ELECTRON AND MASS-TRANSPORT IN HYBRID REDOX POLYETHER MELTS - CO AND FE BIPYRIDINES WITH ATTACHED POLYETHER CHAINS

The coupling of electron self exchange reactions with physical diffusi on has been used to measure electron transfer rate constants in a seri es of undiluted metal complex molten salts [M(bpy(CO(2)MePEG)(2))(3)]( ClO4)(2) where M = Co(II/I) and Fe(III/II) and MePEG is an, oligomeric polyether of MW 150, 350, and 550. Physical self-diffusion rates in t he melts vary with attached polyether chain length by over 10(3)-fold while the electron transfer rate constants show no strong systematic d ependence. The electron transfer rates and activation parameters indic ate that the metal complex cores move rapidly within their attached po lyether ''solvent'' shells relative to the rates of electron transfers , which are near adiabatic with large activation barriers reflecting t he apparent inability of the attached polyether chains to act as a fre ely mobile ''solvent''. Ionic conductivities of the melts were measure d in order to inspect for ionic and electronic migration effects which are present to minor degrees. Diffusion and heterogeneous transfer ra tes are also reported for dilute solutions of the cobalt complexes in a polyether solvent.