# Revised and Extended Values for Self-Diffusion Coefficients of 1‑Alkyl-3-methylimidazolium Tetrafluoroborates and Hexafluorophosphates: Relations between the Transport Properties

journal contribution

posted on 30.11.2016, 00:00 by Kenneth R. Harris, Mitsuhiro KanakuboEarlier
measurements of the self-diffusion coefficients of 1-alkyl-3-methylimidazolium
(or [RMIM], R = alkyl) tetrafluoroborates and hexafluorophosphates
have been revised and extended to 90 °C. The main changes are
to

*D*_{S+}and*D*_{S–}for [HMIM][PF_{6}] ([C_{6}C_{1}Im][PF_{6}]) and*D*_{S–}for [OMIM][BF_{4}] ([C_{8}C_{1}Im][BF_{4}]). New atmospheric pressure self-diffusion, density, and conductivity data are provided for [HMIM][BF_{4}] ([C_{6}C_{1}Im][BF_{4}]). Velocity cross-correlation, distinct diffusion, and Laity resistance coefficients have been calculated. There is no evidence for ion association. A new relation between the Nernst–Einstein deviation parameter (Δ) and resistance coefficients (*r*_{ij}) is derived; Δ tends toward 0.5 when the like-ion*r*_{ii}are much smaller than the unlike-ion*r*_{ij}, i.e., when the counterion interactions dominate. [OMIM]^{+}ion salts approach this limit. Stokes–Einstein–Sutherland and Walden plots overlap almost quantitatively for [BF_{4}]^{−}, [PF_{6}]^{−}, and Cl^{–}salts with a common [RMIM]^{+}cation. That is, in thermodynamic states that have the same viscosity, the salt molar conductivities and hence ionic electrical mobilities of, say, [BMIM][BF_{4}] and [BMIM][PF_{6}] are almost equal, as are the corresponding Brownian or diffusive mobilities, (*D*_{Si}/*RT*), for the cation, and also for these three small anions.## Read the peer-reviewed publication

## Categories

## Keywords

self-diffusion coefficientsresistance coefficientsRTOMIMcounterion interactionsLaity resistance coefficientsBF 4r ijdiffusive mobilitiesD Sconductivity dataunlike-ion r ijExtended Valueslike-ion r iiion associationPF 6cationSelf-Diffusion Coefficientsion salts approach1- alkyl -3-methylimidazoliumTransport PropertiesWalden plots overlapBMIMsalt molar conductivitiespressure self-diffusionRMIMHMIMIm

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## Read the peer-reviewed publication

## Categories

## Keywords

self-diffusion coefficientsresistance coefficientsRTOMIMcounterion interactionsLaity resistance coefficientsBF 4r ijdiffusive mobilitiesD Sconductivity dataunlike-ion r ijExtended Valueslike-ion r iiion associationPF 6cationSelf-Diffusion Coefficientsion salts approach1- alkyl -3-methylimidazoliumTransport PropertiesWalden plots overlapBMIMsalt molar conductivitiespressure self-diffusionRMIMHMIMIm