Redox couple

Ligand/Nucleophile

Cu⁺/Cu⁰

Ag⁺/Ag⁰

Au⁺³/Au⁰

H₂O

+0.521

+0.799

+1.500

Cl⁻

+0.137

+0.222

+1.000

Br⁻

+0.033

+0.090

+0.870

SCN⁻

−0.270

-

+0.660

I⁻

−0.185

−0.150

+0.500

CN⁻

−0.430

−0.310

−0.600