Electrochemistry in Near-Critical and Supercritical Fluids. 8. Methyl Viologen, Decamethylferrocene, Os(bpy)3(2+) and Ferrocene in Acetonitrile and the Effect of Pressure on Diffusion Coefficients under Supercritical Conditions.

摘要

The cyclic voltammetry (CV) of methyl viologen (MV(2+)), decamethylferrocence (DMFc), Os(bpy)3(2+) (bpy+2,2'-bipyridine) and ferrocene (Fc) was studied at high temperatures and pressures in a small cell (7.5 ml) where the pressure and temperature could be varied independently. While the CV of MV(2+) and OS(bpy)3(3+) remained well-behaved with reversible of quasi-reversible waves only into the near-critical region (up to ca 230 C), Fc and DMFc showed well-defined behavior under supercritical conditions. The diffusion coefficient of ferrocene was measured at a supercritical temperatures (280 C) as a function of pressure, and the experimental results were correlated to values calculated by the Stokes-Einstein relation. (AW)