Molecular Structure of the Bis[tris(2-aminoethyl)aminecyano]dicobalt(III) Ion and its UV/VIS Spectrum

Formation of μ-peroxodicobalt(III) complexes has been studied in solutions containing tris(2-aminoethyl)aminecobalt(II) and additional monodentate ligands X. Depending n the nature and the concentration of X and on pH, singly bridged (tren)XCoOOCoX(tren)]⁴⁺ and/or doubly bridged (tren)Co(C₂OH)Co(tren)]³⁺ are formed. The UV/VIS spectra of these complexes are discussed on the basis of a theoretical model which stresses the importance of the dihedral angle of the CoOOCo-group. (tren)(CN)CoOOCo(CN)(tren)](ClO₄)₂ has been synthesized and its structure determined by single crystal X-ray diffraction. The CoOOCo-group of the cation is planar. Solutions of the complex as well as the solid show two CT bands in the 300–400 nm region.