The electrolytic reduction of [OsCl6]2- in the basic aluminum chloride-1-methyl-3-ethylimidazolium chloride (AlCl3-MeEtimCl) room temperature ionic liquid produces [OsCl6]3-. The [OsCl6]2- + e- ⇌[OsCl6]3- electrode reaction exhibits reversible behavior at a glassy carbon electrode in this solvent and appears reversible at this electrode in pure molten MeEtimCl at 103°C as well. The formal electrode potential for this redox system in the 49.0/51.0 mole percent (m/o) AlCl3-MeEtimCl melt is approximately -0.31V vs. Al in the 66.7/33.3 m/o ionic liquid. The average Stokes-Einstein products for the [OsCl6]2- and [OsCl6]3- ions are 6.6 x 10-8 and 4.7 x 10–8 g cm s-2, respectively, at 40°C and are slightly larger than those previously found for the corresponding iridium complexes. Absorption spectra for [OsCl6]2- and [OsCl6]3- in basic AlCl3-MeEtimCl are similar to the spectra of these complexes in aqueous HC1 solution, but seem to be less distorted. Molar absorptivities for the [OsCl6]3- ion are reported for the first time.
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