Figure 4.

(a) UV–vis spectra of [Cu^II(ε-HGH)(OOH)]⁺ generated by addition of 1.5 equiv of H₂O₂ to a 3.5 mM solution of 2 in acetone at 193 K. (b) EPR spectrum of [Cu^II(ε-HGH)(OOH)]⁺ at 77 K (g_∥ = 2.25, g_⊥ = 2.05, A_∥ = 192 G, A_⊥ = 15 G).