Metal-Ligand Electronic Interactions in Mononuclear and Dinuclear Triethylenetetraminecobalt(III) Complexes Containing the Anion of Quinizarin (1,4-Dihydroxy-9,10-anthraquinone)

1,4-Dihydroxy-9,10-anthraquinonatotriethylenetetraminecobalt(III) cation and its conjugate acid and the tetrapositive dinuclear μ-1,4-dihydroxy-9,10-anthraquinonatotriethylenetetraminecobalt(III) cation have been prepared in aqueous solution and characterized by spectroscopy and cyclical voltammetry. Both spectra and electrochemistry indicate that there is significant interaction between ligand-centered orbitals and metal-centered orbitals in all three species.