Experimental Validation of Marcus Theory for Outer‐Sphere Heterogeneous Electron‐Transfer Reactions: The Oxidation of Substituted 1,4‐Phenylenediamines

Rate constants depend on molecular size: Results are presented to validate the relationship between molecular size and the standard electrochemical rate constant predicted by Marcus theory (see graphic). Measurement of hydrodynamic radii and electron-transfer rates for substituted 1,4-phenylenediamines have been made under steady-state conditions using both hydrodynamic and stationary electrodes.