Journal of Physical Chemistry B, Vol.102, No.10, 1717-1723, 1998
C-13 and Al-27 NMR relaxation, viscosity, and H-1 diffusion studies of an ethylaluminum dichloride melt
C-13 and Al-27 NMR relaxation studies of a 1:1 1-ethyl-3-methylimidazolium chloride (MEICI)-ethylaluminum dichloride (EtAlCl2) melt provide rotational correlation times for MEI+ and EtAlCl2 which are compared with viscosities and diffusion coefficients. Diffusion coefficients for MEICl and EtAlCl2 in a 1:1 MEICl-EtAlCl2 melt are determined simultaneously using H-1 diffusion ordered spectroscopy (DOSY). All MEI+ diffusion coefficients (ring, methyl, and ethyl protons) are virtually identical at a given temperature as are the methylene and methyl protons of EtAlCl2. The MEI+ and EtAlCl2 diffusion coefficients are viscosity dependent and correlate with C-13 and Al-27 NMR rotational correlation times, indicating that the transport properties of the 1:1 MEICl-EtAlCl2 melt are determined by the molar quantities of salt and not by the properties of the individual ions. Microviscosity factors provide reasonable values for the radius of MEI+ from both viscosity and C-13 NMR rotational correlation times. The "slip" model is used to describe the movement of MEI+ in the 1:1 MEICl-EtAlCl2 melt.
Keywords:CHLORIDE-ALCL3 MOLTEN-SALTS;ORDERED 2D NMR;IONIC STRUCTURE;1-METHYL-3-ETHYLIMIDAZOLIUM CHLORIDE;CHLOROALUMINATE MELTS;MOLECULAR-SIZE;SPIN PROBE;SPECTROSCOPY;CONDUCTIVITIES;COEFFICIENTS