Oxidation of (5,7,7,12,14,14-hexamethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene)copper(II) by radicals produced by flash photolysis and reactions of the oxidized copper complex

Abstract

The title complex, [CuL¹]²⁺, is oxidized in aqueous solution by OH and [Cl₂]^– radicals generated by flash photolysis. The oxidation by OH radicals is initiated by H-atom abstraction from the ligand (k 1.5 × l0¹⁰ dm³ mol^–1 s^–1). The spectrum of the transient oxidized copper complex is more characteristic of a copper(II)–ligand-radical species than of a copper(III) macrocyclic complex. The oxidized complex is itself a powerful oxidant, oxidizing Cl^– to Cl₂(k 1.5 × 10³ dm³ mol^–1 s^–1), [N₃]^– to N₂(k 2.5 × 10⁴ dm³ mol^–1 s^–1), and H₂O₂ to HO₂(k 7.0 × 10² dm³ mol^–1 s^–1) as well as HO₂ and [O₂]^– radicals. The oxidized [CuL¹]²⁺ species is probably an intermediate in the decay of [CuL¹]³⁺ in acetonitrile.