated at the HF/6-31G(d) level.