Figure 4.

Distance dependence of Arrhenius prefactors for electron-transfer reactions between a Au electrode and redox couples attached to the termini of oligomethylene (directly linked Fc, ●; ester-linked Fc, ○; Ru(pyridine)(NH₃)₅²⁺, ▽) and oligovinylene (×) spacers. For distances >12 Å (1.2 nm), oligomethylene rates are described by an exponential distance decay of 10.6 nm^–1 (solid line). The dotted line shows the prefactor expected for reactions limited by solvent dynamics. Reprinted with permission from ref (51). Copyright 2003 American Chemical Society.