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.