ChemInform Abstract: Dioxygen-Copper Reactivity. Comparisons of the Reactions of Electrophiles and Other Reagents with Three Classes of Peroxo-Dicopper(II), (Cu2-O2)n+, Species.

ChemInform Abstract

The results indicate that in (I) and (VII) the peroxo ligand can act as a base or nucleophile, whereas the behavior of (IV) is consistent with an electrophilic nature. The reaction of SO₂ with these complexes gives sulfato-containing products (III) (a corresponding complex is obtained from (VII)) or (VI). The reaction of (VII) and (I) with CO₂ gives solutions of peroxycarbonato species which, via thermal decomposition or by reaction with PPh₃ (producing POPh₃), affords carbonato-bridged complexes such as (IX) (space group P1, Z=2). (IV) does not react. The peroxo ligands in (I) and (VII) are readily protonated with 1 equiv. HBF₄ or HBF₆ at -80 °C to give a hydroperoxo-dicopper(II) complex; with 2 or more equiv. of H⁺, H₂O₂ is produced in more than 80% yield. (IV) cannot be protonated or acylated. The acylation of (I) or (VII) proceeds similarly leading to (XI) in the case of (I) via conversion of the corresponding μ-benzoylperoxo complex with PPh₃. Reaction of PPh₃ with (I) or (VII) at -80 °C displaces O₂ to give PPh₃-coordinated Cu(I) products. A similar reaction does not occur with (IV). The differences in reactivity between the title complexes may be attributed to the presence of fewer ligand donors per Cu in (IV) compared to the others or it may be considered the existence of an unusual η2,η2-O2 structural moiety.