Free-energy barrier of gated electron transfer reactions: reduction and oxidation reactions of Cu(6,6′-dimethyl-2,2′-bipyridine)22+/+ with Ru(hexafluoroacetylacetone)30/−

Redox reactions of Cu(dmbp)22+/+ (dmbp=6,6′-dimethyl-2,2′-bipyridine) were examined in acetonitrile. It was found that the reaction of Cu(dmbp)22+ was gated, involving a slow structural change in Cu(II) prior to the electron transfer process. The energetic origin of the gated phenomenon was discussed by comparing the activation barriers for the intermolecular gated, intramolecular directional and outer-sphere concerted (direct) pathways.