Figure 4.

(a) Structure of [{(TMPA)Cu^II}₂(μ-1,2-O₂^2–)]²⁺ obtained from X-ray crystallography and (b) low-temperature UV–vis absorption spectra of [{(TMPA)Cu^II}₂(μ-1,2-O₂^2–)]²⁺ (purple) and [{(ESE)-Cu^II}₂(μ-1,2-O₂^2–)]²⁺ (blue).^9b,25