Unprecedented iminobenzosemiquinone and iminobenzoquinone coordinated mononuclear Cu(ii) complex formation under air.

Two non-innocent 2-anilino-4,6-di-tert-butylphenol units were connected through an -ortho bridging S atom and provided the ligand . The ligand reacted with CuCl2·2H2O in the presence of Et3N under air and generated a mononuclear Cu(ii) complex (1, [CuL(S(IBQ/ISQ))Cl](0)). A single crystal X-ray diffraction analysis confirmed that in the complex one of the two 2-anilido-4,6-di-tert-butylphenol arms was present in its one-electron oxidized iminobenzosemiquinone form, while the other was in its two-electron oxidized iminobenzoquinone form. The monoradical-containing Cu(ii) complex was diamagnetic in nature owing to a strong antiferromagnetic coupling between the single electron containing dx(2)-y(2) magnetic orbital of Cu(ii) and the radical-centered unpaired electron.