Reactivity of a 1:1 copper-oxygen complex:: isolation of a Cu(II)-o-iminosemiquinonato species

While a 1:1 Cu-O-2 adduct is generally unreactive with organic substrates, phosphines displace O-2 via an associative process and added Cu(I) leads to a novel internal ligand oxidation to yield a Cu(II)-o-iminosemiquinone complex.