XPS detection of unusual Cu(II) to Cu(I) transition on the surface of complexes with redox-active ligands

Electronic structure of copper complexes with redox-active ligands was studied by XPS. The temperature dependence of the redistribution of electron and spin densities was shown. A low temperature anomaly of magnetic properties of the copper complex with redox-active ligands was detected. The observed two states of copper (Cu+1 and Cu+2) allowed proposing valence tautomerism («redox-isomer» copper complex). The donating role of nitrogen atoms was established in the copper complex with redox-active ligand. The role of ligands in the formation of the electronic structure of square-planar complexes was revealed. © 2019 Elsevier B.V.