In all cases TLC test of the final product was performed on a silica plate, to check for side products and contaminations. The eluent used was a 4:1:1 mixture of acetonitrile, methanol and water, saturated with KNO 3 . The 1 H NMR measurements have shown that the products contain significant amount of crystalline solvents. ICP-MS measurements were carried out to determine the exact Fe content of the complexes, to allow for accurate determination of the molar extinction coefficients.