Structural features and electronic properties of a cupric complex with redox active 1-(2-pyridylazo)-2-phenanthrol (papl)

We report the structural properties and electronic structure of a neutral homoleptic copper(II) complex bearing the anion of 1-(2-pyridylazo)-2-phenanthrol (papl). In the solid state the complex is disordered and this presents itself as a nearly equal mixture of five and six coordinate copper ions with the ligand bound in two different configurations, with one of the terminal pyridine rings uncoordinated in the case of the five coordinate ion, which also features a very short Cu-N_azo coordinate bond. The six coordinate complex features a Jahn-Teller elongated octahedron with one of the ligands coordinated in a typical fashion with coordinate bond distances typical of other divalent ion-papl complexes while the distances to the other donor atoms are much longer.