Figure 64.

(A) Strategy of Masuda and co-workers for systematic introduction of H-bonding groups of varying strengths into the TMPA ligand framework.^{700,701,722,723} (B) Crystal structure (50% probability) of the stable (L^Piv2)Cu^II-OOH species showing two H-bonds to the proximal O atom.⁷⁰¹ (C) Spectroscopically characterized [(BA)Cu^II–OOH]⁺ species stable at low temperature.⁷²⁰ (D and E) Ligands with and without substituents positioned to H-bond to the distal O atom of a Cu^II-OOH species.⁷⁰⁰ (F) Overall conclusions regarding the stability or reactivity imposed by H-bonding to proximal vs distal O atoms for LCu^II-OOH complexes.⁷²¹