The monomeric rhenium(IV) chloride complex [ReCl6]2−is stable in the basic aluminum chloride-1-methyl-3-ethylimidazolium chloride molten salt, and it can be reduced voltammetrically to [ReCl6]3−at a glassy-carbon electrode in a reversible process with a half-wave potential of −0.87 V in the 49.0/51.0 mol % melt versus the A13+/A1 couple in the 66.7/33.3 mol % melt. The Stokes-Einstein product for this complex is 2.3 × 10−10g cm s−2K−1. The dimeric, metal-metal-bonded rhenium(IV) complex [Re2Cl9]−can be reduced voltammetrically to [Re2Cl9]2−in a reversible electrode reaction with a half-wave potential of approximately 0.56 V in the 49.0/51.0 mol % melt. However, [Re2Cl9]−exhibits only limited stability in the melt and slowly converts to [ReCl6]2−. The dimeric rhenium(IV,III) complex [Re2Cl9]2−can be reduced electrochemically to the dimeric rhenium(III) species [Re2Cl8]2−in an irreversible process. The Stokes-Einstein product for this complex is 1.6 × 10−10g cm s−2K−1. Like [Re2Cl9]−, [Re2Cl9]2−exhibits only limited stability in the melt; it slowly converts to a mixture of [ReCl6]2−and [Re2Clg]2−. The conversion process is second order in [Re2Cl9]2−with a rate constant of 7.34 × 10−3M−1s−1at 31 °C and an activation energy of approximately 92 kJ mol−1.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry
- Inorganic Chemistry