PNNL

Abstract

Ferrocene (Fc) and N-(ferrocenylmethyl)-N,N-dimethyl-N-ethylammonium bistrifluoromethyl-sulfonimide (Fc1N112-TFSI) were dissolved in carbonate solvents and self diffusion coefficents (D) of solutes and solvents were measured by 1H and 19F pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy. The organic solvents were propylene carbonate (PC), ethyl methyl carbonate (EMC) and a ternary mixture that also includes ethylene carbonate (EC). Results from NMR studies over the temperature range of 0-50 °C and for various concentrations (0.25 - 1.7 M) of Fc1N112-TFSI are compared to values of D simulated with classical molecular dynamics (MD). The measured self-diffusion coefficients gradually decreased as the Fc1N112-TFSI concentration increased in all solvents. Since the peaks for the two ions (Fc1N212 and TFSI) are separated in one-dimensional NMR spectra, separate diffusion coefficients could be measured and DTFSI is larger than DFc1N112 in all samples measured. The EC, PC and EMC have the same D in the neat solvent mixture and when Fc is dissolved in EC/PC/EMC at a concentration of 0.2 M, probably due to the interactions between common carbonyl structures within EC, PC and EMC. A difference in D (DPC