Ligand effects on the chemical activity of copper(I) complexes: Outer- and inner-sphere oxidation of Cu^IL

The effect of the ligands acetonitrile (AN), fumaric acid (H ₂fum) and 2,5,8,11-tetramethyl-2,5,8,11-tetraazadodecane (L ¹) on the kinetics of oxidation of Cu^I complexes by [(cy-clam)Ni^III(SO₄)₂] and [(NH ₃)₅Co^IIIC1]²⁺ in aqueous solutions via an outer- and inner-sphere mechanism, respectively, has been studied. The effects of the ligands on the electron self-exchange rate constants have also been evaluated. All ligands studied stabilize Cu^I in aqueous solution but affect the redox potential of the Cu^II/IL couple differently. The ligands decrease the rate of the redox reactions and the electron self-exchange rate constants. The results indicate that acetonitrile and alkenes should not be used as solvents for [Cu^IL]⁺-catalyzed processes that involve redox steps. On the other hand, the results also suggest that [Cu^IL¹]⁺ should be a good catalyst for such processes.